Abstract: Roller bit is an important part of drilling equipment which is vulnerable to wear and corrosion. In order to extend the service life of the roller bit, the strengthen layer can be fabricated by laser cladding. In this paper, Ni60A coating and 5wt%,15wt%,25wt% WC reinforced Ni based coatings were prepared on 15CrNiMo steel by YLS-2000 laser instrument. Furthermore, the microstructure and element distribution of the coatings were analyzed by means of SEM and EDS. And the phase composition of each coating was investigated by XRD. Meanwhile, the electrochemical corrosion test was performed on a CHI660E type electrochemical workstation. The effect of WC content on the microstructure and corrosion resis-tance of Ni60A/WC cladding layer was studied, and the corrosion behavior of Ni60A/WC cladding layer and substrate in different pH corrosion solution was discussed. The results show that with the increase of WC content, micro area directional solidification appears in the coatings. In addition, the γ(Fe, Ni) and intermetallic compound of M23C6, M6C, et al are observed in Ni60A/WC layers. What's more, compared with the substrate, the corrosion current density of Ni60A/WC coating in different pH value corrosion solution is reduced by 1—2 orders of magnitude which perform good corrosion resistance, but its corrosion resistance is negatively related to the addition of WC. Besides, enrichment of H+ and OH- surroundings make the passivation film change from low valent oxide to superoxide.
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2021, Vol. 35 
