liu.seSök publikationer i DiVA
Ändra sökning
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
α-alumina coatings on WC/Co substrates by physical vapor deposition
Sandvik Tooling, SE-126 80 Stockholm, Sweden.
Sandvik Tooling, SE-126 80 Stockholm, Sweden.
Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska högskolan.
Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska högskolan.ORCID-id: 0000-0002-1744-7322
2009 (Engelska)Ingår i: International journal of refractory metals & hard materials, ISSN 0958-0611, E-ISSN 2213-3917, Vol. 27, nr 2, s. 507-512Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Physical vapor deposition coatings for cutting tools may be deposited by, e.g. reactive magnetron sputtering. Alumina growth in Ar/O2 gas mixtures gives rise to problems due to insulating layers on targets, and hysteresis effects with respect to oxygen gas flow. In this paper is described a technology for the deposition of crystalline alumina: reactive high power impulse magnetron sputtering. Pure Al was used as target material, and the cemented carbide (WC/Co) substrates were kept at 500-650 ºC. Hysteresis effects with respect to oxygen gas flow were alleviated, which enabled stable growth at a high deposition rate. The high power impulses were helpful in obtaining a crystalline oxide coating. X-ray diffraction and crosssection transmission electron microscopy showed that α-alumina films were formed. Technological testing of these PVD alumina coatings, with state-of-the-art AlTiN as benchmark, showed significantly improved crater wear resistance in steel turning.

Ort, förlag, år, upplaga, sidor
2009. Vol. 27, nr 2, s. 507-512
Nyckelord [en]
HiPIMS, HPPMS, ionized-PVD, alumina, corundum
Nationell ämneskategori
Fysik
Identifikatorer
URN: urn:nbn:se:liu:diva-15359DOI: 10.1016/j.ijrmhm.2008.10.007OAI: oai:DiVA.org:liu-15359DiVA, id: diva2:114049
Anmärkning
On the day of defence date the status of article VII was: Accepted. Original Publication: T.I. Selinder, E. Coronel, Erik Wallin and Ulf Helmersson, α-alumina coatings on WC/Co substrates by physical vapor deposition, 2009, International journal of refractory metals & hard materials, (27), 2, 507-512. http://dx.doi.org/10.1016/j.ijrmhm.2008.10.007 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/ Tillgänglig från: 2009-02-23 Skapad: 2008-11-05 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
Ingår i avhandling
1. Alumina Thin Films: From Computer Calculations to Cutting Tools
Öppna denna publikation i ny flik eller fönster >>Alumina Thin Films: From Computer Calculations to Cutting Tools
2008 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

The work presented in this thesis deals with experimental and theoretical studies related to alumina thin films. Alumina, Al2O3, is a polymorphic material utilized in a variety of applications, e.g., in the form of thin films. However, controlling thin film growth of this material, in particular at low substrate temperatures, is not straightforward. The aim of this work is to increase the understanding of the basic mechanisms governing alumina growth and to investigate novel ways of synthesizing alumina coatings. The thesis can be divided into two main parts, where the first part deals with fundamental studies of mechanisms affecting alumina growth and the second part with more application-oriented studies of high power impulse magnetron sputter (HiPIMS) deposition of the material.

In the first part, it was shown that the thermodynamically stable α phase, which normally is synthesized at substrate temperatures of around 1000 °C, can be grown using reactive sputtering at a substrate temperature of merely 500 °C by controlling the nucleation surface. This was done by predepositing a Cr2O3 nucleation layer. Moreover, it was found that an additional requirement for the formation of the α phase is that the depositions are carried out at low enough total pressure and high enough oxygen partial pressure. Based on these observations, it was concluded that energetic bombardment, plausibly originating from energetic oxygen, is necessary for the formation of α-alumina (in addition to the effect of the chromia nucleation layer). Moreover, the effects of residual water on the growth of crystalline films were investigated by varying the partial pressure of water in the ultra high vacuum (UHV) chamber. Films deposited onto chromia nucleation layers exhibited a columnar structure and consisted of crystalline α-alumina if deposited under UHV conditions. However, as water to a partial pressure of 1*10-5 Torr was introduced, the columnar α-alumina growth was disrupted. Instead, a microstructure consisting of small, equiaxed grains was formed, and the γ-alumina content was found to increase with increasing film thickness.

To gain a better understanding of the atomistic processes occurring on the surface, density functional theory based computational studies of adsorption and diffusion of Al, O, AlO, and O2 on different α-alumina (0001) surfaces were also performed. The results give possible reasons for the difficulties in growing the α phase at low temperatures through the identification of several metastable adsorption sites and also show how adsorbed hydrogen might inhibit further growth of α-alumina crystallites. In addition, it was shown that the Al surface diffusion activation energies are unexpectedly low, suggesting that limited surface diffusivity is not the main obstacle for low-temperature α-alumina growth. Instead, it is suggested to be more important to find ways of reducing the amount of impurities, especially hydrogen, in the process and to facilitate α-alumina nucleation when designing new processes for low-temperature deposition of α-alumina.

In the second part of the thesis, reactive HiPIMS deposition of alumina was studied. In HiPIMS, a high-density plasma is created by applying very high power to the sputtering magnetron at a low duty cycle. It was found, both from experiments and modeling, that the use of HiPIMS drastically influences the characteristics of the reactive sputtering process, causing reduced target poisoning and thereby reduced or eliminated hysteresis effects and relatively high deposition rates of stoichiometric alumina films. This is not only of importance for alumina growth, but for reactive sputter deposition in general, where hysteresis effects and loss of deposition rate pose a substantial problem. Moreover, it was found that the energetic and ionized deposition flux in the HiPIMS discharge can be used to lower the deposition temperature of α-alumina. Coatings predominantly consisting of the α phase were grown at temperatures as low as 650 °C directly onto cemented carbide substrates without the use of nucleation layers. Such coatings were also deposited onto cutting inserts and were tested in a steel turning application. The coatings were found to increase the crater wear resistance compared to a benchmark TiAlN coating, and the process consequently shows great potential for further development towards industrial applications.

Ort, förlag, år, upplaga, sidor
Linköping: Linköping University Electronic Press, 2008. s. 59
Serie
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1221
Nyckelord
Alumina, thin films, coatings, sputtering, density functional theory, high power impulse magnetron sputtering, HIPIMS
Nationell ämneskategori
Övrig annan teknik Bearbetnings-, yt- och fogningsteknik Den kondenserade materiens fysik
Identifikatorer
urn:nbn:se:liu:diva-15360 (URN)978-91-7393-769-6 (ISBN)
Disputation
2008-11-27, Planck, Physics building, Campus Valla, Linköping University, Linköping, 10:15 (Engelska)
Opponent
Handledare
Tillgänglig från: 2008-11-05 Skapad: 2008-11-05 Senast uppdaterad: 2013-10-30Bibliografiskt granskad

Open Access i DiVA

fulltext(1996 kB)926 nedladdningar
Filinformation
Filnamn FULLTEXT01.pdfFilstorlek 1996 kBChecksumma SHA-512
40666915c487da5fb74d0ab4e34f45b706dfe1ce2ed0c8fabf489d0b823850e391d08bc233d94d5af41763779e4f5142f52b47bc8ee1e2aeaeacff5fcf5c1c75
Typ fulltextMimetyp application/pdf

Övriga länkar

Förlagets fulltextLink to Ph.D. Thesis

Personposter BETA

Wallin, ErikHelmersson, Ulf

Sök vidare i DiVA

Av författaren/redaktören
Wallin, ErikHelmersson, Ulf
Av organisationen
Plasma och beläggningsfysikTekniska högskolan
I samma tidskrift
International journal of refractory metals & hard materials
Fysik

Sök vidare utanför DiVA

GoogleGoogle Scholar
Totalt: 926 nedladdningar
Antalet nedladdningar är summan av nedladdningar för alla fulltexter. Det kan inkludera t.ex tidigare versioner som nu inte längre är tillgängliga.

doi
urn-nbn

Altmetricpoäng

doi
urn-nbn
Totalt: 1123 träffar
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf