Effect of Pressure and Temperature on the Microstructure and Mechanical Properties of SiCp/6061Al Coating Using High-Pressure Cold Spray

The SiCp/Al composite coating was prepared by cold spraying technology to avoid the formation of brittle compound Al₄C₃ at low temperature. Plastic aluminum alloy particles and brittle SiC particles interact during cold spraying to promote the formation of defect-free structures through local mechanical interlocking and metallurgical bonding. In this work, high-pressure cold spraying technology was utilized to apply 18 wt.% SiCp/6061Al composite powders onto a 6061Al substrate. The cold spray parameters of temperature and pressure were investigated to improve particle fragmentation induced by high speed. Nano-hardness testing was employed to reveal local plastic distribution for describing particle fragmentation behaviors. In the process of high-speed impact, plastic 6061 Al particles will increase the mutual binding between particles and lead to the increase of the compactness of the coating, while brittle particles will produce cracks decreasing the quality of the coating. Optimal conditions were identified at a gas temperature of 650 °C and a gas pressure of 4 MPa, resulting in the minimum SiC particle breakage within the composite coating has a peak shear strength of 101.2 MPa. A correlation between gas temperature and pressure with particle fragmentation was established, offering insights into the particle breakage concern during the cold spraying process for composite material coatings.