Combined surface heat treatment: state-of-the-art

Thermal electron beam (EB) technologies, thermochemical surface treatments, and numerous variants of physical and chemical vapour deposition (PVD or CVD) hard coatings are used to treat a wide spectrum of different tools and highly loaded components, and have, to some extent, become successful industrial applications. Specifically, each of these groups of surface technologies is used to enhance surface hardness and wear resistance. The application is restricted, however, by physical, technical and technological characteristics. Special loading conditions present a great challenge, as the load–bearing capacity of each of the surface layers produced is limited. The combination of EB surface treatment with thermochemical treatment and/or PVD or CVD hard coating enables significant further improvement of the relevant properties. This paper presents a survey about the history, the state of the art of development as well as fields of application for these innovative duplex or triplex surface technologies.