Component repair using HVOF thermal spraying

Abstract The high velocity oxy-fuel (HVOF) thermal spraying technique has been widely adopted in many industries due to its flexibility and cost effectiveness. It is normally used to apply coatings to components to protect against wear, heat and/or corrosion, but also has potential to build up worn components. The main objective of this study was to optimise the HVOF spraying technique for the repair of damaged tool steel (D2) and stainless steel components. Experimental work presented involved the spraying of repair material on specimens in which `defects' had been introduced. These defects were grooves of various depths machined in the samples. Each sample was then sprayed with the repair material until the whole face of the sample was covered with the deposited material. Depth of groove and spraying parameters were varied. The machinability of each repaired component was examined. Techniques used include milling, grinding, turning and spark erosion. Metallography is used to evaluate the quality of adhesion of repair material both prior and subsequent to machining, and trends based on processing parameters are identified.