FORMATION AND TRIBOLOGICAL APPLICATION OF CVD DIAMOND FILMS ON STEELS

It is well known that the mutual alloying effect of carbon and iron hi nders the direct coating of diamond films on steels. One of the promis ing ways to achieve direct coating of diamond film on tool steel is to interpose a buffer layer which impedes the interdiffusion of carbon a nd iron. This layer should be compatible both thermally and structural ly with the substrate material as well as the subsequent diamond film. Electroless plating was utilized to deposit a layer of nickel on the tool steel SKD 61. Subsequent deposition of molybdenum was conducted i n an electron beam evaporator. This bi-buffer layer of Mo/Ni deposited on SKD 61 served as a substrate for synthesizing diamond film in a lo w temperature (about 500-degrees-C), low pressure (about 5.3 KPa or 40 Torr) microwave plasma chemical vapour deposition system using hydroc arbons and hydrogen as reactant gases. The results showed that the adh esive strength was much improved through the application of a bi-buffe r layer, e.g. Mo/Ni or Mo/TiN.