Research on the multi environmental corrosion characteristics and mechanism of B4C doped Fe–Cr–Ni composite coating produced by laser cladding
Jing Liu, Zhepeng Song, Yongxin Wang, Kazuhito Nishimura, Jian Zhang, Xiaojiang Lu, Xuming Pang
Abstract
Different Fe-Cr-Ni composite coatings doped with B 4 C were produced on the surface of Cr12MoV steel by laser cladding. Special attention was paid to the effects of B 4 C content on the phase composition, microstructure, and corrosion resistance of the cladded layers. The results indicated that the Fe-Cr-Ni composite coating was primarily composed of α-(Fe, Cr) and γ-(Ni-Cr-Fe) solid-solution phases, as well as Fe 2 B, M 7 C 3 , Fe 3 Si and M 23 C 6 phases. Once the B 4 C content increased to 10 wt.%, the microstructure of the cladding layer became coarse and exhibited the prominent carbide agglomeration. The composite coatings with different B 4 C contents exhibited superior corrosion resistance compared to the pure substrate in both 3.5 wt.% NaCl and 1 mol/L HCl solutions. Furthermore, as the B 4 C content increased, the corrosion resistance of the coating initially increased and then declined. In particular, the Fe-Cr-Ni composite coating with an 8 wt.% B 4 C content experienced the pronounced passivation in the corrosive media and possessed the optimal corrosion resistance due to the synergistic effect of the passive film and carbide barrier layer.