Crystallization of Amorphous Metastable Ceramic PVD-Coatings

Ceramic PVD coatings have got very often an X-ray amorphous structure. This is regarded for all classes of ceramics like covalent and ionic materials. These amorphous materials start to crystallize at temperatures about 800 °C, a quite low temperature for the practical use of such materials. This prevents the propagation of this materials in applications like high temperature wear protection, oxidation resistivity etc. This paper describes several possible techniques to increase the thermal stability of the amorphous state of ceramic PVD-coatings like A1203 and SiC up to 1200 °C. The best way is the incoporation of an additional element like nitrogen into the thin filmsl. The change of the mechanical properties of alumina leads to new applications like diffusion barriers.