Si-target power dependence on the microstructure, mechanical behavior, and electro-optical characteristics of magnetron sputtered Six(TiZrHf)1-xN coatings

Si-doped (TiZrHf)N was cosputtered from TiZrHf and Si targets on Si substrates in N2/Ar atmosphere. The effect of Si-target power on crystal, microstructural, mechanical, and electro-optical characteristics was examined. The Si content raised to 8.74 at.% significantly with increased Si target power to 70 W. The Si-free coatings had a V-shaped columnar structure with voided boundaries and a (111)-preferred direction. With increased Si-target power, the grain size and residual compressive stress initially increased and then decreased. The microstructure of the coatings obviously became compact and eventually transformed into a nanofibrous structure with (200) preferred orientation. When the Si-target power rised up to 50 W, the Si content reached 2.60 at.% and the coating demonstrated a maximum hardness of 34.8 GPa. The electro-optical properties of coatings greatly deteriorated with Si content regardless of structural evolution. The electrical resistivity of the coatings increased from 52 μΩ cm to 6250 μΩ cm, and their light reflectivity at 0.62 eV dropped from 83.5% to 33.6%.