Thermal stability and mechanical properties of arc evaporated Ti–Al–Zr–N hard coatings
| Autor: | Peter Polcik, R. Hollerweger, S.A. Glatz, J. Paulitsch, Paul H. Mayrhofer, Richard Rachbauer |
|---|---|
| Rok vydání: | 2015 |
| Předmět: |
Zirconium
Materials science Annealing (metallurgy) Metallurgy Oxide chemistry.chemical_element Surfaces and Interfaces General Chemistry Condensed Matter Physics Surfaces Coatings and Films chemistry.chemical_compound chemistry Materials Chemistry Thermal stability Crystallite Composite material Well-defined Oxidation resistance Wurtzite crystal structure |
| Zdroj: | Surface and Coatings Technology. 266:1-9 |
| ISSN: | 0257-8972 |
| Popis: | Based on previous reports, showing that zirconium alloying to Ti 1 − x Al x N hard coatings can increase their thermal stability, we study in detail the interaction of bias potential and Al content on structure, hardness, thermal stability, and oxidation resistance of arc evaporated Ti 1 − x − y Al x Zr y N hard coatings. For moderate Al-contents, Ti 0.49 Al 0.44 Zr 0.07 N, their structure is single-phase cubic and their hardness remains at ~ 35 GPa upon annealing in vacuum to 900 °C, when prepared with − 40 and − 80 V bias. Contrary, the coatings deposited with − 120 V bias experience already for annealing temperatures above 700 °C a hardness reduction from the as deposited value of ~ 40 GPa. The higher Al-containing Ti 0.39 Al 0.54 Zr 0.07 N coatings are mixed cubic and hexagonal wurtzite type structured, and with increasing bias potential the cubic phase fraction increases. Whereas the coatings prepared with − 120 V bias exhibit an almost constant hardness of ~ 25 GPa upon annealing to 900 °C, their counterparts prepared with lower bias, experience even a slight increase in hardness, due to the formation of well defined crystallites. However, only single-phased cubic structured Ti 0.49 Al 0.44 Zr 0.07 N coatings are able to withstand an oxidation treatment for 20 h in ambient air at 850 °C due to the formation of a dense, protective Al 2 O 3 based outer oxide scale. Their oxidation resistance decreases with increasing bias potential, due to the increased defect density and thus promoted diffusion. Based on our studies we can conclude, that although the droplet-size decreases and the as deposited hardness increases with increasing bias potential, their thermal stability and especially oxidation resistance decrease. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect