Tribological properties and oxidation resistance of (Cr,Al,Y)N and (Cr,Al,Si)N films synthesized by radio-frequency magnetron sputtering method

Quaternary (Cr,Al)N-based nitride was synthesized from alloy targets by the radio-frequency magnetron sputtering method. The mole fractions of (Cr,Al,Y)N were 44mol% CrN, 52mol% AlN and 4mol% YN, while those of (Cr,Al,Si)N was 49mol% CrN, 47mol% AlN, and 4mol% SiN. As-deposited (Cr,Al,Y)N and (Cr,Al,Si)N films had a cubic NaCl structure, and their average surface roughness Ra was approximately 8.1nm and 6.3nm, respectively. From thermogravimetric analyses, the weight of (Cr,Al,Y)N was observed to increase from 0.03mg/cm² to 0.30mg/cm² in the temperature range of 600°C-1000°C. In contrast, a linear increase in the mass gain of (Cr,Al,Si)N from 0.05mg/cm² to 0.18mg/cm² was observed up to a temperature of 1000°C. Structural changes from single-phase cubic (NaCl) to wurtzite (AlN) and Cr₂N occurred after thermal annealing in an ambient environment. During oxidation, metallic elements diffused toward the top surface, where the growth of oxides such as Cr₂O₃, Al₂O₃ and Y₂O₃ were confirmed. For the tribological test, the friction coefficient was below 0.6 under dry conditions at room temperature.