Study on Process of Laser Cladding TiCNi Coating on Al Alloy by SHS Reaction
Based on the principle of the self-propagating high-temperature synthesis (SHS) reaction of Ti and C powders, a Ti CNi cermet composite coating was prepared successfully on LY12 alloy substrate by means of laser cladding. The good technical parameters such as laser power, scanning velocity, beam diameter, overlap ratio and so on were gotten. The OM, XRD, EDS techniques were employed to study the phases of the coating. The results show that the top coating is a layer of TiCNi, below which is the Ni-Al intermetallic fusion layer and the substrate, and the coating's microstructure is dense and pure. Elements are diffused mutually at both sides of the interface and a metallurgical bonding interface. The heating of the reaction coarsens the grain size of the substrate near the interface. The formation mechanism of the layer is explained. It involves a series of SHS reactions, including the reactions between Ti and Ni, Ti and C, Ni and Al. Good interfacial bonding is achieved at the fusion layer, TiCNi interface and the fusion layer/ LY12 alloy substrate. The thermal shock experiment was employed to study the thermal shock properties of the coating at different elevated temperature. The results show that the thermal shock property of the coating is fine.