Influence of Si content on Nano-structured Ti–Si–N films coated by pulsed-d.c. plasma enhanced CVD

Multiphase nanocomposite thin films composed of nanocrystalline TiN, nano-sized amorphous Si3N4, free silicon, and occasionally amorphous or nanocrystalline TiSi2, were deposited on HSS substrate at 550 °C using an industrial set-up of pulsed-d.c. plasma enhanced chemical vapor deposition technique. The composition of the films could be controlled well through adjustment of N2 flow rate and the mixing ratio of the chlorides. The Si contents in the films varied in a range of 0–40 at.%. The microhardness of the coatings increased firstly with increasing Si content, reached a maximum value of about Hv 5700 at the content of 13 at.% Si in the coatings, and then decreased at high Si contents.