Development of TiN-Si3N4 Nano Composite Coatings for Wear Resistance Applications

The engineering of conventional TiN coatings to attain hardness of the order of ultrahard coatings (e.g. c-BN) by a controlled incorporation of silicon atoms in the titanium nitride lattice leading to the formation of a TiN-Si 3 N 4 composite material is discussed. An a-priori thermodynamic approach complemented by thermochemical equilibrium calculations was used to evaluate convenient precursors and processing parameters for the production of this novel coating material. The multiphase nature of preliminary test samples deposited by PACVD is confirmed by X-ray diffraction, IR spectroscopy and EPMA analysis. The films are made up of TiN nanocrystallites embedded in an amorphous Si 3 N 4 tissue with small amounts of free Si, as predicted by previous Ti-Si-N phase diagram calculations.