TY - THES

T1 - Thermal stability and oxidation resistance of Ti-Al-N/Ta-Al-N multilayer coatings

AU - Koller, Christian

N1 - embargoed until 01-06-2017

PY - 2012

Y1 - 2012

N2 - Ambitious material development for surface protection has yielded in a wide variety of coatings, whose purpose is the enhanced resistance against mechanical and thermal failure. In respect of metal processing tools, Ti(1-x)Al(x)N hard coatings are well acknowledged and have until today successfully been investigated in terms of chemical and architectural modifications. The present study adopts the approach of alloying Tantalum (its beneficial attributes regarding high temperature performance have recently been proofed) and proceeds with structural adaptations and different deposition methods, which are of certain interest for industrial application. Ti(1-x)Al(x)N/Ta(1-y)Al(y)N (where x=Al/(Al+Ti) and y=Al/(Al+Ta) stand for the Al content of the individual layers) multilayer coatings were synthesised in an industrial scale deposition plant using two different deposition methods, reactive arc evaporation and reactive sputter deposition. For this purpose, powder-metallurgical Ti-Al and Ta-Al alloyed targets with chemical composition Ti(0.5)Al(0.5) and Ta(0.75)Al(0.25) respectively, were used for the deposition of protective films having a different build-up. The coatings' performance after vacuum annealing treatments at temperatures up to 1400°C was investigated by X-Ray diffraction and nanoindentation. The present results exhibit a strong influence of the bilayer period and Ta content on mechanical as well as thermal properties and consequently, on the age hardening, thermal stability and oxidation resistance of the Ti(1-x)Al(x)N/Ta(1-y)Al(y)N coatings investigated.

AB - Ambitious material development for surface protection has yielded in a wide variety of coatings, whose purpose is the enhanced resistance against mechanical and thermal failure. In respect of metal processing tools, Ti(1-x)Al(x)N hard coatings are well acknowledged and have until today successfully been investigated in terms of chemical and architectural modifications. The present study adopts the approach of alloying Tantalum (its beneficial attributes regarding high temperature performance have recently been proofed) and proceeds with structural adaptations and different deposition methods, which are of certain interest for industrial application. Ti(1-x)Al(x)N/Ta(1-y)Al(y)N (where x=Al/(Al+Ti) and y=Al/(Al+Ta) stand for the Al content of the individual layers) multilayer coatings were synthesised in an industrial scale deposition plant using two different deposition methods, reactive arc evaporation and reactive sputter deposition. For this purpose, powder-metallurgical Ti-Al and Ta-Al alloyed targets with chemical composition Ti(0.5)Al(0.5) and Ta(0.75)Al(0.25) respectively, were used for the deposition of protective films having a different build-up. The coatings' performance after vacuum annealing treatments at temperatures up to 1400°C was investigated by X-Ray diffraction and nanoindentation. The present results exhibit a strong influence of the bilayer period and Ta content on mechanical as well as thermal properties and consequently, on the age hardening, thermal stability and oxidation resistance of the Ti(1-x)Al(x)N/Ta(1-y)Al(y)N coatings investigated.

KW - oxidation resistance

KW - thermal stability

KW - protective coating

KW - TiAlN

KW - TaAlN

KW - age hardening

KW - Oxidationsbeständigkeit

KW - TiAlN

KW - TaAlN

KW - Hartstoffschichten

KW - Multilagenschichten

KW - Lichtbogenverdampfung

KW - Kathodenzerstäubung

M3 - Diploma Thesis

ER -