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  • 101.
    Johnson, Lars
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Thuvander, Mattias
    Chalmers University of Technology.
    Stiller, Krystyna
    Chalmers University of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Spinodal decomposition of Ti0.33Al0.67N thin films studied by atom probe tomography2012In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 520, no 13, p. 4362-4368Article in journal (Refereed)
    Abstract [en]

    Details of the phase decomposition in NaCl-structure Ti0.33Al0.67N thin films deposited by cathodic arc evaporation are studied by atom probe tomography. We demonstrate that as-deposited films are in the earliest stage of decomposition for which electron microscopy and x-ray diffraction indicate a single-phase solid solution. Annealing at 900 degrees C further activates spinodal decomposition of the films, although pockets of unde-composed material remain after 2 h. N preferentially segregates to the AlN and TiN domains, causing the TiAlN matrix to be understoichiometric, by the energetics of N vacancies in TiAlN. The corresponding modulation in stoichiometry implies a Kirkendall effect, caused by different Al and Ti diffusivities.

  • 102.
    Rogström, Lina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Ullbrand, Jennifer
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Almer, J.
    Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 USA.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jansson, B.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology. Seco Tools AB, 737 82 Fagersta, Sweden.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Strain evolution during spinodal decomposition of TiAlN thin films2012In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 520, no 17, p. 5542-5549Article in journal (Refereed)
    Abstract [en]

    We use a combination of in-situ x-ray scattering experiments during annealing and phase-field simulations to study the strain and microstructure evolution during decomposition of TiAlN thin films. The evolved microstructure is observed to depend on composition, where the larger elastic anisotropy of higher Al content films causes formation of elongated AlN and TiN domains. The simulations show strain formation in the evolving cubic-AlN and TiN domains, which is a combined effect of increasing lattice mismatch and elastic incompatibility between the domains. The experimental results show an increased compressive strain in the TiAlN phase during decomposition due to the onset of transformation to hexagonal-AlN.

  • 103.
    Escalera, Edwin
    et al.
    Division of Engineering Materials, Department of Applied Physics and Mechanical Engineering, Luleå University of Technology, Luleå, Sweden..
    Ballem, Mohamed A.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Cordoba, José M.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Antti, Marta-Lena
    Division of Engineering Materials, Department of Applied Physics and Mechanical Engineering, Luleå University of Technology, Luleå, Sweden.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Synthesis of homogeneously dispersed cobalt nanoparticles in the pores of functionalized SBA-15 silica2012In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 221, no S1, p. 359-364Article in journal (Refereed)
    Abstract [en]

    Cobalt nanoparticles were prepared at room temperature by reducing cobalt sulfate heptahydrate with sodium borohydride and using functionalized SBA-15 mesoporous silica as a hard template. It was found that both external and internal fuctionalization of silica walls play a crucial role on the infiltration and reaction of the reagents in the silica framework. Subsequent heat treatment of the impregnated silica at 500 °C in air or nitrogen atmospheres leads to growth of crystals of the deposited cobalt and formation of cobalt and cobalt oxide nanoparticles, respectively. Dissolution of the silica template by NaOH resulted in well dispersed Co and Co3O4 nanoparticles ranging in size from 2 to 4 nm. The functionalization of the silica was studied by FTIR, N2-physisorption, and thermogravimetric techniques and the obtained nanoparticles were characterized by XRD, TEM and EDX analysis.

  • 104.
    Escalera, Edwin
    et al.
    Division of Materials Science, Luleå University of Technology.
    Antti, M.
    Division of Materials Science, Luleå University of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Thermal treatment and phase formation in kaolinite and illite based clays from tropical regions of Bolivia2012Conference paper (Refereed)
    Abstract [en]

    The aim of this study was to compare the thermal behaviour of clays containing illite and kaolinite in various proportions. The clays contained small amounts of K and Fe, which act as fluxing agents. In order to investigate the phase formations during heating, the samples were examined in a differential scanning calorimeter at temperatures up to 1300°C. The thermal expansion of the samples was determined by dilatometer measurements from room temperature up to 1150°C. Phases were identified using x-ray diffraction and scanning electron microscopy.

    In all samples, most of the kaolinite was transformed into metakaolinite during heating up to 650°C, while illite remained unchanged up to 950°C. There was no influence of K and Fe on dehydroxylation. Metakaolinite formed at temperatures above 950°C leading to a Si-Al spinel. Furthermore, mullite was formed in the temperature interval 1050-1150°C. In this temperature range, the mechanism of mullite formation depended on the amount of K and Fe in the samples, changing the temperature of formation of mullite. It was observed by x-ray diffraction that most of the illite was transformed into a Si-Al spinel phase at 1050°C, and during further heating transformed into mullite. An increased amount of illite in the clays slightly decreased the melting temperature. The dilatometer measurements showed expansion and shrinkage for the dehydroxylation and spinel-phase formation, respectively.

  • 105.
    Frodelius, Jenny
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Johansson, Emma M.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Córdoba, José M.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Annealing of thermally sprayed Ti2AlC coatings2011In: INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, ISSN 1546-542X, Vol. 8, no 1, p. 74-84Article in journal (Refereed)
    Abstract [en]

    Phase transformations during annealing of coatings sprayed with the High Velocity Oxy-Fuel technique using Ti2AlC powder have been investigated by in-situ x-ray diffraction. The asdeposited coatings, consisting of Ti2AlC, Ti3AlC2, TiC, Ti-Al, and oxides, are stable up to 500 °C. Ti3AlC2 forms above 550 °C and Ti2AlC forms above 700 °C by intercalation of Al into TiCx. For temperatures between 900 and 1100 °C, Ti3AlC2 and Ti2AlC decompose by losing Al to the surrounding matrix resulting in TiCx, and Al2O3. The thermal expansion coefficient between ambient and 700°C is 11.9·10-6 K-1. The thermal diffusivity at room temperature is 1.9·10-6 m2/s.

  • 106.
    Cordoba Gallego, Jose Manuel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Ballem, Mohamed
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Johansson, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Growth of single crystalline dendritic Li(2)SiO(3) arrays from LiNO(3) and mesoporous SiO(2)2011In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 184, no 7, p. 1735-1739Article in journal (Refereed)
    Abstract [en]

    A solution based wet chemistry approach has been developed for synthesizing Li(2)SiO(3) using LiNO(3) and mesoporous silica as starting materials at 550 degrees C. A reaction path where NO and O(2) are formed as side-products is proposed. The crystals synthesized exhibit dendritic growth where the as-prepared nanodendrite is a typical 1-fold nanodendrite composed of one several microns long and some tenth of nanometers wide trunk with small branches, which are several hundreds of nanometers long and up to 70 nm in diameter. The effect of the structure of the mesoporous silica for the final morphology is discussed.

  • 107.
    Lind, Hans
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Forsén, Rikard
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Ghafoor, Naureen
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Tasnadi, Ferenc
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Johansson, M P
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Improving thermal stability of hard coating films via a concept of multicomponent alloying2011In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 99, no 9, p. 091903-Article in journal (Refereed)
    Abstract [en]

    We propose a design route for the next generation of nitride alloys via a concept of multicomponent alloying based on self-organization on the nanoscale via a formation of metastable intermediate products during the spinodal decomposition. We predict theoretically and demonstrate experimentally that quasi-ternary (TiCrAl)N alloys decompose spinodally into (TiCr)N and (CrAl)N-rich nanometer sized regions. The spinodal decomposition results in age hardening, while the presence of Cr within the AlN phase delays the formation of a detrimental wurtzite phase leading to a substantial improvement of thermal stability compared to the quasi-binary (TiAl)N or (CrAl)N alloys.

  • 108.
    Eriksson, Anders
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Zhu, Jianqiang
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Ghafoor, Naureen
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Johansson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology. Seco Tools AB, Sweden.
    Sjölen, Jacob
    Seco Tools AB, Sweden.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Layer Formation by Resputtering in Ti-Si-C Hard Coatings during Large Scale Cathodic Arc Deposition2011In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 205, no 15, p. 3923-3930Article in journal (Refereed)
    Abstract [en]

    This paper presents the physical mechanism behind the phenomenon of self-layering in thin films made by industrial scale cathodic arc deposition systems using compound cathodes and rotating substrate fixture. For Ti-Si-C films, electron microscopy and energy dispersive x-ray spectrometry reveals a trapezoid modulation in Si content in the substrate normal direction, with a period of 4 to 23 nm dependent on cathode configuration. This is caused by preferential resputtering of Si by the energetic deposition flux incident at high incidence angles when the substrates are facing away from the cathodes. The Ti-rich sub-layers exhibit TiC grains with size up to 5 nm, while layers with high Si-content are less crystalline. The nanoindentation hardness of the films increases with decreasing layer thickness.

  • 109.
    Knutsson, Axel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Johansson, M P
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Karlsson, L
    Seco Tools AB.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Machining performance and decomposition of TiAlN/TiN multilayer coated metal cutting inserts2011In: SURFACE and COATINGS TECHNOLOGY, ISSN 0257-8972, Vol. 205, no 16, p. 4005-4010Article in journal (Refereed)
    Abstract [en]

    The wear resistance of metal cutting inserts coated with metastable Ti0.34Al0.66N/TiN multilayers was tested in continuous turning of an AISI 316L stainless steel. The multilayers had periods of 25 + 50, 12 + 25 and 6 + 12 nm (Ti0.34Al0.66N + TiN) with a total multilayer stack thickness of 2 mu m. Inserts coated with monolithic TiN and Ti0.34Al0.66N deposited under similar conditions were used as references. The multilayer coated inserts show a decrease of wear with decreased multilayer period, both on the rake and flank face. The wear on the rake face was lower on all the multilayer coated tools compared to the references. Scanning transmission electron imaging and energy dispersive spectroscopy elemental mapping of a worn multilayer coating show decomposition of the Ti0.34Al0.66N to domains rich of Al and Ti. High resolution transmission electron micrography shows preserved epitaxy between the TiN and Ti0.34Al0.66N layers. The improved wear resistance of the multilayer coated inserts is discussed in terms of an improved thermal stability of the multilayer stacks.

  • 110.
    Ballem, Mohamed A.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Córdoba, José
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Mesoporous silica templated zirconia nanoparticles2011In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 13, no 7, p. 2743-2748Article in journal (Refereed)
    Abstract [en]

    Nanoparticles of zirconium oxide (ZrO2)were synthesized by infiltration of a zirconia precursor(ZrOCl28H2O) into a SBA-15 mesoporous silicamold using a wet-impregnation technique. X-raydiffractometry and high-resolution transmission electronmicroscopy show formation of stable ZrO2nanoparticles inside the silica pores after a thermaltreatment at 550 C. Subsequent leaching out of thesilica template by NaOH resulted in well-dispersedZrO2 nanoparticles with an average diameter of*4 nm. The formed single crystal nanoparticles arefaceted with 110 surfaces termination suggesting it tobe the preferred growth orientation. A growth modelof these nanoparticles is also suggested.

  • 111.
    Knutsson, Axel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Ullbrand, Jennifer
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Rogström, Lina
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Almer, J.
    Advanced Photon Source, Argonne National Laboratory, Argonne, IL, 60439 USA.
    Jansson, B.
    Seco Tools AB, 737 82 Fagersta, Sweden.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Microstructure evolution during annealing of TiAlN-coatings: A combined in-situ SAXS and phase field study2011Manuscript (preprint) (Other academic)
    Abstract [en]

    This paper describes in detail the microstructure evolution of Ti0.33Al0.67N and Ti0.50Al0.50N coatings during isothermal annealing studied by in-situ small angle x-ray scattering (SAXS) in combination with phase field simulations. We show that the decomposition occurs in two stages consistent with spinodal decomposition. During the initial stage, the phase segregation proceeds with a constant size of AlN- and TiN-rich domains with a radius of ~0.7 nm for 5 and 20 min at 900 and 850 C respectively in the Ti0.50Al0.50N alloy. The length of the initial stage depends on the temperature as well as the composition, and is shorter for the higher Al content coating. Following the initial stage, the AlN- and TiN-rich domains coarsen. The decomposition process is discussed in terms of Gibbs free energy, diffusion, and gradient energies. Scanning transmission electron microscopy and energy dispersive x-ray spectroscopy of the post annealed coatings confirm a decomposed microstructure with coherent domains rich in AlN and TiN of the same size as determined by SAXS.

  • 112.
    Zhu, Jianqiang
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Eriksson, Anders O.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Ghafoor, Naureen
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Microstructure evolution of Ti3SiC2 compound cathodes during reactive cathodic arc evaporation2011In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 29, no 3, p. 031601-Article in journal (Refereed)
    Abstract [en]

    The microstructure evolution and compositional variation of Ti3SiC2 cathode surfaces during reactive cathodic arc evaporation are presented for different process conditions. The results show that phase decomposition takes place in the near-surface region, resulting in a 5-50 mu m thick converted layer that is affected by the presence of nitrogen in the deposition chamber. This layer consists of two different sublayers, i.e., 1-20 mu m thick top layer with a melted and resolidified microstructure, followed by a 4-30 mu m thick transition layer with a decomposed microstructure. The converted layer contains a polycrystalline TiCx phase and trace quantities of Si-rich domains with Ti5Si3(C) at their interface. The arc discharge causes Si redistribution in the two regions of the layer, whose Si/(Ti+Si) ratio is higher in the top region and lower in the transition region compared to the virgin material.

  • 113.
    Spencer, C B
    et al.
    Drexel University.
    Cordoba Gallego, Jose Manuel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Obando, N
    Texas A&M University.
    Sakulich, A
    Drexel University.
    Radovic, M
    Texas A&M University.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Barsoum, M W
    Drexel University.
    Phase Evaluation in Al(2)O(3) Fiber-Reinforced Ti(2)AlC During Sintering in the 1300 degrees C-1500 degrees C Temperature Range2011In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 94, no 10, p. 3327-3334Article in journal (Refereed)
    Abstract [en]

    In this article, the reactivity of Ti(2)AlC powders, with 3 and 10 mu m alumina, Al(2)O(3), fibers during pressure-assisted sintering is explored. Samples were fabricated by hot-isostatic-pressing (HIPed) or hot-pressing (HPed), and characterized by X-ray diffraction, differential thermal analysis, and electron microscopy-both scanning and transmission-equipped with energy dispersive X-ray spectroscopes. Samples prepared at 1300 degrees C were fully dense, with no apparent reaction between fiber and matrix. In samples HPed to 1500 degrees C, even pure Ti(2)AlC powders dissociated to Ti(3)AlC(2) according to: 2 Ti(2)AlC = Ti(3)AlC(2) + TiAl(x) (l) + (1-x) Al (l/v), with x andlt; 1. More severe Al loss results in the formation of TiC(y). The presence of the Al(2)O(3) fibers delayed densification enough to allow most of the Al and some of the Ti to escape into the vacuum of the hot press or react with the encapsulating glass during HIPing a resulting in a more intensive dissociation of the Ti(2)AlC. Although, in principle Ti(2)AlC can be reinforced with Al(2)O(3) fibers, the processing/use temperature will have to be kept below 1500 degrees C, as, at that temperature the fibers, used here, sinter together.

  • 114.
    Abrikosov, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Knutsson, Axel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Tasnádi, Ferenc
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Lind, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Phase Stability and Elasticity of TiAlN2011In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 4, no 9, p. 1599-1618Article in journal (Refereed)
    Abstract [en]

    We review results of recent combined theoretical and experimental studies of Ti1−xAlxN, an archetypical alloy system material for hard-coating applications. Theoretical simulations of lattice parameters, mixing enthalpies, and elastic properties are presented. Calculated phase diagrams at ambient pressure, as well as at pressure of 10 GPa, show a wide miscibility gap and broad region of compositions and temperatures where the spinodal decomposition takes place. The strong dependence of the elastic properties and sound wave anisotropy on the Al-content offers detailed understanding of the spinodal decomposition and age hardening in Ti1−xAlxN alloy films and multilayers. TiAlN/TiN multilayers can further improve the hardness and thermal stability compared to TiAlN since they offer means to influence the kinetics of the favorable spinodal decomposition and suppress the detrimental transformation to w-AlN. Here, we show that a 100 degree improvement in terms of w-AlN suppression can be achieved, which is of importance when the coating is used as a protective coating on metal cutting inserts.

  • 115.
    Johansson, Emma
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Ballem, Mohamed
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Cordoba Gallego, Jose Manuel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Rapid Synthesis of SBA-15 Rods with Variable Lengths, Widths, and Tunable Large Pores2011In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 27, no 8, p. 4994-4999Article in journal (Refereed)
    Abstract [en]

    Dispersed SBA-15 rods have been synthesized with varying lengths, widths, and pore sizes in a low-temperature synthesis in the presence of heptane and NH4F. The pore size of the material can systematically be varied between 11 and 17 nm using different hydrothermal treatment times And/or temperatures. The particle length (400-600 nm) and width (100-400 nm) were tuned by varying the HCl concentration. All the synthesized materials possess a large surface area of 400-600 m(2)/g And a pore volume of 1.05-1.30 cm(3). A, mechanism for the effect of the HCl concentration on the particle morphology is suggested. Furthermore, it is shown that the reaction time an be decreased to 1 h, with well-retained pore size and morphology. This work has resulted in SBA-15 rods with the largest pore size reported for this morphology.

  • 116.
    Tsai, H T
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Cordoba Gallego, Jose Manuel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Johansson, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Ballem, Mohamed
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Silica SBA-15 Template Assisted Synthesis of Ultrasmall and Homogeneously Sized Copper Nanoparticles2011In: JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY, ISSN 1533-4880, Vol. 11, no 4, p. 3493-3498Article in journal (Refereed)
    Abstract [en]

    The synthesis of spherical copper nanoparticles with extremely narrow size distribution by electroless copper deposition on mesoporous silica support is described. The materials were characterized by nitrogen sorption, transmission electron microscopy, x-ray diffractometry and Fourier transform infrared spectroscopy. The copper nanoparticles have a cubic crystalline structure and an average particle size of 5.5 +/- 0.8 nm. The copper nanoparticles are stable, without detectable oxidation or further agglomeration under ambient conditions even after months. These results demonstrate that electroless copper reduction can be conducted and constrained within the mesoporous silica framework, which pave the way for engineered mesoreactors.

  • 117.
    Ballem, Mohamed
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Johansson, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Cordoba Gallego, Jose Manuel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Synthesis of hollow silica spheres SBA-16 with large-pore diameter2011In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 65, no 7, p. 1066-1068Article in journal (Refereed)
    Abstract [en]

    Hollow silica SBA-16 spheres with cubic ordered mesoporous shells were synthesized by an emulsion-templating method, using Pluronic F127 as a structure-directing agent. tetraethyl orthosilicateas as a silica source and heptane as a cosolvent in the presence of NH4F. The size of these spheres is in the range of 10 to 30 mu m. The shell is about 700 nm thick and consists of large pores, similar to 9 nm in diameter, arranged in a cubic order. After calcination, the spheres maintain their mesoporosity and show a high surface area of 822 m(2)/g. The formation mechanism of the silica hollow spheres is discussed.

  • 118.
    Spencer, Charles B
    et al.
    Drexel University.
    Cordoba Gallego, Jose Manuel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Obando, Nicholas H
    Texas AandM University.
    Radovic, Miladin
    Texas AandM University.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Barsoum, Michel W
    Drexel University.
    The Reactivity of Ti2AlC and Ti3SiC2 with SiC Fibers and Powders up to Temperatures of 1550 degrees C2011In: JOURNAL OF THE AMERICAN CERAMIC SOCIETY, ISSN 0002-7820, Vol. 94, no 6, p. 1737-1743Article in journal (Refereed)
    Abstract [en]

    The reactivities of commercially available Ti2AlC or Ti3SiC2 powders with uncoated SiC fibers or SiC powders were evaluated in this paper. When Ti2AlC-SiC samples were hot pressed or hot isostatically pressed at temperatures up to 1500 degrees C, fully dense composites were obtained. The latter were characterized by X-ray diffraction and electron-dispersive spectroscopy in a scanning and transmission electron microscope. Differential thermal analysis up to 1550 degrees C was also carried out. In all cases, SiC reacted with the Ti2AlC powder resulting in the formation of Ti-3(Al1-xSix)C-2 TiC and Al1+xTi1-x, where x ranges from 0 to 1. In the limit x=1, pure Al forms. Conversely, Ti3SiC2 samples, reinforced with uncoated SiC fibers or powders, can be hot pressed in vacuum at temperatures as high as 1500 degrees C to produce fully dense composites with no apparent reaction between the matrix and fibers. Based on these results, Ti3SiC2 can, but Ti2AlC cannot, be reinforced with SiC. Such reinforcements will be needed if the MAX phases are to be used as structural materials at very high temperatures.

  • 119.
    Eriksson, Anders
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Zhu, Jianqiang
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Ghafoor, Naureen
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Johansson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology. Seco Tools AB, Sweden.
    Sjölen, Jacob
    Seco Tools AB, Sweden.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Ti-Si-C-N Thin Films Grown by Reactive Arc Evaporation from Ti3SiC2 Cathodes2011In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 26, p. 874-881Article in journal (Refereed)
    Abstract [en]

    Ti-Si-C-N thin films were deposited onto WC-Co substrates by industrial scale arc evaporation from Ti3SiC2 compound cathodes in N2 gas. Microstructure and hardness were found to be highly dependent on the wide range of film compositions attained, comprising up to 12 at.% Si and 16 at.% C. Nonreactive deposition yielded films consisting of understoichiometric TiCx, Ti and silicide phases with high (27 GPa) hardness. At a nitrogen pressure of 0.25-0.5 Pa, below that required for N saturation, superhard, 45-50 GPa, (Ti,Si)(C,N) films with a nanocrystalline feathered structure were formed. Films grown above 2 Pa displayed crystalline phases of more pronounced nitride character, but with C and Si segregated to grain boundaries to form weak grain boundary phases. In abundance of N, the combined presence of Si and C disturb cubic phase growth severely and compromises the mechanical strength of the films.

  • 120.
    Rogström, Lina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Johnson, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Johansson, Mats P.
    SECO Tools AB, Fagersta, Sweden.
    Ahlgren, Mats
    Sandvik Tooling AB.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Age hardening in arc-evaporated ZrAlN thin films2010In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 62, no 10, p. 739-741Article in journal (Refereed)
    Abstract [en]

    Zr0.44Al0.56N1.20 films were deposited by reactive arc evaporation on WC-Co substrates. As-deposited films have a defect-rich NaCl-cubic and wurtzite phase mixture. During annealing at 1100 degrees C the films undergo simultaneous recovery of the ZrN-rich c-ZrAlN nanoscale domains and formation of semicoherent w-ZrAlN nanobricks, while the excess nitrogen is released. This process results in an age hardening effect as high as 36%, as determined by nanoindentation. At 1200 degrees C, the w-AlN recrystallizes and the hardening effect is lost.

  • 121.
    Zhu, Jianqiang
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Eriksson, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Ghafoor, Naureen
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Johansson, M P
    SECO Tools AB.
    Sjolen, J
    SECO Tools AB.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Characterization of worn Ti-Si cathodes used for reactive cathodic arc evaporation2010In: JOURNAL OF VACUUM SCIENCE and TECHNOLOGY A, ISSN 0734-2101, Vol. 28, no 2, p. 347-353Article in journal (Refereed)
    Abstract [en]

    The microstructural evolution of Ti1-xSix cathode surfaces (x=0, 0.1, 0.2) used in reactive cathodic arc evaporation has been investigated by analytical electron microscopy and x-ray diffractometry. The results show that the reactive arc operated in N-2 atmosphere induces a 2-12 mu m thick N-containing converted layer consisting of nanosized grains in the two-phase Ti and Ti5Si3 cathode surface. The formation mechanism of this layer is proposed to be surface nitriding and redeposition of macroparticles formed during the deposition process. The surface roughness of the worn Ti1-xSix cathodes increases with increasing Si content, up to 20 at. %, due to preferential erosion of Ti5Si3.

  • 122. Tamayo-Ariztondo, J.
    et al.
    Córdoba, José
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Molina-Aldareguia, J.M.
    IMDEA-Materiales, c/Profesor Aranguren, Madrid.
    Elizalde, M.R.
    University of Navarra.
    Effect of heat treatment of carbon nanofibres on electroless copper deposition2010In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 70, no 16, p. 2269-2275Article in journal (Refereed)
    Abstract [en]

    Cu is a well known heat sink material due to its high thermal conductivity. However, its coefficient of thermal expansion (CTE) is high. One of the most promising solutions for reducing it is to reinforce copper with carbon nanofibres (CNF) because of their low CTE. To exploit the properties of the CNFs a good dispersion of the reinforcement within the matrix must be achieved. One of the processing methods used to obtain a homogeneous CNF distribution is coating the CNF with Cu using electrochemical deposition. In this paper, the effect of the carbon structure on electroless deposition technique is studied. Different CNF have been compared: herringbone (HB), platelet (PL) and longitudinally aligned (previously heat treated) (LAHT). Herringbone and Platelet CNF were heat treated at 2750 °C for 30′ which resulted in a structure resembling graphite with loops at the fibre surface. These loops are responsible for an enhancement of the copper coating. It is shown that the Cu coverage in electroless deposition is high for the graphene plane and poor at the edges of the plane.

  • 123.
    Yazdi, Gholamreza
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Vassilevski, K.
    Newcastle University.
    Cordoba Gallego, Jose Manuel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Gogova, Daniela
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Nikitina, I. P.
    Newcastle University.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Wright, N.G.
    Newcastle University.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Free standing AIN single crystal grown on pre-patterned and in situ patterned 4H-SiC substrates2010In: Materials Science Forum, Vols. 645-648, Transtec Publications; 1999 , 2010, Vol. 645-648, p. 1187-1190Conference paper (Refereed)
    Abstract [en]

    Free standing AIN wafers were grown on pre-patterned and in situ patterned 4H-SiC substrates by a physical vapor transport method. It is based on the coalescence of AIN microrods, which evolve from the apex of SiC pyramids grown on the SIC substrate during a temperature ramp up for in situ patterned substrate and SiC pyramids formed by reactive ion etching (RIE). This process yields stress-free (according XRD and Raman results) AIN single crystals with a thickness up to 400 mu m and low dislocation density.

  • 124.
    Ballem, Mohamed A.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Córdoba, José M.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Influence of synthesis temperature on morphology of SBA-16 mesoporous materials with a three-dimensional pore system2010In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 129, p. 106-111Article in journal (Refereed)
    Abstract [en]

    Spherical particles of mesoporous silica SBA-16 with cubic Im3m structure were synthesized at low pH using Pluronic F127 as template and TEOS as silica source. The diameter of the spherical particles can be controlled in the range of 0.5–8 μm by varying synthesis temperature from 1 °C up to 40 °C. A sharp transition from large particle sizes at approximately 20 °C to smaller ones is observed when the temperature is increased. It is suggested that this morphology transition is due to a change in hydrolysis and condensation rate of the silica source and as a result the assembly of F127 micelles will differ. The SBA-16 samples were characterized using powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption techniques.

  • 125.
    Hedström, Peter
    et al.
    Luleå University of Technology.
    Han, Tong-Seok
    Yonsei University.
    Almer, Jonathan
    Argonne National Laboratory.
    Lienert, Ulrich
    Argonne National Laboratory.
    Odén, Magnus
    Luleå University of Technology.
    Load partitioning between single bulk grains in a two-phase duplex stainless steel during tensile loading2010In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 58, p. 734-744Article in journal (Refereed)
    Abstract [en]

    The lattice strain tensor evolution for single bulk grains of austenite and ferrite in a duplex stainless steel during tensile loading to 0.02 applied strain has been investigated using in situ high-energy X-ray measurements and finite-element modeling. Single-grain X-ray diffraction lattice strain data for the eight austenite and seven ferrite grains measured show a large variation of residual lattice strains, which evolves upon deformation to the point where some grains with comparable crystallographic orientations have lattice strains different by 1.5 × 10−3, corresponding to a stress of 300 MPa. The finite-element simulations of the 15 measured grains in three different spatial arrangements confirmed the complex deformation constraint and importance of local grain environment.

  • 126.
    Stjernberg, J.
    et al.
    Luleå Unverisity of Technology.
    Lindblom, B.
    Lulea Unverisity of Technology.
    Wikström, J.
    Lulea Unverisity of Technology.
    Antti, M.-L.
    Lulea Unverisity of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Microstructural characterization of alkali metal mediated high temperature reactions in mullite based refractories2010In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 36, p. 733-740Article in journal (Refereed)
    Abstract [en]

    Two types of refractory bricks were used in reaction tests with slag from a production kiln for iron ore pellet production. Electron microscopy was used to characterize morphological changes at the slag/brick interface and active chemical reactions. Phases such as kalsilite, nepheline and potassium β-alumina form, in a layered structure, as a consequence of alkali metals migration in the brick. Larger hematite grains (50–100 μm) in the slag remain at the original slag/brick interface, while smaller grains dissolve and move through the partly dissolved brick bulk, and forms micrometer sized needle-shaped crystals deeper in the lining material. Thermodynamic simulations predict the formation of a solid solution between hematite and corundum which is also observed in the reaction zone after extended time periods.

  • 127.
    Johnson, Lars
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Rogström, Lina
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Johansson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Microstructure evolution and age hardening in (Ti,Si)(C,N) thin films deposited by cathodic arc evaporation2010In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, no 4, p. 1397-1403Article in journal (Refereed)
    Abstract [en]

    Ti1 − xSixCyN1 − y films have been deposited by reactive cathodic arc evaporation onto cemented    carbide substrates. The films were characterized by X-ray diffraction, elastic recoil detection analysis, transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron-energy loss spectroscopy and nanoindentation. Reactive arc evaporation in a mixed CH4 and N2 gas gave    films with 0 ≤ x ≤ 0.13 and 0≤y≤0.27. All films had the NaCl-structure with a dense columnar microstructure, containing a featherlike pattern of nanocrystalline grains for high Si and C contents. The film hardness was 32–40GPa. Films with x > 0 and y > 0 exhibited age-hardening up to 35–44 GPa when isothermally annealed up to 900 °C. The temperature threshold for over-ageing was decreased to 700 °C with increasing C and Si content, due to migration of Co, W and Cr from the substrate to the film, and loss of Si. The diffusion pathway was tied to grain boundaries provided by the featherlike substructure.

  • 128.
    Tasnádi, Ferenc
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Rogström, Lina
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Almer, Jonathan
    Argonne National Laboratory, Illinois, USA.
    Johansson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Significant elastic anisotropy in Ti1−xAlxN alloys2010In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 97, no 23, p. 231902-231904Article in journal (Refereed)
    Abstract [en]

    Strong compositional-dependent elastic properties have been observed theoretically and experimentally in Ti1−xAlxN alloys. The elastic constant, C11, changes by more than 50% depending on the Al-content. Increasing the Al-content weakens the average bond strength in the local octahedral arrangements resulting in a more compliant material. On the other hand, it enhances the directional (covalent) nature of the nearest neighbor bonds that results in greater elastic anisotropy and higher sound velocities. The strong dependence of the elastic properties on the Al-content offers new insight into the detailed understanding of the spinodal decomposition and age hardening in Ti1−xAlxN alloys.

  • 129.
    Johansson, Emma
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Cordoba Gallego, Jose Manuel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    The effects on pore size and particle morphology of heptane additions to the synthesis of mesoporous silica SBA-152010In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 133, no 01-Mar, p. 66-74Article in journal (Refereed)
    Abstract [en]

    The effect of heptane on the particle morphology and pore size in the synthesis of SBA-15 is presented. Heptane in the presence of NH4F works as a pore swelling agent, resulting in 13-18 nm sized pores in 400 nm long and 200-1000 nm wide crystallites. The pores are hexagonally arranged and run through the crystallites. Increasing the heptane to P123 molar ratio changes the morphology of SBA-15 from fibers to sheets when the crystallites rearrange during the synthesis. The pore order in the sheets is controlled by changing the molar ratio of water to P123. The surface areas of these materials are 500-800 m(2)/g with pore volumes of 1.2-1.7 cm(3)/g. The sheets have accessible pores with a size of 18 nm running parallel to the sheet normal, which makes them suitable for membranes.

  • 130.
    Rogström, Lina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Johnson, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Johansson, Mats
    SECO Tools AB, Fagersta.
    Ahlgren, Mats
    Sandvik Tooling AB, Stockholm.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Thermal stability and mechanical properties of arc evaporated ZrN/ZrAlN multilayers2010In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, no 2, p. 694-699Article in journal (Refereed)
    Abstract [en]

    ZrN1.20/Zr0.44Al0.56N1.20 multilayer films as well as ZrN1.17 and Zr0.44Al0.56N1.20 films were deposited by reactive arc evaporation on WC–Co substrates. Samples were post-deposition annealed for 2 h at 800–1200 °C. As-deposited and heat treated films were characterized by scanning transmission electron microscopy, X-ray diffraction and nanoindentation. The thermal stability was studied using a combination of differential scanning calorimetry, thermogravimetry, and mass spectrometry. The as-deposited Zr0.44Al0.56N1.20 film exhibits a nanocomposite structure of cubic and wurtzite ZrAlN. During annealing, the formation of ZrN- and AlN-rich domains results in age hardening of both the Zr0.44Al0.56N1.20 and the ZrN/ZrAlN multilayers. The age hardening is enhanced in the ZrN/ZrAlN multilayer due to straining of the ZrAlN sublayers in which a maximum hardness of 31 GPa is obtained after annealing at 1100 °C.

  • 131.
    Knutsson, Axel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Johansson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Karlsson, L
    Seco Tools AB.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Thermally enhanced mechanical properties of arc evaporated Ti0.34Al0.66N/TiN multilayer coatings2010In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 108, no 4, p. 044312-Article in journal (Refereed)
    Abstract [en]

    Cubic metastable Ti0.34Al0.66N/TiN multilayer coatings of three different periods, 25+50, 12+25, and 6+12 nm, and monoliths of Ti0.34Al0.66N and TiN where grown by reactive arc evaporation. Differential scanning calorimetry reveals that the isostructural spinodal decomposition to AlN and TiN in the multilayers starts at a lower temperature compared to the monolithic TiAlN, while the subsequent transformation from c-AlN to h-AlN is delayed to higher temperatures. Mechanical testing by nanoindentation reveals that, despite the 60 vol % TiN, the as-deposited multilayers show similar or slightly higher hardness than the monolithic Ti0.34Al0.66N. In addition, the multilayers show a more pronounced age hardening compared to the monolith. The enhanced hardening phenomena and improved thermal stability of the multilayer coatings are discussed in terms of particle confinement and coherency stresses from the neighboring TiN-layers.

  • 132.
    Ullbrand, Jennifer
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Córdoba, José
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Tamayo-Ariztondo, J.
    Elizalde, M.R.
    Mats, Nygren
    University of Stockholm.
    Molina-Aldareguia, J.M.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Thermomechanical properties of copper–carbon nanofibre composites prepared by spark plasma sintering and hot pressing2010In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 70, no 16, p. 2263-2268Article in journal (Refereed)
    Abstract [en]

    Several types of carbon nanofibres (CNF) were coated with a uniform and dense copper layer by electroless copper deposition. The coated fibres were then sintered by two different methods, spark plasma sintering (SPS) and hot pressing (HP). The Cu coating thickness was varied so that different volume fraction of fibres was achieved in the produced composites. In some cases, the CNF were pre-coated with Cr for the improvement the Cu adhesion on CNF. The results show that the dispersion of the CNF into the Cu matrix is independent of the sintering method used. On the contrary, the dispersion is directly related to the efficiency of the Cu coating, which is tightly connected to the CNF type. Overall, strong variations of the thermal conductivity (TC) of the composites were observed (20–200 W/mK) as a function of CNF type, CNF volume fraction and Cr content, while the coefficient of thermal expansion (CTE) in all cases was found to be considerably lower than Cu (9.9–11.3 ppm/K). The results show a good potential for SPS to be used to process this type of materials, since the SPS samples show better properties than HP samples even though they have a higher porosity, in applications where moderate TC and low CTE are required.

  • 133.
    Stjernberg, Jesper
    et al.
    Luleå University Technology.
    Antti, Marta-Lena
    Luleå University Technology.
    Nordin, Lars-Olof
    LKAB.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Degradation of Refractory Bricks Used as Thermal Insulation in Rotary Kilns for Iron Ore Pellet Production2009In: INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, ISSN 1546-542X, Vol. 6, no 6, p. 717-726Article in journal (Refereed)
    Abstract [en]

    Degradation of bricks in an iron ore pellet producing kiln has been investigated. Lab-scale tests of brick/slag interaction performed under different temperatures, atmospheres, and alkali additions show that addition of alkali dissolves the mullite in the brick and leads to formation of the phase nepheline (Na2O center dot Al2O3 center dot 2SiO(2)). At a high temperature, the grain boundary where nepheline is formed disintegrates due to volume expansion. At increased temperature, the nepheline transforms to an amorphous phase. Thus, a wear mechanism is proposed in the kiln using these bricks that involves these chemical reactions in combination with erosion by the continuously flowing slag.

  • 134.
    Johanne, Mouzon
    et al.
    Luleå University of Technology.
    Alexandre, Maitre
    UMR CNRS .
    Lars, Frisk
    Luleå University of Technology.
    Niklas, Lehto
    Luleå University of Technology.
    Odén, Magnus
    Luleå University of Technology.
    Fabrication of transparent yttria by HIP and the glass-encapsulation method2009In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 29, no 2, p. 311-316Article in journal (Refereed)
    Abstract [en]

     This method consists of a combination of vacuum sintering at 1600 ◦C followed by hot isostatic pressing (HIP) at 1500 ◦C of a highly agglomerated commercial powder. The use of evacuated glass capsules to perform HIP treatment allowed samples that showed open porosity after vacuum sintering to be sintered to transparency. The sintering response of the investigated powder was studied by careful microstructural observations using scanning electron microscopy and optical microscopy both in reflection and transmission. The successful key of this method was to keep porosity intergranular during pre-sintering, so that it can be removed subsequently by HIP treatment. It was found that agglomerates of closely packed particles are helpful to reach that purpose, since they densify fully and leave only intergranular porosity. However, performing HIP treatment at 1625 ◦C was found to result in opaque samples. This was attributed to the diffusion of argon inside the capsule. Contamination at different steps of processing was also investigated by inductively coupled plasma mass spectrometry (ICP-MS).

  • 135.
    Cordoba Gallego, Jose Manuel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Growth and characterization of electroless deposited Cu films on carbon nanofibers2009In: SURFACE and COATINGS TECHNOLOGY, ISSN 0257-8972, Vol. 203, no 22, p. 3459-3464Article in journal (Refereed)
    Abstract [en]

    Carbon nanofibers with two different microstructures, herringbone and platelet have been used as substrates to study the influence of electroless deposition parameters on the growth of Cu deposits. Flat glassy carbon and graphite powder substrates were also included in the study for comparison. Samples were analyzed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, FT-IR, and energy dispersive X-ray spectroscopy in terms of microstructure and chemical composition. The specific surface area was determined by sorption techniques. High quality copper films can be grown on carbon nanofibers at room temperature if carbon nanofibers pretreatment is properly adjusted. The optimized process is easily up scaled to larger batches of carbon nanofibers.

  • 136.
    Oden, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Rogström, Lina
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Knutsson, Axel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Terner, M R
    Luleå University.
    Hedstrom, P
    Lulea University.
    Almer, J
    Argonne National Laboratory.
    Ilavsky, J
    Argonne National Laboratory.
    In situ small-angle x-ray scattering study of nanostructure evolution during decomposition of arc evaporated TiAlN coatings2009In: APPLIED PHYSICS LETTERS, ISSN 0003-6951, Vol. 94, no 5, p. 053114-Article in journal (Refereed)
    Abstract [en]

    Small-angle x-ray scattering was used to study in situ decomposition of an arc evaporated TiAlN coating into cubic-TiN and cubic-AlN particles at elevated temperature. At the early stages of decomposition particles with ellipsoidal shape form, which grow and change shape to spherical particles at higher temperatures. The spherical particles grow at a rate of 0.18 A/degrees C while coalescing.

  • 137.
    Hedstrom, P
    et al.
    Luleå University of Technology.
    Lindgren, L E
    Luleå University of Technology.
    Almer, J
    Argonne National Laboratory.
    Lienert, U
    Argonne National Laboratory.
    Bernier, J
    Lawrence Livermore National Laboratory.
    Terner, M
    Luleå University of Technology.
    Odén , Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Load Partitioning and Strain-Induced Martensite Formation during Tensile Loading of a Metastable Austenitic Stainless Steel2009In: METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, ISSN 1073-5623 , Vol. 40A, no 5, p. 1039-1048Article in journal (Refereed)
    Abstract [en]

    In-situ high-energy X-ray diffraction and material modeling are used to investigate the strain-rate dependence of the strain-induced martensitic transformation and the stress partitioning between austenite and alpha martensite in a metastable austenitic stainless steel during tensile loading. Moderate changes of the strain rate alter the strain-induced martensitic transformation, with a significantly lower alpha martensite fraction observed at fracture for a strain rate of 10(-2) s(-1), as compared to 10(-3) s(-1). This strain-rate sensitivity is attributed to the adiabatic heating of the samples and is found to be well predicted by the combination of an extended Olson-Cohen strain-induced martensite model and finite-element simulations for the evolving temperature distribution in the samples. In addition, the strain-rate sensitivity affects the deformation behavior of the steel. The alpha martensite transformation at high strains provides local strengthening and extends the time to neck formation. This reinforcement is witnessed by a load transfer from austenite to alpha martensite during loading.

  • 138.
    R.V., Mangalaraja
    et al.
    University of Concepción.
    J., Mouzon
    Luleå University of Technology.
    P., Hedström
    Luleå University of Technology.
    Carlos P., Camurri
    University of Concepción.
    S., Ananthakumar
    Université Montpellier 2.
    Odén, Magnus
    Luleå University of Technology.
    Microwave assisted combustion synthesis of nanocrystalline yttria and its powder characteristics2009In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 191, no 3, p. 309-314Article in journal (Refereed)
    Abstract [en]

     Microwave assisted combustion synthesis is used for fast and controlled processing of advanced ceramics. Single phase and sinter active nanocrystalline cubic yttria powders were successfully synthesized by microwave assisted combustion using the organic fuels urea, citric acid and glycine as reducing agents. The precursor powders were investigated by thermogravimetry (TG) and differential scanning colorimetry (DSC) analyses. The asprepared precursors and the resulting oxide powders calcined at 1100°C in oxygen atmosphere were characterized for their structure, particle size and morphology. The thermal analyses (TG/DSC), X-ray diffraction (XRD) and Fourier transform infra red (FTIR) results demonstrate the effectiveness of the microwave assisted combustion synthesis. The scanning electron microscopy (SEM) observations show the different morphologies of as-prepared powders and transmission electron microscopy (TEM) shows the particle sizes in the range of 30-100nm for calcined powders for different fuels. The results confirm that the homogeneous, nano scale yttria powders derived by microwave assisted combustion have high crystalline quality and the morphology of the as-prepared precursor powders depends on the nature of organic fuel used.

  • 139.
    Cordoba Gallego, Jose Manuel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Tamayo-Ariztondo, J
    Tecnun University Navarra.
    Molina-Aldareguia, J M
    Fdn IMDEA Mat.
    Elizalde, M R
    Tecnun University Navarra.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Morphology influence of the oxidation kinetics of carbon nanofibers2009In: CORROSION SCIENCE, ISSN 0010-938X, Vol. 51, no 4, p. 926-930Article in journal (Refereed)
    Abstract [en]

    This paper reports the stability and oxidation rate of five types of carbon nanofiber (CNF) with distinctly different orientation of their graphite sheets based on conversion to CO2 when heated in the presence of oxygen. A non-isothermal technique was used to determine the oxidation kinetic parameters including the activation energy (E-a) Graphite shows a similar activation energy (E-a = 158 kJ/mol(-1)) to CNF with longitudinal alignment (E-a = 156kJ/mol(-1)). CNF type herringbone (E-a = 126kJ/mol(-1)) and platelet (E-a = 145 kJ/mol(-1)) show the lowest oxidation resistance which improved dramatically after a heat treatment at 3023 K of the herringbone (E-a = 216 kJ/mol(-1)) and platelet (E-a = 174 kJ/mol(-1)) structures.

  • 140.
    Amini, Shahram
    et al.
    Drexel University.
    Cordoba Gallego, Jose M
    Los Alamos National Laboratory.
    McGhie, Andrew R
    University of Pennsylvania.
    Ni, Chaoying
    University of Delaware.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Oden, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    On the Stability of Mg Nanograins to Coarsening after Repeated Melting2009In: NANO LETTERS, ISSN 1530-6984, Vol. 9, no 8, p. 3082-3086Article in journal (Refereed)
    Abstract [en]

    Herein we report on the extraordinary thermal stability of similar to 35 nm Mg-nanograins that constitute the matrix of a Ti2AlC-Mg composite that has previously been shown to have excellent mechanical properties. The microstructure is so stable that heating the composite three times to 700 degrees C, which is 50 degrees C over the melting point of Mg, not only resulted in the repeated melting of the Mg, but surprisingly and within the resolution of our differential scanning calorimeter, did not lead to any coarsening. The reduction in the Mg melting point due to the nanograins was similar to 50 degrees C. X-ray diffraction and neutron spectroscopy results suggest that thin, amorphous, and/or poorly crystallized rutile, anatase, and/or magnesia layers separate the Mg nanograins and prevent them from coarsening. Clearly that layer is thin enough, and thus mechanically robust enough, to survive the melting and solidification stresses encountered during cycling. Annealing in hydrogen at 250 degrees C for 20 h, also did not seem to alter the grain size significantly.

  • 141.
    Kero, I.
    et al.
    Department of applied physics and mechanical engineering, Luleå University of Technology.
    Antti, M-L
    Department of applied physics and mechanical engineering, Luleå University of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Preparation and firing of a TiC/Si powder mixture2009In: IOP Conference Series-Materials Science and Engineering, ISSN 1757-8981, Vol. 5, p. 012016-Article in journal (Refereed)
    Abstract [en]

    This paper describes how the preparation and heat treatment of TiC/Sipowders influences the phase reactions during firing. The powders are prepared by milling andsome effects of powder preparation are discussed. A solid state displacement reactionaccording to: 3TiC + 2Si → Ti3SiC2 + SiC is a priori expected to take place during heattreatment. The firing procedure is investigated with respect to the effect of heat treatment timeand temperature on the phases produced, especially Ti3SiC2. Samples were heat treated in agraphite lined furnace. Heat treated samples are analysed by x-ray diffraction, scanningelectron microscope and energy dispersive spectroscopy. Ti3SiC2, TiC and SiC are dominant inthe final products. The highest amount of Ti3SiC2 is achieved for short holding times (2-4hours) at high temperatures (1350-1400ºC). Ti3SiC2 appears to decompose at elevatedtemperatures or extended times, through a Ti3SiC2 ® TiC + Si(g) type reaction. The activationenergy of Ti3SiC2 phase formation is determined to be 289 kJ/mol, using the Mehl-Avrami-Johnson model.

  • 142.
    Alling, Björn
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Pressure enhancement of the isostructural cubic decomposition in Ti1−xAlxN2009In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 95, no 181906Article in journal (Refereed)
    Abstract [en]

    The influence of pressure on the phase stabilities of Ti1−xAlxN solid solutions has been studied using first principles calculations. We find that the application of hydrostatic pressure enhances the tendency for isostructural decomposition, including spinodal decomposition. The effect originates in the gradual pressure stabilization of cubic AlN with respect to the wurtzite structure and an increased isostructural cubic mixing enthalpy with increased pressure. The influence is sufficiently strong in the composition-temperature interval corresponding to a shoulder of the spinodal line that it could impact the stability of the material at pressures achievable in the tool-work piece contact during cutting operations

  • 143.
    Mangalaraja, Ramalinga Viswanathan
    et al.
    University of Concepción, Chile.
    Ananthakumar, Solaiappan
    National Institute for Interdisciplinary Science and Technology (NIIST), CSIR, India.
    Mouzon, Johanne
    Luleå University of Technology.
    López, Marta
    University of Concepción, Chile.
    Camurri, Carlos Porro
    University of Concepción, Chile.
    Odén, Magnus
    Luleå University of Technology.
    Sintering, microstructural and mechanical characterization of combustion synthesized Y2O3 and Yb3+-Y2O32009In: Journal of the Ceramic Society of Japan, ISSN 1882-0743, Vol. 117, no 1371, p. 1258-1262Article in journal (Refereed)
    Abstract [en]

    The present work highlights the microstructural features and mechanical properties of Y2O3 prepared with and without Yb3+ doping that processed through combustion synthesis involving various organic fuels such as urea, citric acid and glycine. Properties such as powder-now, particle packing, green density, % of shrinkage, sintered density, grain size, Vicker's microhardness (H-v) and fracture toughness (K-IC) were analyzed and compared with respect to the fuel sources. The as combusted precursors were calcined at 1100 degrees C for 4 h under oxygen atmosphere to obtain fully crystalline Y2O3 powders. Cylindrical pellets were fabricated as test specimens and sintered at 1600 degrees C for 3 h. The SEM images of the sintered yttria samples show an average grain size of < 3 mu m irrespective of the fuels. However, the mechanical properties show significant dependence on the fuels used. A maximum hardness of 6.8 +/- 0.1 and 7.0 +/- 0.1 GPa was obtained for Y2O3 and Yb3+ doped Y2O3 derived from glycine fuel. Whereas the maximum fracture toughness of 2.6 +/- 0.3 MPa m(1/2) was obtained for the samples derived from urea. The Yb3+ doping found to increase the bulk hardness of yttria from 0.2 to 0.6 GPa. The study contributes to appropriately select the fuels for obtaining high dense, mechanically stable yttria ceramics through combustion process.

  • 144.
    Johansson, Emma
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Cordoba, Jose Manuel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Synthesis and characterization of large mesoporous silica SBA-15 sheets with ordered accessible 18 nm pores2009In: Materials Letters, ISSN 0167-577X, Vol. 63, no 24-25, p. 2129-2131Article in journal (Refereed)
    Abstract [en]

    Mesoporous silica SBA-15 in the form of 10-30 μm sized sheets with unusually large ordered pores has been synthesized using heptane as a cosolvent in the presence of NH4F. The resulting morphology of 400 nm thick sheets that contain easily accessed, hexagonally arranged, 18 nm sized pores running parallel to sheet normal has not been previously reported. The material has a BET surface area of 541 m2/g, large pore volume of 1.69 cm3/g and ordered mesopore structure with a narrow pore size distribution around 18 nm. A mechanism for sheet formation based on heptane droplets acting as sites for self assembling of silica crystallites is suggested.

  • 145.
    Antti, M.-L.
    et al.
    Luleå University of Technology.
    Cheng, Y.-B.
    Monash University.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Synthesis and phase development in the Ct-Al-N system2009In: Ceramic Engineering and Science Proceedings, vol 29, no 2, 2009, Vol. 29, no 2, p. 3-12Conference paper (Refereed)
    Abstract [en]

    The ternary nitride system Cr-Al-N has been investigated by sintering different powder compositions. The powder compositions belong to four groups, AIN- + Cr-powder (5 compositions between 20-90 molar% AlN), Al- + Cr 2N-powder (5 compositions between 15-80 molar% Cr2N), AlN-+ Cr2N-powder (50- and 90 molar% Cr2N) and Al- + Cr-powder. The powders were dry mixed and pressed into pellets by uniaxial pressing followed by cold isostatic pressing (ClP). Sintering took place in a graphite lined reaction bonding furnace under nitrogen atmosphere at three different temperatures, 1350C, 1500C and 1800C and in an alumina tube furnace in order to avoid access to carbon. Holding times were varied, from 2 hours up to 72 hours. The phase development was evaluated by thermal analysis and XRD. CrAlN was formed at 1350C but decomposed at higher temperatures. Both pure Al and Cr-powder were prone to react with carbon in the graphite furnace. Thermal analysis showed a sublimation of Cr2N at temperatures around 1050C and nitridation of pure Al-powder between 680-750C and of pure Cr-powder between 610-1080C. Samples with pure Al-powder showed a very large expansion due to melting of aluminium in combination with nitridation. AIN was found to be more stable than Cr 2N at higher temperatures and longer holding times. The mixtures of Al-+Cr-powder produced an intermediate Al-Cr-phase.

  • 146.
    Mangalaraja, Ramalinga Viswanathan
    et al.
    University of Concepción, Chile.
    Ananthakumar, Solaiappan
    National Institute ofr Interdisciplinary Science and Technology, India.
    Mouzon, Johanne
    Luleå University of Technology.
    Uma, Kasimayan
    Nagoya Institute of Technology.
    Lopéz, Marta
    University of Concepción, Chile.
    Camurri, Carlos Porro
    University of Concepción, Chile.
    Odén, Magnus
    Luleå University of Technology.
    Synthesis of nanocrystalline yttria through in-situ sulphated-combusion technique2009In: Nippon Seramikkusu Kyokai gakujutsu rombunshi, ISSN 0914-5400, E-ISSN 1882-1022, Vol. 117, no 1370, p. 1065-1068Article in journal (Refereed)
    Abstract [en]

    An in-situ sulphated-combustion reaction was conducted on the precursor mixture consisting of yttrium nitrate, organic fuels (urea, citric acid and glycine) and 10 mol% ammonium sulphate [(NH4)2SO4] at 500°C. Effect of sulphate addition on yttria particles morphology has been analyzed with respect to the types of fuels. In un-sulphated combustion, the calcined yttria powders showed rectangular particle morphology and low specific surface area. Whereas in sulphated-combustion spherical shaped yttria particles were achieved for glycine fuel. In the case of citric acid fuel, yttria powders with high specific surface area [26 m2/g] were obtained. For all the fuels, the sulphated-combustion reaction produced nanocrystalline yttria powders and they also had primary crystallite size below 4 nm in the as prepared conditions. Upon calcination at 1100°C, these powders attained mean particle size of 50 nm which was confirmed by TEM.

  • 147.
    Kero, I.
    et al.
    Luleå University of Technology.
    Antti, M.-L.
    Luleå University of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Synthesis of Ti3SiC2 by reaction of TiC and Si powders2009In: Ceramic Engineering and Science Proceedings, vol 29, no 2, 2009, Vol. 29, no 2, p. 21-30Conference paper (Refereed)
    Abstract [en]

    The MAX phase Ti3SiC2 has been synthesized from starting powder mixtures which do not include pure titanium. The presence of pure titanium in a powder is problematic because of its oxidizing, and in the form of a finely divided powder, explosive nature. The aim of this study was to evaluate the synthesis of bulk polycrystalline samples of Ti3SiC 2 from a starting powder mixture which is more suited for large scale production. Titanium silicon carbide MAX phase was synthesized by pressureless sintering of ball milled TiC and Si powders of six different compositions. The sintering reactions were evaluated in situ by dilatometer analysis under flowing argon gas. The as-sintered samples were evaluated using mainly x-ray diffraction (XRD) analysis. This study showed that titanium carbide, silicon carbide and titanium disilicide were present as intermediate or secondary phases in the samples. Our results indicate that TiSi2 is an intermediate phase to the formation of Ti3SiC2 when excess Si is present. The excess of silicon also proved beneficial for the synthesis of the MAX phase and there is a Si content which is optimal with respect to the maximum MAX phase content of the final product. The Ti3SiC2 was found to decompose into TiC and gaseous Si at high temperatures.

  • 148.
    Mangalaraja, R.V.
    et al.
    University of Concepción.
    Mouzon, J.
    Luleå University of Technology.
    Hedström, P.
    Luleå University of Technology.
    Kero, I.
    Luleå University of Technology.
    Ramam, K.V.S.
    University of Concepción.
    Camurri, Carlos P.
    University of Concepción.
    Odén, Magnus
    Luleå University of Technology.
    Combustion synthesis of Y2O3 and Yb-Y2O3 Part I. Nanopowders and their characterization2008In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 208, no 1-3, p. 415-422Article in journal (Refereed)
    Abstract [en]

     Nanosized yttrium oxide and ytterbium doped yttrium oxide powders were prepared by ceramic combustion techniques such as flash combustion, citrate gel decomposition and glycine combustion using urea, citric acid and glycine respectively as fuels. As synthesized precursors and calcined powders were characterized for their structural, particle size and morphology, and the optimization of calcination process by differential scanning calorimetry and thermal gravimetry. The thermal analyses together with XRD results demonstrate the effectiveness of the combustion process for the synthesis of pure phase nanocrystalline powders. Nanocrystalline pure yttria powders were obtained by the calcination of as-prepared precursors at 1100 ◦C for 4h.

  • 149.
    Mouzon, Johanne
    et al.
    Luleå University of Technology.
    Glowacki, Emily
    Luleå University of Technology.
    Oden, Magnus
    Luleå University of Technology.
    Comparison between slip-casting and uniaxial pressing for the fabrication of translucent yttria ceramics2008In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 43, no 8, p. 2849-2856Article in journal (Refereed)
    Abstract [en]

    Slip casting and uniaxial pressing were compared as first consolidation stages prior to cold isostatic pressing (CIP) to produce translucent yttria ceramics. In the first step, yttria slurries suitable for slip casting were prepared. The viscosity was optimized with respect to the starting agglomeration state, amount of dispersant, milling time, and number of milling balls. Secondly, pellets were prepared either by slip casting or uniaxial pressing and then cold-isostatically pressed. Finally, the pellets were made translucent by a combination of pre-sintering and hot isostatic pressing (HIP). Although slip-cast and pressed samples exhibited similar green-body densities after CIP and pre-sintering, the samples prepared by slip casting were more homogeneous in terms of translucency and microstructure throughout their bodies. This was attributed to the ability of slip casting to minimize density gradients during packing, and to the beneficial effect of ball-milling to remove larger agglomerates before casting. Therefore, slip casting as a first consolidation stage prior to CIP appears to be more suitable than uniaxial pressing in order to prepare homogeneous optical ceramics.

  • 150.
    Peter, Hedström
    et al.
    Division of Engineering Materials, Luleå University of Technology.
    Ulrich, Lienert
    Argonne National Laboratory.
    Jon, Almer
    Argonne National Laboratory.
    Odén, Magnus
    Luleå University of Technology.
    Elastic strain evolution and ε-martensite formation in individual austenite grains during in situ loading of a metastable stainless steel2008In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 62, no 2, p. 338-340Article in journal (Refereed)
    Abstract [en]

     The (hcp) ε-martensite formation and the elastic strain evolution of individual (fcc) austenite grains in metastable austenitic stainless steel AISI 301 has been investigated during in situ tensile loading up to 5% applied strain. The experiment was conducted using high-energy X-rays and the 3DXRD technique, enabling studies of individual grains embedded in the bulk of the steel. Out of the 47 probed austenite grains, one could be coupled with the formation of ε-martensite, using the reported orientation relationship between the two phases. The formation of ε-martensite occurred in the austenite grain with the highest Schmid factor for the active {111}b12¯1N slip system.

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