liu.seSearch for publications in DiVA
Change search
Refine search result
1 - 18 of 18
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Cabioch, Thierry
    et al.
    University of Poitiers.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Mauchamp, Vincent
    University of Poitiers.
    Jaouen, Michel
    University of Poitiers.
    Structural investigation of substoichiometry and solid solution effects in Ti2Al(C-x,N1-x)(y) compounds2012In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 32, no 8, p. 1803-1811Article in journal (Refereed)
    Abstract [en]

    The milling, cold compaction and thermal annealing (4 h-1400 degrees C-Ar flow) of Ti, TiC, Al and AlN powders were used to produce Ti2Al(CxN(1-x))(y) compounds with x = 0, 0.25, 0.5, 0.75, 1 and 0.7 andlt;= y andlt;= 1. X-ray diffraction analysis, scanning electron microscopy observations combined with microanalysis confirmed the formation of the almost pure Ti(2)A/CxN(1-x) carbonitrides for y=1 whereas increasing amounts of titanium aluminides were formed when y decreases. Proportions of the different phases deduced from Rietveld refinements of the X-ray diffractograms indicate that no or very poor substoichiometry in carbon was possible in carbide whereas C and N deficiency can be achieved in nitrides and carbonitrides Ti2AlCxN(1-x). Electron Energy Loss Spectroscopy investigations confirm that carbonitrides can have at least 20% of vacancies on the C or N site. The a lattice parameter varies linearly with x whereas it is not the case for the c lattice parameter, its values being lower for the carbonitrides. Furthermore, a strong broadening of the carbonitrides XRD peaks is observed, a phenomenon that can be mainly attributed to C and N concentration gradients inside the samples.

  • 2.
    Cabioch, Thierry
    et al.
    Université de Poitiers, France.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Mauchamp, Vincent
    Université de Poitiers, France.
    Jaouen, Michel
    Université de Poitiers, France.
    Barsoum, Michel W.
    Université de Poitiers, France and Drexel University, Philadelphia, USA.
    Tailoring of the thermal expansion of Cr2(Alx,Ge1−x)C phases2013In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 33, no 4, p. 897-904Article in journal (Refereed)
    Abstract [en]

    We report thermal expansion coefficients of the end members and solid-solution compounds in the Cr2(Alx,Ge1−x)C system. All samples studied were essentially phase-pure Cr2AlxGe1−xC except the Cr2GeC sample, which contained a substantial fraction of Cr5Ge3Cx. X-ray diffraction performed in the 25–800 °C temperature range shows that the in-plane thermal expansion remains essentially constant at about 14 ± 1 × 10−6 K−1 irrespective of Al content. The thermal expansion of the c axis decreases monotonically from 17 ± 1 × 10−6 K−1 for Cr2GeC to ∼12 ± 1 × 10−6 K−1 with increasing Al content. At around the Cr2(Al0.75,Ge0.25)C composition, the thermal expansion coefficients along the two directions are equal; a useful property to minimize thermal residual stresses. This study thus demonstrates that a solid-solution approach is a route for tuning a physical property like the thermal expansion. For completeness, we also include a structure description of the Cr5Ge3Cx phase, which has been reported before but is not well documented. Its space group is P63/mcm and its a and c lattice parameters are 7.14 Å and 4.88 Å, respectively. We also measured the thermal expansion coefficients of the Cr5Ge3Cx phase. They are found to be 16.3 × 10−6 K−1 and 28.4 × 10−6 K−1 along the a and c axes, respectively. Thus, the thermal expansion coefficients of Cr5Ge3Cx are highly anisotropic and considerably larger than those of the Cr2(Alx,Ge1−x)C phases.

  • 3.
    Cordoba Gallego, Jose Manuel
    et al.
    aInstituto de Ciencia de Materiales de Sevilla.
    Alcalá, M.D.
    aInstituto de Ciencia de Materiales de Sevilla.
    Avilés, M.A.
    aInstituto de Ciencia de Materiales de Sevilla.
    Sayagués, M.J.
    aInstituto de Ciencia de Materiales de Sevilla.
    Gotor, F.J.
    aInstituto de Ciencia de Materiales de Sevilla.
    New production of TiCxN1−x-based cermets by one step mechanically induced self-sustaining reaction: Powder synthesis and pressureless sintering2008In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 28, no 10, p. 2085-2098Article in journal (Refereed)
    Abstract [en]

     TiCxN1−x-based powdered cermets were synthesized by a one step mechanically induced self-sustaining reaction (MSR) process from mixtures of elemental powders, and subsequently sintered by a pressureless method. The composition and microstructure of the ceramic and binder phases before and after the sintering process were studied by X-ray diffraction, scanning and transmission electron microscopy, and electron diffraction. The powdered cermets showed excellent binder dispersion and a nanometer character for the ceramic and binder particles. The TiCxN1−x stoichiometry was consistently richer in carbon than expected from the raw powder composition. An important amount of titanium was present in the binder after MSR synthesis, and intermetallic Ti-Ni or Ti-Co phases were obtained in some cases. After sintering, the binder phase was always constituted by intermetallic compounds. The morphology of the ceramic phase in the final bodies was dependent on the C/N ratio of TiCxN1−x and its growth primarily occurred through a coalescence process. The presence of titanium in the binder reduced hard particle solubility in the melted binder and its grain growth.

  • 4.
    Frodelius, Jenny
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. 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.
    Paul, Dennis
    Phys Elect USA, USA .
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. 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.
    Phase stability and initial low-temperature oxidation mechanism of Ti2AlC thin films2013In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 33, no 2, p. 375-382Article in journal (Refereed)
    Abstract [en]

    Ti2AlC thin films deposited onto Al2O3 by magnetron sputtering were used as model for studying the early stages (andlt; 15 min) of relatively low-temperature (500 degrees C) oxidation of Ti2AlC. The well-defined microstructure of these films forms a surface of valleys, hillocks and plateaus comprised of basal-plane-oriented grains with a fraction of nonbasal-plane-oriented grains with out-of-plane orientation of (1 0 (1) over bar 3) and (1 0 (1) over bar 6) as shown by X-ray diffraction and s electron microscopy. During oxidation, Al2O3 clusters and areas of C-containing titania (TiOxCy) are formed on the surface. A mechanism is proposed in which the locations of the Al2O3 clusters are related to the migration of Al atoms diffusing out of Ti2AlC. The Al2O3 is initially formed in valleys or on plateaus where Al atoms have been trapped while TiOxCy forms by in-diffusion of oxygen into the Al-deficient Ti2AlC. At 500 degrees C, the migration of Al atoms is faster than the oxidation kinetics; explaining this microstructure-dependent oxidation mechanism.

  • 5.
    Halim, Joseph
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Drexel University, PA 19104 USA.
    Chartier, Patrick
    University of Poitiers, France.
    Basyuk, Tatyana
    National Academic Science Ukrain, Ukraine.
    Prikhna, Tatyana
    National Academic Science Ukrain, Ukraine.
    Caspi, Elad N.
    Nucl Research Centre Negev, Israel.
    Barsoum, Michel W.
    Drexel University, PA 19104 USA.
    Cabioch, Thierry
    University of Poitiers, France.
    Structure and thermal expansion of (Cr-x,V1-x)(n+1)AlCn phases measured by X-ray diffraction2017In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 37, no 1, p. 15-21Article in journal (Refereed)
    Abstract [en]

    MAX phases in the (Crx,V1-x)(n+1)AlCn,system were synthesized by reactive sintering or hot isostatic pressing of elemental powders at temperatures between 1400 degrees C and 1600 degrees C. For n=1, a complete range (0 amp;lt;= x amp;lt;= 1) of solid solutions was found; for n=2 and 3 the solubility ranges were 0.25 amp;lt;= x amp;lt;= 0.75 and 0 amp;lt;= x amp;lt;= 0.5, respectively. Powder X-ray diffraction revealed that the lattice parameters of all (Cr-x,V1-x)(n+1)AlCn solid solutions followed Vegards law. The thermal expansion coefficients of the various compounds were determined from Rietveld refinements of X-Ray patterns obtained at temperatures between ambient and 800 degrees C. For the n=1 and 3 phases the thermal expansion coefficients were almost isotropic; those for the n=2, however, were quite anisotropic with the expansion along the a-axis being significantly larger than along the c-axis. As a general trend, vanadium rich compounds have smaller thermal expansion coefficients than their Cr-rich counterparts. (C) 2016 Elsevier Ltd. All rights reserved.

  • 6.
    Ivanova, Mariya E.
    et al.
    Forschungszentrum Julich GmbH, Julich, Germany.
    Meulenberg, Wilhelm A.
    Forschungszentrum Julich GmbH, Julich, Germany.
    Palisaitis, Justinas
    Forschungszentrum Julich GmbH, Julich, Germany.
    Sebold, Doris
    Forschungszentrum Julich GmbH, Julich, Germany.
    Solís, Cecilia
    Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Valencia.
    Ziegner, Mirko
    Forschungszentrum Julich GmbH, Julich, Germany.
    Serra, Jose M.
    Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Valencia.
    Mayer, Joachim
    Forschungszentrum Julich GmbH, Julich, Germany.
    Hänsel, Michael
    Forschungszentrum Julich GmbH, Julich, Germany.
    Guillon, Olivier
    Forschungszentrum Julich GmbH, Julich, Germany.
    Functional properties of La0.99X0.01Nb0.99Al0.01O4−δ and La0.99X0.01Nb0.99Ti0.01O4−δ proton conductors where X is an alkaline earth cation2015In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 35, no 4, p. 1239-1253Article in journal (Refereed)
    Abstract [en]

    Lanthanum niobates with general formulas of La0.99X0.01Nb0.99Al0.01O4−δ and La0.99X0.01Nb0.99Ti0.01O4−δ (X = Mg, Ca, Sr or Ba) were synthesized via the conventional solid state reaction. Specimens with relative density above 96% were produced after sintering. Structural and phase composition studies revealed predominant monoclinic Fergusonite structure for the majority of samples. SEM and TEM studies elucidated the effect of the used dopant combinations on grain growth, micro-crack formation and secondary phase formation. Results from microstructural study were correlated to the grain interior and grain boundary conductivities for selected samples (La0.99Sr0.01Nb0.99Al0.01O4−δ and La0.99Sr0.01Nb0.99Ti0.01O4−δ). The majority of co-doped niobates exhibited appreciable protonic conductivity under humid atmospheres at intermediate temperatures. Sr- or Ca-doped compounds displayed the highest total conductivities with values for LSNA equal to 6 × 10−4 S/cm and 3 × 10−4 S/cm in wet air and in wet 4% H2–Ar (900 °C), respectively. Additionally, thermal expansion was studied to complete functional characterization of co-doped LaNbO4.

  • 7.
    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).

  • 8.
    Jonnalagadda, Krisha Praveen
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Yuan, Kang
    Beijing Gen Research Institute Min and Met, Peoples R China.
    Li, Xin-Hai
    Siemens Ind Turbomachineiy AB, Sweden.
    Ji, Xiaojuan
    Beijing Gen Research Institute Min and Met, Peoples R China.
    Yu, Yueguang
    Beijing Gen Research Institute Min and Met, Peoples R China.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    A study of damage evolution in high purity nano TBCs during thermal cycling: A fracture mechanics based modelling approach2017In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 37, no 8, p. 2889-2899Article in journal (Refereed)
    Abstract [en]

    This work concerns the study of damage evolution in a newly developed high purity nano 8YSZ thermal barrier coating during thermal cyclic fatigue tests (TCF). TCF tests were conducted between 100 degrees C-1100 degrees C with a hold time of 1 hat 1100 degrees C, first till failure and later for interrupted tests. Cross section analysis along the diameter of the interrupted test samples revealed a mixed-type failure and that the most of the damage occurred towards the end of the coatings life. To understand the most likely crack growth mechanism leading to failure, different crack growth paths have been modelled using finite element analysis. Crack growing from an existing defect in the top coat towards the top coat/TGO interface has been identified as the most likely mechanism. Estimated damage by the model could predict the rapid increase in the damage towards the end of the coatings life. (C) 2017 Elsevier Ltd. All rights reserved.

  • 9.
    Jonnalagadda, Krishna Praveen
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Arts and Sciences.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, 61283, Finspång, Sweden.
    Peng, Ru Lin
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Fatigue life prediction of thermal barrier coatings using a simplified crack growth model2019In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 39, no 5, p. 1869-1876Article in journal (Refereed)
    Abstract [en]

    Models that can predict the life of thermal barrier coatings (TBCs) during thermal cycling fatigue (TCF) tests are highly desirable. The present work focuses on developing and validating a simplified model based on the relation between the energy release rate and the TCF cycles to failure. The model accounts for stresses due to thermal mismatch, influence of sintering, and the growth of TGO (alumina and other non-protective oxides). The experimental investigation of TBCs included; 1) TCF tests at maximum temperatures of 1050 °C, 1100 °C, 1150 °C and a minimum temperature of 100 °C with 1 h and 5 h (1100 °C) hold times. 2) Isothermal oxidation tests at 900, 1000 and 1100 °C for times up to 8000 h. The model was calibrated and validated with the experimental results. It has been shown that the model is able to predict the TCF life and effect of hold time with good accuracy.

  • 10.
    Käll, Per-Olov
    et al.
    University of Stockholm.
    Ekström, Thommy
    University of Stockholm.
    Sialon Ceramics Made with Mixtures of Y2O3-Nd2O3 as Sintering Aid1990In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 6, no 2, p. 119-127Article in journal (Refereed)
    Abstract [en]

    Sialon ceramics have been prepared by pressureless sintering at 1775 and 1825°C, using mixtures of Y2O3---Nd2O3 as sintering aids. It was found that at 1775°C less dense materials were obtained, but by raising the sintering temperature to 1825°C fully dense materials could be produced, even when pure neodymia was used. The hardness of the Nd-sialon ceramics was found to be slightly lower than for the corresponding Y-sialon ceramics, but the fracture toughness was approximately the same. It was also observed that the amount of intergranular phase increased when yttria was replaced by neodymia.

  • 11.
    Lane, Nina J.
    et al.
    Drexel University, USA .
    Naguib, Michael
    Drexel University,USA .
    Lu, Jun
    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.
    Barsoum, Michel W.
    Drexel University, USA .
    Structure of a new bulk Ti5Al2C3 MAX phase produced by the topotactic transformation of Ti2AlC2012In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 32, no 12, p. 3485-3491Article in journal (Refereed)
    Abstract [en]

    Upon annealing cold-pressed Ti2AlC,-325 mesh powders, at 1500 degrees C for 8 h in argon, the resulting partially sintered sample contained 43(+/- 2) wt.% of the layered ternary carbide Ti5Al2C3. Herein, the X-ray powder diffraction pattern of Ti5Al2C3 is reported for the first time and its structure and stoichiometry are confirmed through high-resolution transmission electron microscopy. This phase has a trigonal structure (space group P3m1) with a unit cell consisting of 3 formula units and cell parameters of a=3.064 angstrom, c = 48.23 angstrom. The lattice parameters determined through first principles calculations agree reasonably well with the experimentally determined values. At 147.1 GPa, the calculated bulk modulus falls between the bulk moduli of Ti2AlC and Ti3AlC2. The transformation from Ti2AlC to Ti5Al2C3 is topotactic.

  • 12.
    Lapauw, T.
    et al.
    Katholieke University of Leuven, Belgium; CEN SCK, Belgium.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Drexel University, PA 19104 USA.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Cabioch, T.
    University of Poitiers, France.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Barsoum, Michel
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Drexel University, PA 19104 USA.
    Lambrinou, K.
    CEN SCK, Belgium.
    Vleugels, J.
    Katholieke University of Leuven, Belgium.
    Synthesis of the novel Zr3AlC2 MAX phase2016In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 36, no 3, p. 943-947Article in journal (Refereed)
    Abstract [en]

    Herein we report, for the first time, on the synthesis and structural characterization of the Zr-based MAX phase, Zr3AlC2, fabricated by reactive hot pressing of ZrH2, Al, and C powders. The crystal structure of Zr3AlC2 was determined by X-ray diffraction and high resolution transmission electron microscopy to be the hexagonal space group P63/mmc. The a and c lattice parameters are 3.33308(6)angstrom and 19.9507(3)angstrom, respectively. The samples include the secondary phases ZrC and Zr-Al intermetallics as confirmed by quantitative electron probe microanalysis. The Vickers hardness, using a force of 30 N, was measured to be 4.4 +/- 0.4 GPa. (C) 2015 Elsevier Ltd. All rights reserved.

  • 13.
    Lapauw, T.
    et al.
    Katholieke University of Leuven, Belgium; CEN SCK, Belgium.
    Lambrinou, K.
    CEN SCK, Belgium.
    Cabioch, T.
    University of Poitiers, France.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Drexel University, PA 19104 USA.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Pesach, A.
    Nucl Research Centre Negev, Israel.
    Rivin, O.
    Nucl Research Centre Negev, Israel.
    Ozeri, O.
    Soreq Nucl Research Centre, Israel.
    Caspi, E. N.
    Nucl Research Centre Negev, Israel.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Barsoum, Michel
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Drexel University, PA 19104 USA.
    Vleugels, J.
    Katholieke University of Leuven, Belgium.
    Synthesis of the new MAX phase Zr2AlC2016In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 36, no 8, p. 1847-1853Article in journal (Refereed)
    Abstract [en]

    This study reports on the first experimental evidence of the existence of the Zr2AlC MAX phase, synthesised by means of reactive hot pressing of a ZrH2, Al and C powder mixture. The crystal structure of this compound was investigated by X-ray and neutron diffraction. The lattice parameters were determined and confirmed by high-resolution transmission electron microscopy. The effect of varying the synthesis temperature was investigated, indicating a relatively narrow temperature window for the synthesis of Zr2AlC. ZrC was always present as a secondary phase by hot pressing in the 1475-1575 degrees C range.

  • 14.
    Mouzon, Johanne
    et al.
    Luleå University of Technology.
    Nordell, Patricia
    Luleå University of Technology.
    Thomas, Adrien
    Luleå University of Technology.
    Odén, Magnus
    Luleå University of Technology.
    Comparison of two different precipitation routes leading to Yb doped Y2O3 nano-particles2007In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 27, no 4, p. 1991-1998Article in journal (Refereed)
    Abstract [en]

    Two different precipitation routes leading to (YbxY1−x)2O3 nano-particles (with x = 0; 0.027; and 0.31) were compared, namely, precipitation of hydroxynitrate platelets and amorphous carbonate spherical particles. For both methods, the particle morphology was observed by scanning electron microscopy. X-ray diffraction studies of the unit cell, energy dispersive X-ray analysis and inductive coupled plasma spectroscopy were used to check the ytterbium distribution. The precipitation of amorphous carbonate was found to produce particles with uniform morphology and homogeneous distribution of ytterbium, while hydroxide precipitation favours the formation of hard and dense ytterbium-rich agglomerates. These differences are discussed in terms of precipitation, growth and agglomeration behaviour. The sinterability of both resulting powders is also discussed.

  • 15.
    Palisaitis, Justinas
    et al.
    Forschungszentrum Julich GmbH, Julich, Germany.
    Ivanova, Mariya E.
    Forschungszentrum Julich GmbH, Julich, Germany.
    Meulenberg, Wilhelm A.
    Forschungszentrum Julich GmbH, Julich, Germany.
    Guillon, Olivier
    Forschungszentrum Julich GmbH, Julich, Germany.
    Mayer, Joachim
    Forschungszentrum Julich GmbH, Julich, Germany.
    Phase homogeneity analysis of La0.99Sr0.01Nb0.99Al0.01O4−δ and La0.99Ca0.01Nb0.99Ti0.01O4−δ proton conductors by high-resolution STEM and EELS2015In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 35, no 5, p. 1517-1525Article in journal (Refereed)
    Abstract [en]

    The microstructural and compositional homogeneity of La0.99Ca0.01Nb0.99Ti0.01O4−δ and La0.99Sr0.01Nb0.99Al0.01O4−δ proton conductors was studied using the combination of atomic-resolution scanning transmission electron microscopy (STEM), electron energy loss spectroscopy (EELS) and STEM image simulations. The obtained results revealed that gently doped proton conductors were predominantly composed of grains with a monoclinic lanthanum niobate crystal structure. In addition to the host phase, dopant-rich phases were also observed and identified. The La0.99Sr0.01Nb0.99Al0.01O4−δ matrix accommodated dopant-rich grains retaining an LaAlO3 cubic crystal structure with a significant fraction of Sr incorporated into them. The secondary phases embedded in the La0.99Ca0.01Nb0.99Ti0.01O4−δ matrix possessed the pyrochlore La2Ti2O7 crystal structure with Ca partially substituting La. High spatial resolution EELS revealed preferential Ca sites within the pyrochlore La2Ti2O7 crystal lattice. The origin of the secondary phase formation and the role of these phases for the transport properties of co-doped lanthanum niobates are discussed here.

  • 16.
    Persson, Jeanette
    et al.
    Stockholms universitet.
    Ekström, Thommy
    Stockholms universitet.
    Käll, Per-Olov
    Stockholms universitet.
    Nygren, Mats
    Stockholms universitet.
    Oxidation Behaviour and Mechanical Properties of β- and Mixed α-β Sialons Sintered with Additions of Y2O3 and Nd2O31993In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 11, no 4, p. 363-373Article in journal (Refereed)
    Abstract [en]

    Sialon ceramics have been prepared from two different Si3N4 powders obtained from different commercial sources, using Y2O3 and/or Nd2O3 as sintering aid. Although both powders were high-purity and high-quality silicon nitrides, surprisingly different phase compositions were obtained for the same overall starting compositions upon sintering at 1825°C. The phase compositions, densities, microstructures and mechanical properties of the samples obtained from the two powders have been compared. The samples prepared from one of the powders were oxidized at 1350°C for 20 h in dry oxygen in a TG unit. The oxidation curves obtained have been interpreted within the framework of a new rate law. The new rate law covers the observation that the oxidation behaviour of Si3N4-based ceramics is often non-parabolic, probably as a result of crystallization processes and the formation of cracks and/or bubbles within the oxide scale or at the scale/matrix interface during oxidation.

  • 17.
    Persson, Jeanette
    et al.
    Stockholm University.
    Käll, Per-Olov
    Stockholm University.
    Nygren, Mats
    Stockholm University.
    Parabolic-Non-Parabolic Oxidation Kinetics of Si3N41993In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 12, no 3, p. 177-184Article in journal (Refereed)
    Abstract [en]

    The isothermal oxidation behaviour of Si3N4, HIP sintered without additives, has been investigated thermogravimetrically in the temperature range 1250–1500°C. The formed oxide scales were found to be partly crystalline, and the obtained weight gain curves followed the parabolic rate law after a certain time, t0, but not during the entire oxidation experiment. In the time interval t<t0 the curves have been interpreted with the rate law , which is developed with the assumption that the cross-section area available for oxygen diffusion decreases during the experiment, due to a crystallization process and to formation of nitrogen bubbles within the oxide scale. The rate constants, Kp were calculated from the constants in the arctan function, and the activation energy could be determined to be 310±25 kJ/mol. The oxygen diffusion rates found are in fair agreement with those obtained for amorphous silica.

  • 18.
    Stjernberg, Jesper
    et al.
    Luleå University of Technology.
    Ion, John C
    Luleå University of Technology.
    Antti, Marta-Lena
    Luleå University of Technology.
    Nordin, Lars-Olof
    LKAB.
    Lindblom, Bo
    LKAB.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Extended studies of degradation mechanisms in the refractory lining of a rotary kiln for iron ore pellet production2012In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 32, no 8, p. 1519-1528Article in journal (Refereed)
    Abstract [en]

    Changes, over a period of 8 years, in the chemical composition and morphology of deposit and lining materials in a production rotary kiln for iron ore pellet manufacture are described. The following have been studied: two types of refractory brick used as lining material; deposited chunk materials from the lining; the interaction zones between deposits and linings. Morphological changes at the deposit/lining interface, and the active chemical reactions, are established. Larger hematite grains in the deposit material (5-50 mu m) primarily remain at the original deposit/lining interface. The remainder penetrates fissures, voids and brick joints, forms a laminar structure with corundum from the bricks, and migrates in grains in the lining material. Potassium penetrates more deeply into the bricks than hematite, resulting in the formation of kalsilite, leucite and potassium beta-alumina, which contribute to degradation of the lining.

1 - 18 of 18
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf