Laser Cladding of Metal-Ceramic Composites

Abstract

AbstractMetal-ceramic composite coatings are often applied on metal surface to enhance wear and corrosion resistance. Laser cladding, owing to metallurgical reaction occurring in the laser process, creates better interface bonding of the coating than other deposition techniques such as plasma spray, cold spray, high-velocity oxygen-fuel (HVOF), and slurry sintering, which form the interface bonding mainly by diffusion or mechanical interlocking. In this chapter, the studies of WC/NiCrMo composite coating and TiC/H13 steel composite coating via laser cladding are presented. WC-NiCrMo powder was pre-alloyed, and then, it was cladded on SS316L using circular and wide-band laser spot, respectively, and TiC/H13 composite powder is deposited on H13 steel with circular laser spot. Optical microscope (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS) were used to observe the microstructure and distribution of the reinforcement particle. Dry sliding wear test was used to study the wear behavior of the coatings. The results show that the WC particles which were partially dissolved were uniformly distributed in the two coatings. The coatings mainly contain WC, M23C6 carbides, and γ-(Ni, Fe) solid solution matrix. The different hardness and wear resistance of the two coatings result from the different microstructure, which are caused by the different dilution of Fe. The property of the coating produced by wide-band spot laser presents better than the coating produced by the circular spot laser. The microstructure of the TiC/H13 coating is not uniform because of the temperature gradient of the coating during the laser cladding process. The thermal stability of the TiC/H13 coating is investigated by examining the hardness change at the high temperature of 873 K.