Observation of a Redeposition Effect while Cold Spraying Sn-based Mixed Powders onto Carbon Fibre Reinforced Polymers

Single component tin coatings have successfully been cold-sprayed onto carbon fibre reinforced polymers (CFRPs) in previous studies at McGill University. Coatings with mixed metal powders were also sprayed to improve the coating conductivity for lightning strike protection (LSP) purposes. Results indicated a noticeable improvement in deposition efficiency (DE) related to the addition of a secondary metallic powder (aluminum, copper and zinc); this study is focused on the effect of aluminum. Following cold spray of various Sn/Al mixtures over a wide range of gas pressures, unusual coating morphologies were observed. The study of these morphologies leads to the description of two distinct deposition phases depending on the spray pressure. The presence of submicron particles also supports the occurrence of a powder melting phenomenon during the process.