HVOF Spray Performance Optimization Analysis and Experimental Research of WC–12Co Coating on Ti Alloy

TC18 titanium alloy, with low density, high strength and corrosion resistance, is a significant material for the main load-bearing components of aircraft landing gear and other aviation structures. However, its corrosion resistance and wear resistance are insufficient when it is serviced in the extreme corrosion environments such as sea salt spray and hygrothermal, which greatly affects its wide application. It is significant to design and develop high-quality anti-corrosion and wear resistant coatings for TC18 titanium alloy. High Velocity Oxygen Fuel (HVOF) spraying WC–12Co is an ideal strengthening method to replace surface chromium plating. Quantitatively evaluating the influence of spraying process parameters on the coating quality is the key to prepare high-quality coatings. In this study, a numerical model of HVOF spraying WC–12Co was established with JP5000 spray gun. The spray combustion reaction model and discrete phase model were solved to reveal the evolution characteristics of combustion flame flow and particle flight behavior in the spraying process. Based on the response surface method, the optimum spraying process parameters were determined, and the WC–12Co coatings were prepared. On this basis, the coating was tested by the SEM, XRD, hardness, friction and wear, salt spray corrosion and seawater corrosion. The corrosion resistance and wear resistance of the WC–12Co coating were comprehensively evaluated. The experiment shows that the WC–12Co coating prepared by HVOF spraying has great performance, which can effectively improve the protective performance of TC18 substrate.