Effects of SiH4 flow rate on microstructure and mechanical properties of TiSiN nanocomposite coatings by cathodic arc ion plating

• TiSiN coatings were synthesized by arc ion plating using SiH4.
• TiSiN structure varied from columnar grain to nanocomposite.
• SiH4 flow rate significantly influences the microhardness.

TiSiN nanocomposite coatings were deposited on Si and cemented carbide substrates by cathodic arc ion plating in SiH4 ambient. The effects of SiH4 flow rate on microstructure, mechanical and tribological properties of the coatings were investigated systemically. Transmission electron microscopy and X-ray diffraction were employed to probe the crystalline microstructure and X-ray photoelectron spectroscopy was used to investigate the chemical bonding states. Microhardness testers and tribometer were used to evaluate the mechanical and tribological properties of TiSiN nanocomposite coatings. The results showed that the structure of TiSiN coating changed from columnar grain to nanocrystalline with increasing SiH4 flow rate. The hardness increased up to 4100 HV0.025 at the SiH4 flow rate of 42 sccm (9.5 at.% Si in the coating), but it decreases with further addition of SiH4 gases. Friction coefficients of TiSiN composite coatings in the range of 0.6–0.7 were obtained when tested against Si3N4 balls.