Microstructures of W-17%Co coating produced by plasma melt spraying(Ⅰ)

W-17% Co metallic ceramic coating was prepared by plasma melt spraying,(PMS) on low carbon steel Q235.Metallurgical bonded coating with high bonding strength had been obtained,and the key problem of low bonding strength for ceramic coating had been solved.Microstructures were analyzed with optical microscope,SEM,TEM and EDS.The results showed that a joint produced by PMS process was similar to a welded joint,and consisted of coating,fusion zone,diffusion zone,and heat affected zone.Microstructures of PMS coating are very different from the sprayed ones.Phases in the coating are very complicated and consisted mainly of M₆C,(Fe₃W₃C or Co₃W₃C),WC,γ-Fe,Co₃O₄,γ-Co,FeW₃C,Fe₂W and W₂C.These phases distribute in different regions in the coating.According to the microstructures,the coating can be divided into surface layer,metallurgical reaction layer and bottom layer.