Mixed-Material Feedstocks for Cold Spray Additive Manufacturing of Metal-Polymer Composites

High-performance polymers such as poly(ether ether ketone) (PEEK) are appealing for a wide variety of industrial and medical applications due to their excellent mechanical properties. However, these applications are often limited by relatively low thermal stability and conductivity compared to metals. Many methods developed to metalize polymers, including vapor deposition and thermal spray processes, can lead to poor quality control, low deposition rate, and high cost. Thus, cold spray is a promising potential alternative to rapidly and inexpensively produce polymer-metal composites. Furthermore, polymer-metal composite bond layers may serve to support the production of stronger, thicker, and more well-adhered metallic coatings.

In this study, we investigate the deposition characteristics of such initial bond layers, composed largely of PEEK with varying volume fractions of metal added, on a PEEK substrate. We approach the cold spray of the composite bond layer in two ways: by spraying a hand-mixed blend of the powders, and by preparing a PEEK-metal composite feedstock via cryogenic milling. We characterized these deposits by measurements of deposition efficiency, hardness, density, and porosity. Due to the larger volume fraction of PEEK in the feedstock, processing temperatures below those typically seen in PEEK metallization (300-500 °C) can achieve deposition.