Application criteria of CuAlNi shape memory coatings under sliding friction conditions

The article examines the criteria for the application of CuAlNi ion-plasma coatings with the shape memory effect under sliding friction conditions in order to ensure the reliable and safe operation of friction units in transport systems, machines, and mechanisms. The relevance of developing functional coatings capable of improving the reliability and durability of friction units in transport systems, machines, and mechanisms is demonstrated. The aim of the study is to investigate the influence of vacuum PVD technology on the manifestation of the shape memory effect in CuAlNi coatings and to evaluate their tribological properties. The composition, microstructure, mechanical characteristics, and tribological behavior of coatings produced by ion-plasma synthesis were studied. It was established that the resulting coatings are characterized by a homogeneous structure, strong adhesion to the substrate, and satisfactory surface quality. Indentation results revealed signs of strain recovery, indicating the preservation of the shape memory effect in micrometer-thick coatings. It was shown that CuAlNi coatings exhibit a low coefficient of friction comparable to that of some highly efficient protective coatings. At the same time, it was found that under the investigated loading conditions, the realized shape memory effect is insufficient to provide a significant reduction in wear intensity. It is substantiated that the higher efficiency of such coatings may be achieved under lower loads and higher sliding speeds accompanied by an increase in the contact-zone temperature. The obtained results are of interest for the development of a new generation of wear-resistant coatings intended for medium-loaded and high-speed tribological contacts.