Investigation of the Effect of the Plasma Thin-Film Coating System Si−O−C−N on the Surface Hardening of High-Speed Steel

Abstract

The results of studying changes in the strength properties of the surface of a tool product from high-speed steel (HSS) of the W6Mo5Cr4V2 type after its hardening by the application of the Si−O−C−N micron plasma coating system are presented. The study is conducted by comparing the properties of the surface, evaluated by the same methods before and after coating. In this case, the sample goes through a complete cycle of mechanical and heat treatment designed for the product before coating. The results of evaluation of the adhesive strength of the coating using the proposed method of recalculation are given, and the correspondence between the index of destruction of the coating of the VDI 3198: 1992-08 technique and the delamination coefficient is obtained. The study itself is carried out by indenting and scratching the surface with HV, HRC and HRB-type indenters in the load variation range of 0.1–200 N, which makes it possible to simulate different levels of contact pressure in the surface layer of the substrate and at the base–coating interface. It is shown that the application of a thin-film coating of the Si−O−C−N system by the plasma method makes it possible, in addition to standard heat treatment of HSS steel, to increase the surface resistance to penetration and scratching with harder bodies. The causes of the obtained positive effect are analyzed and the limits of the expediency of applying plasma hardening depending on the contact task are described. These results make it possible to consider the method of the additional plasma hardening of HSS steel as promising for implementation.