Relationship between the mechanical properties and the microstructure of nanocomposite TiN/SiN1.3 coatings prepared by low temperature plasma enhanced chemical vapor deposition

Abstract Nanocomposite hard coatings were fabricated by PECVD from TiCl4/SiH4/N2/H2/Ar gas mixtures at substrate temperatures of 300 and 500 °C. The mechanical characteristics such as micro- and nanohardness, Young's modulus, toughness and stress were evaluated, respectively, by depth-sensing and classical indentations and by curvature method. The mechanical and tribological properties are systematically correlated with the film microstructure and composition determined by XRD, SEM, ERD-TOF, XPS and AFM. For optimized nanocomposite films consisting of approximately 8 nm size TiN grains incorporated in an amorphous SiN1.3 matrix, we found Young's modulus >270 and >350 GPa, hardness >25 and >40 GPa and compressive stresses ∼1.0 GPa and ∼2.5 GPa for low and high deposition temperatures, respectively. The effect of microstructure on the mechanical characteristics is discussed and the methodology of hardness measurements, in particular, the correlation between the depth-sensing indentation and the indentation size effect are addressed in detail.