Study of Microstructure and Properties of Laser Cladding Ni60-WC + TiC Composite Coating

Abstract

As a novel surface strengthen technology laser cladding was widely used in surface engineering. In this work, Ni60 + 25%WC + 10%TiC composite coatings were fabricated on the TC4 by laser cladding technology. Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and frictional wear were used in the study of coatings. The results showed that dendrites is the main crystal type in the coatings, there were some bulk type crystal generated in 400 mm/min scanning speed. XRD results showed that some of the metalloceramics phases, such as TiC, VC, WC were formed in the coatings, some of the intermetallic compounds such as AlNi3, Al0.96B0.04Ni3, NiTi and C0.12Fe1.88 also formed, which improving the hardness, and the hardness tests results showed that the hardness of the coatings increased by 300% compared to the substrate, of above 1100 HV0.3. The max friction coefficient in 600 mm/min was 0.39, because of the unmelted TiC and WC particles fallen off from coatings, so the mechanism of the coating was abrasive wear. The friction coefficient is decreased to 0.11 and 0.19 when the scanning speed is 500 mm/min and 400 mm/min, respectively.