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TiAlN-based Coatings at High Pressures and Temperatures
Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

TiAlN and TiAlN-based coatings that are used of relevance as protection of cutting tool inserts used in metal machining have been studied. All coatings were deposited by reactive cathodic arc evaporation using industrial scale deposition systems. The metal content of the coatings was varied by using different combinations of compound cathodes. The as-deposited coatings were temperature annealed at ambient pressure and in some cases also at high pressure. The resulting microstructure was first evaluated through a combination of x-ray diffraction and transmission electron microscopy. In addition, mechanical properties such as hardness by nanoindentation were also reported.

TiAlN coatings with two different compositions were deposited on polycrystalline boron nitride substrates and then high pressure high temperature treated in a BELT press at constant 5.35 GPa and at 1050 and 1300 °C for different times.

For high pressure high temperature treated TiAlN it has been shown that the decomposition is slower at higher pressure compared to ambeint pressure and that no chemical interaction takes place between TiAlN and polycrystalline cubic boron nitride during the experiments. It is concluded that this film has the potential to protect a polycrystalline cubic boron nitride substrate during metal machining due to a high chemical integrity.

TiZrAlN coatings with different predicted driving forces for spinodal decomposition were furthermore annealed at different temperatures. For this material system it has been shown that for Zr-poor compositions the tendency for phase separation between ZrN and AlN is strong at elevated temperatures and that after spinodal decomposition stable TiZrN is formed.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2014. , 47 p.
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1690
Keyword [en]
Materials science; thin films; coatings; spinodal decomposition; TiAlN, TiZrAlN; HPHT; high pressure high temperature; BELT-press; transmission electron microscopy; x-ray diifraction; microhardness
National Category
Natural Sciences
URN: urn:nbn:se:liu:diva-112213DOI: 10.3384/lic.diva-112213Local ID: LIU-TEK.LIC-2014:122ISBN: 978-91-7519-186-7 (print)OAI: diva2:764293
2014-12-17, Röntgen, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 15:43 (English)
Knowledge Foundation
Available from: 2014-11-20 Created: 2014-11-18 Last updated: 2014-11-20Bibliographically approved
List of papers
1. High pressure and high temperature behaviour of TiAlN coatings deposited on c-BN based substrates
Open this publication in new window or tab >>High pressure and high temperature behaviour of TiAlN coatings deposited on c-BN based substrates
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

High pressure and temperature experiments of two different arc evaporated TiAlN alloys on polycrystalline cubic BN substrate reveal a strong influence of pressure on the decomposition rate of TiAlN. This pressure induced enhanced stability in combination with intact interface between the coatings and the substrate predicts enhanced endurance of TiAlN coated BN cutting tools.

Materials science; coatings; thin films; TiAlN; HPHT; spinodal decomposition; BELT-press
National Category
Physical Sciences Materials Engineering
urn:nbn:se:liu:diva-112212 (URN)

Available from: 2014-11-18 Created: 2014-11-18 Last updated: 2014-11-20Bibliographically approved
2. High temperature phase decomposition in TixZryAlzN
Open this publication in new window or tab >>High temperature phase decomposition in TixZryAlzN
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2014 (English)In: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 4, no 12, 127147-1-127147-9 p.Article in journal (Refereed) Published
Abstract [en]

Through a combination of theoretical and experimental observations we study the high temperature decomposition behavior of c-(TixZryAlzN) alloys. We show that for most concentrations the high formation energy of (ZrAl)N causes a strong tendency for spinodal decomposition between ZrN and AlN while other decompositions tendencies are suppressed. In addition we observe that entropic  effects due to configurational disorder favor a formation of a stable Zr-rich (TiZr)N phase with increasing temperature. Our calculations also predict that at high temperatures a Zr rich (TiZrAl)N disordered phase should become more resistant against the spinodal decomposition despite its high and positive formation energy due to the specific topology of the free energy surface at the relevant concentrations. Our experimental observations confirm this prediction by showing strong tendency towards decomposition in a Zr-poor sample while a Zr-rich alloy shows a greatly reduced decomposition rate, which is mostly attributable to binodal decomposition processes. This result highlights the importance of considering the second derivative of the free energy, in addition to its absolute value in predicting decomposition trends of thermodynamically unstable alloys.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2014
National Category
Physical Sciences
urn:nbn:se:liu:diva-110682 (URN)10.1063/1.4905138 (DOI)000347170100078 ()

On the day of the defence date the status of this article was Manuscript.

Available from: 2014-09-18 Created: 2014-09-18 Last updated: 2015-06-01Bibliographically approved

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