Surface Microstructure and Anti-wear of WC-CoCr Coatings Cladded by Electron Beam

Abstract

Nickel based alloy has good corrosion resistance in chloride medium, but its wear resistance is insufficient. In this paper, WC-CoCr coatings were deposited on Inconel617 alloy surface by HVOF (high velocity oxygen fuel). Electron beam remelting process was explored to modify the morphology and the phase composition of the coated layer. The results show that some structural defects of the as-sprayed coating are improved after electron beam treatment. Tribological tests concerning the sliding wear behavior of the tested materials reveal a significant decrease in the wear rate for the alloyed surface in comparison with the base material. After high energy electron beam treatment, the micro-hardness (HV_0.3) of the surface is 11000 MPa which is about 2 times as much as that of the matrix (5500 MPa) due to the formation of new phase (especially the Co₆W₆C phase) with high hardness. Besides the amount of porosity of the coatings is reduced and the grain is refined. EDS spectrum analysis indicates that new elements occur in the proliferation of cladding layer and the substrate achieves a good metallurgical bonding with the coating. Moreover, the corrosion resistance of the cladding layer in salt water is higher than that of the matrix.