Effects of B content on wear and corrosion resistance of laser-cladded Co-based alloy coatings

To improve the surface properties of Ti alloy, (Co₃₄Fe₈Cr₂₉Ni₈Si₇)_100–x B_x alloy, coatings were prepared by laser cladding. The coatings—mainly composed of TiCr, Fe_0.1Ti_0.18V_0.72, CoTi, Ti₂Ni, and TiB—and amorphous phases were investigated in terms of microstructure, wear resistance, and corrosion resistance. The results showed that the microhardness of the Co-based coatings first increased and then decreased with the increase of B content. When the B content was 6%, the microhardness of the coating increased up to 1210 HV_0.2 which was 3.4 times that of TC4 alloy substrate. The coatings exhibited diverse wear mechanisms that gradually transitioned from severe fatigue spalling and oxidative wear to slightly abrasive wear. The corrosion current density of Co-based coatings in 3.5 wt% NaCl solution first increased and then decreased as B contents increased. Coatings with 4% B content, however, exhibited the best corrosion resistance, which was most suitable for improving the corrosion resistance of Ti alloy.