TiAlOn black decorative coatings deposited by magnetron sputtering

Abstract Black decorative coatings with improved mechanical properties (wear resistance) were deposited from TiAlON source material. A composite ceramic Al 2 O 3 + 1.5TiN has been used as a target in a planar magnetron rf sputtering system (13.56 MHz, 1200 W). A non-reactive process at high argon pressure yielded black, shiny coatings with deposition rates above 0.5 μm h −1 . In this study we report on the structural analyses as well as on the high temperature stability of such coatings. Transmission electron microscopy studies on very thin films (50 nm) have given evidence of a two-phase microstructure: crystallized grains of average size 10 nm are embedded in an amorphous matrix. X-ray diffraction has shown that these grains had the cubic B1 structure of TiN, with a lattice constant of 0.413 nm for as-sputtered films. Post-deposition thermal treatment under vacuum up to 900°C for 5 h affected only the lattice parameter which decreased to 0.409 nm. At 1000°C, the amorphous matrix decomposed into two crystalline phase: α-Al 2 O 3 and TiO 2 (rutile). The present investigation has shown that stable black decorative coatings can be deposited by a simple PVD process from a single target.