Comparative Research on Wear and Erosion Resistance of Ti–Al–Ni–N and Ti–Al–Ni–Mo–N Ion-Plasma Vacuum Arc Coatings

Comparative studies of resistance to various types of wear of nanostructured Ti–Al–Ni–N and Ti–Al–Ni–Mo–N coatings characterized by a homogeneous and multilayer architecture, respectively, were carried out. The impact of Mo and the architecture of coatings on the characteristics of resistance to wear and erosion of the studied ceramic–metal structures was estimated. It was found that neither coatings is characterized by a brittle failure mechanism. The increased fracture toughness of highly hard coatings of both compositions is governed by the presence of a plastic metal phase, a branched network of nanograin boundaries (Ti–Al–Ni–N), and a multilayer architecture (Ti–Al–Ni–N–Mo), which suppress crack growth. Both coatings showed high resistance to water erosion wear. The presence of molybdenum in the composition of the Ti–Al–Ni–Mo–N coating provides a decrease in the sliding friction coefficient at elevated temperatures due to the formation of an oxide phase (MoO3), which acts as a solid lubricant.