Microstructures and wear properties of laser cladding Co-based composite coatings on Ti–6Al–4V

Abstract

Abstract Metal matrix composite (MMC) coatings were fabricated on Ti–6Al–4V titanium alloy by laser cladding. Co42 self-fluxing powder, B 4 C, SiC and Y 2 O 3 were employed as the cladding materials. Microstructures and the wear properties of the different composite coatings were investigated comparatively. Results showed that the laser cladding coatings were mainly reinforced by CoTi, CoTi 2 , NiTi, TiC, TiB 2 , TiB, Cr 7 C 3 and Ti 5 Si 3 . The micro-hardness of the cladding coatings were equivalent to 3–4 times the Ti–6Al–4V substrate. Laser cladding coating exhibiting outstanding wear resistance was fabricated with the addition of 20 wt.% B 4 C, 7 wt.% SiC and 1 wt.% Y 2 O 3 . The wear resistance was enhanced by over 10 times compared with the substrate. However, with more SiC addition (14 wt.%), a higher micro-hardness was obtained together with poor wear resistance. The wear mechanism of the coatings was discussed by referring to the microstructures and the wear morphologies.