Effect of thermal annealing and deposition conditions on the structure and mechanical properties of a mulitlayer nitride coating based on Ta

Abstract

An analysis of the structure and mechanical properties of multilayer nitride coatings based on Ta depending on the deposition conditions and thermal vacuum-free annealing was conducted. Ta/TaN is a multylayer structure with alternate deposition of a polycrystalline layer of Ta of high ductility and a layer of TaN of high strength. TaN is a coating deposited by magnetron sputtering with the ratio N2/Ar = 0.4, exhibiting a high degree of crystallinity that leads to a high adhesive strength and hardness of Ta/TaN multilayer coatings. For nitride coatings based on refractory elements of the V–VI period, the general patterns consisting in the formation of the NaCl structure, and the predominant orientation of the planes (111) were identified. The application of heat treatment decreases the microhardness of the Ta/TaN multilayer coatings from 2600 to 1200 kgf/mm2, and leads to deterioration of the adhesive strength between the layers. In the process of mechanical testing, the tribological coefficient for the considered protective coatings was 0.1–0.25, the volume of surface wear was 14.3 mm3