Physicomechanical properties of coatings based on MAX phases of Ti2AlC and (Ti, Nb)2AlC at 20ºС and 500ºС

Physicomechanical characteristics of 15Kh16k5N2MVFAB-Sh steel (0.15C–16Cr–5Co–2Ni–0.7V–0.6Mo–0.3Nb–0.4N): wear resistance at 20°C and 500°C and resistance to fretting fatigue at 20°C without and with coatings obtained by the method of vacuum-arc deposition using targets based on the MAX phases of Ti2AlC and (Ti1−𝑥Nb𝑥)2AlC, where x = 0.1 and 0.2, are investigated. At 20°C the friction coefficient and the wear specific rate of all coatings are greater than that of the studied steel in contact with a ShKh15 steel (1.0C–1.5Cr–0.3Ni–0.3Mn–0.3Si–0.25Cu) ball under a load of 2 N. Unambiguous relationship between microhardness and tribological characteristics of materials has not been recorded. The resistance to fretting fatigue of the samples with Ti2AlC -based coating in contact with the Ni-alloy (17Cr–12W–11Fe–6Co–3Ti–1.5Nb–1.6Al) in high-cycle region (N > 105 cycles) is significantly higher than that of uncoated samples. The tribological characteristics of all materials decrease at 500°C but the least for samples with Ti2AlC based coating. We have not found positive influence of niobium doping on the wear and fretting fatigue resistance of these coatings.