At present, the research on low - pressure cold sprayed Al - Al2O3 composite coating mainly focused on the process and properties, and there was less research on the deposition characteristics and mechanism of particles. For this, the Al - Al2O3 composite coating was deposited by low pressure cold spraying technology (LPCS). The effects of different carrier gas temperatures on the deposition characteristics of the composite coating were studied. The thickness, surface morphology and microstructure of the composite coating were analyzed by scanning electron microscope (SEM) and three - dimensional profiler. Results showed that the thicknesses of Al - Al2O3 composite coating prepared by LPCS at different carrier gas temperatures (300, 400, 500 and 600 ℃) were 213.34, 321.62, 920.64, 986.97 μm, respectively. The thickness of composite coating increased with the increase of carrier gas temperature. Especially when the carrier gas temperature of cold spraying increased from 400 ℃ to 500 ℃, the thickness of deposited coating was increases by 186.25%. The maximum height difference Hmax and roughness Ra of the composite coating surface increased with the increase of carrier gas temperature. When the carrier gas temperature was 400 ℃, the surface quality of the composite coating was the best. When the carrier gas temperature rose from 400 ℃ to 500 ℃, the increased amplitudes of Hmax and Ra were the largest, 72.68% and 52.22%, respectively. The surface quality of the composite coating decreased with the increase of carrier gas temperature. The flattening rate of deformed Al particles in the composite coating decreased with the increase of carrier gas temperature. Al particles in the composite coating gradually changed from flat shape with large plastic deformation (300 ℃) to ellipsoid shape with small plastic deformation (600 ℃). The sudden increase of deposition rate of Al - Al2O3 coating and the decrease of particle flattening rate with the increase of carrier gas temperature were attributed to thermal softening effect of Al particles.
