Effect of W Content on Microstructure and Corrosion-Wear Properties of W-Ni Coatings by Laser Cladding

Abstract

xW-Ni (x=60, 70, 80, 90 wt.%) coatings were prepared by laser cladding on the surface of X80 steel substrate to explore the effects of different W contents on the microstructure, corrosion resistance, microhardness and corrosion-wear properties of the W-Ni coatings. The results revealed that the microstructure of the various W-Ni coatings composed of W and γ (Ni, Fe) phases. The increase in W content resulted in more W atoms being dissolved in the γ (Ni, Fe) phase, enhancing the solid solution strengthening effect ,  which increased the average microhardness of the coating. Moreover, the addition of W provides diffusion channels for metal ions to migrate to the surface of the coating for passivation film formation, which improved the corrosion resistance of the coating. However, the addition of excessive amounts of W caused the coating density to decrease and accelerated galvanic corrosion. The 80W-Ni coating among the studied coatings exhibited excellent corrosive-wear resistance due to its high hardness and good corrosion resistance. This coating corrosive-wear mechanism was the combination of abrasive wear and corrosion.

Keywords: X80 substrate, laser cladding, W-Ni coatings, corrosion-wear resistance