Metallization of polymers by cold spraying with low melting point powders

Abstract

Polymers and polymer composites have been increasingly used due to their low density and high specific strength; however, their low electrical conductivity has limited their further application. Cold spray has recently been proven to be a feasible approach to metallize polymers. Previous results have shown that tin can be cold sprayed onto polymeric substrates when spraying with a low-pressure cold spray system at gas temperatures close to the melting point of tin. The successful deposition of tin was partly attributed to the tin reaching its incipient melting point. In this work, three low melting point metal powders, namely, Sn, Sn-Zn alloy, and Sn-Bi alloy, were cold sprayed onto five widely used engineering polymers . Different combinations of gas temperature and gas pressure were assessed. Results show that decreasing the melting points of the feedstock powders can improve their deposition efficiency on polymeric substrates, due to a higher degree of particle melting. Among the five polymers, the high-toughness ultra high molecular weight polyethylene and polycarbonate were relatively difficult to metallize. • SnZn and SnBi powders with lower melting points than Sn were cold sprayed on polymeric substrates. • Five common engineering thermoplastic polymers (ABS, Nylon, PC, PE, and PP) were metallized using low melting point powders. • Particle melting facilitated the deposition and inter-particle bonding, resulting in high deposition efficiency. • SnBi coatings exhibit higher adhesion to ABS than Sn when spraying at 300°C and 60 psi.