TiSiCN and TiAlVSiCN nanocomposite coatings for wear and erosion protection

The main objective of this study is to compare the structure and properties of TiSiCN and Ti(AlV)SiCN coatings deposited by sputtering a Ti target and a Ti-6Al-4V target respectively, in an Ar+N₂+tramethylsilane (TMS) mixture using pulsed dc magnetron sputtering. The ultimate goal is to explore the possibility of using low cost commercial grade Ti-6Al-4V target material as a sputtering source of Ti for depositing Ti based nanocomposite coatings. In this study, the flow rate of TMS was varied from 0 to 4 sccm for each coating system. At the same TMS flow, the deposition rates for the Ti(AlV)SiCN coatings are higher than the TiSiCN coatings. Both coating systems exhibited nanocomposite structure, in which nanocrystallines were imbedded in a SiC_xN_y amorphous matrix. The mechanical properties and wear resistance of the coatings were analyzed using nanoindentation and ball-on-disk test, respectively. The TiAlVSiCN coatings showed improved hardness, H/E* ratio and wear resistance as compared to the TiSiCN coatings for a wide range of TMS flow rates. Finally, the erosion resistance of 30 mm thick optimized TiSiCN and TiAlVSiCN coatings were evaluated and compared with other thick hard coatings, e.g. CrN, CrAlN, CrN/AlN, etc., using air jet sand erosion tests.