Comparison of crack resistance between ternary CrSiC and quaternary CrSiCN coatings via nanoindentation

Quaternary CrSiCN and ternary CrSiC coatings with various Si concentrations were synthesized on Si(100) wafers via adjusting the flow of (CH3)3SiH (TMS) in precursor gases. The mechanical property and crack resistance of these coatings were evaluated and compared, as well as the influence of Si concentration was investigated. Compared with the CrSiC coatings, the CrSiCN coatings had higher elasticity and compressive stresses, and in turn, exhibited higher resistance to radial cracks in despite of the Si concentration. The greater thickness of CrSiCN coatings is, the better the crack resistance is. By increasing Si concentration, the compressive stress was released in both categories of coatings, but the trends of crack generation for the two categories of coatings were totally different. For the CrSiCN coatings, a reduction of compressive stress prevented parallel crack initiation around the impression edge after unloading. In contrast, as the compressive stress in the CrSiC coatings was released, radial cracks were generated at the impression corners and the length of radial crack increases with the stress release.