| WC films represent a class of materials with high strength and hardness, good chemical stability, high temperature, wear and corrosion resistance, and are regarded as"industrial teeth". So these materials have wide application prospect in engineering field, such as wearable coatings, the surface of cutting tools, dies and so on. Physical and Chemical vapor deposition techniques as conventional technology can be used to gain modified layer. However, the surface modified layer are easily destroyed, which is only limited increase for wear resistance and corrosion especially under the high temperature, high loading and sliding velocity condition.To solve these problems, this paper proposed to form WC ceramic layers on 20 steel with a special structure of source by using the double glow plasma surface alloying technique. The microstructure, composition and phase structure of the surface alloying layers are analyzed by means of OM, EDS, XRD and SEM respectively. The optimum process parameters of plasma WC ceramic layer on 20 steel are justified as follows: processing temperature(T) 1150℃, diffusing time(t) 4h, distance between source cathode and work-piece(d1/d2) 17mm/12mm, working pressure(P) 45Pa, source voltage(VS) 1000V, cathode voltage(VC) 300550V. The WC ceramic layers distribute gradually from the surface to substrate and metallurgically bond to the 20 steel substrate. XRD shows that the surface hardness of the ceramic specimen reaches 1188HV0.1. WC,W2C,FeW3C3 and W are the major phases of WC layer. Electrochemical tests indicate that corrosion resistance is enhanced in HCl solution, H2SO4 solution and NaCl solution, though with varied extent. Pin-on-Disc tests show that WC ceramic layer exhibit lower friction coefficient compared with untreated surface. The ceramic layer expressed good wear-resistance which is about more 4 to 6 times than the matrix at the home temperature and high temperature .
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