Chemical Vapor Deposition of Titanium Nitride based Hard Coatings
Research output: Thesis › Doctoral Thesis
The deposition of TiN by thermal chemical vapor deposition (CVD) is well-established in cutting tool industry due to the balanced combination of hardness, oxidation resistance and adhesion. In this work, the coating properties of titanium nitride were examined and, moreover, systematically altered by the addition of C, B, or Al to form either single-phase Ti(C,N) coatings, dual-phase coatings within the ternary system Ti-N-B, or metastable coatings in the Ti-Al-N system. It has been shown that the mechanical, thermal and, ultimately the tribological properties can be modified over a wide range by adjustment of the process conditions and the addition of different alloying elements. The high impact of the deposition temperature on the microstructure was shown for coatings of pure TiN. Fine-grained textured structures provide a high toughness and an enhanced wear resistance. The properties can be adjusted from super-hard Ti-N-B coatings by a high-phase fraction of TiB2 to low friction coatings of Ti(C,N). It has been proven for the first time that the deposition of metastable TiAlN coatings is feasible by thermal CVD on an industrial scale. The results provide a basis for further developments with regard to commercial fcc-(Ti,Al)N coatings.