Materials Chemistry and Physics, Vol.208, 189-197, 2018
CrAlON CAE-PVD coatings for oxidation and wear protection of TZM alloys in FAST sintering applications
In this work CrAIO and CrAlO/CrAIN multilayers deposited by cathodic arc evaporation are evaluated as protective films in metal and ceramic powder FAST sintering tool dies fabricated in titanium-zirconium molybdenum allows (TZM). The films have been characterised in terms of their composition, microstructure, mechanical properties and thermal stability in air at high temperatures between 800 degrees C and 1100 degrees C; in addition the tribological performance has been analysed at room temperature and at 400 degrees C. The crystalline structure and composition of the CrAlO based coatings are compatible with the formation of a mixture of alpha-corundum and a cubic fcc (Cr,Al)(2)O-3. The crystalline structure of the multilayer is, on the other hand, dominated by the cubic fcc lattice plane reflections of the CrAIN. The deposited specimens have high hardness, between 25 and 30 GPa, which are stable even after annealing at 1000 degrees C. Even more, the multilayer coating also exhibited good mechanical stability at 1100 degrees C. The multilayer coating also exhibited an excellent behaviour against wear at 400 degrees C. Sintering trials using coated TZM dies have been carried out using Ti90Sn10 and Al2O3 high energy ball milled powders. The experimental results show that the oxide based coating formulations are potentially able to protect the tools from wear, sticking and oxidation of their surfaces. This may allow the use of TZM material as an alternative to other substrates such as graphite. (C) 2018 Elsevier B.V. All rights reserved.