Polymer Cold Spray on Composite Substrates

acm7 Tracking Number 43

Cold Spray is an additive manufacturing technique that relies on heated and pressurized gas to accelerate small particles. This resulting kinetic energy transforms into plastic deformation strain through a quasi-adiabatic process, causing the particles and substrate to locally deform at their interface and adhere. Cold Spray has primarily been used for metal powder applications on varying substrates, but there are few studies on the use of polymer powders. This paper focuses on the deposition tests of different polymer powders on composite substrates, and their effects. PEEK, and PEI powders are sprayed on thermoplastic carbon fiber composites to determine if the powders deposit on the surface. The deposition is parameterized based on spray offset distance, gas temperature, and powder flow rate to determine the best parameters for bonding powder to a composite substrate. Deposition results are quantified through measuring the material added to or eroded from the substrate during the process. Cross-sectional microscopy analysis is conducted to characterize powder-substrate bonding effects. Results showed that both PEEK and PEI powder can produce deposition on composite substrates, and PEEK has the best deposition results at a gas temperature of 450 °C, with an offset of 20 mm. The best PEEK deposition parameters were used to attempt the repair of damaged thermoplastic composite substrates to restore their residual strength. Results show the Cold Spray composite repair has a lower ultimate strength restoration compared to traditional scarf repairs, however it can be used to produce a cosmetic finish.