Effect of accelerating gas temperature on microstructure and properties of cold sprayed Al coating on polyether ether ketone (PEEK)

Cold spray (CS) is an emerging deposition technique for the metallization of polymer material to improve its thermal and electrical properties. In this study, pure Al coatings were deposited on polyether ether ketone (PEEK) substrate by CS. Further, the influence of accelerating gas temperature on microstructure and properties (i.e. deposition efficiency, adhesive strength, electrical conductivity, thermal diffusivity and hardness distribution) of the prepared coatings was systematically investigated. Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), the quantitative analysis of oxygen content and Raman spectra results revealed that the prepared coatings were composed of crystalline metallic Al without obvious oxide phases. Moreover, the polymer structure of PEEK substrate remained intact after high-velocity and high-temperature impact during the CS process. The adhesive strength, electrical conductivity and thermal diffusivity of the Al coating increased with increasing accelerating gas temperature. At the accelerating gas temperature of 380 °C, a dense and thick Al coating with high adhesive strength was obtained in just two deposition passes. Moreover, multi-pass tests (at high nozzle traverse speed) were performed to understand the deposition mechanism of Al coating on PEEK substrate through analyzing cross-section/surface morphology of samples with different thicknesses. Finally, the deposition mechanism of cold sprayed Al coating on PEEK was proposed.