Microstructure and properties of in-situ chromium carbide composite coating by laser cladding

Using Ni/Cr/graphite powder blends as raw powders, a Ni matrix composite coating reinforced by in-situ carbide, was fabricated on the surface of Q235 by means of laser cladding. These microstructure and properties were discussed. The result of phase analysis (XRD) and microstructure investigation (SEM) showed that the coatings consist mainly of Cr3C2, Cr7C3 and γ-(Ni, Cr), which are consistent with the thermodynamic calculations. The wear morphology of the coatings was also examined. The results of dry sliding wear tests of different Cr/C ratio show that the wear resistances of the Cr3C2-reinforced coating, respectively, are 13.4, 9.5, 9.1 and 6.5 times higher than that of the substrate and the main wear mechanisms of the coatings are adhesion and abrasive wear with slight oxidation.