Development of Fluoroethylene Propylene Coating Using Low Pressure Cold Spray

Cold spray is a powder deposition technique on a substrate, as a result of plastic deformation upon impact. In this study, fluoroethylene propylene (FEP) coating, a copolymer of tetrafluoroethylene and hexafluoropropylene, is successfully deposited on metal substrate using a low-pressure cold spray (LPCS) technique. This study describes the feasibility study of deposition behaviour of two different size distribution of FEP powder (17 μm and 100 μm) under several spray conditions. Firstly, FEP coating was seen to be influenced heavily by the gas temperature. The highest deposition efficiency was obtained when FEP was sprayed at a gas temperature of 500°C and gas pressure of 0.5 MPa. Secondly, FEP showed a better deposition tendency with lower particle size. Interestingly, the coating surface showed heavy shot blasting of the substrate surface possibly due to the increase in the stiffness of polymers at high strain rates, formed at high gas temperature by small sized powder, in contrast to 100μm powder, but also highly influenced by other spraying variables. SEM observation shows shot blasting effect on the substrate surface by the FEP particles.

Keywords: Low Pressure Cold Spray; Fluoroethylene propylene (FEP); Deposition efficiency; anti-wear coating.