Effect of SiC Deposition Behavior on Microstructure and Mechanical Properties of Cold-Sprayed Al5056/SiC Composite Coatings

To study the effect of deposition behavior of the reinforcement on microstructure and property of cold-sprayed metal matrix composite coating, four Al5056 composite powders containing 15 wt.%, 30 wt.%, 45 wt.% and 60 wt.% SiC were mixed to prepare the composite coatings by cold spraying. Effect of the SiC deposition behavior on microstructure, SiC distribution, micro-/nanohardness, surface residual stress and shear strength of the coatings were studied. Experimental results show that the increase in SiC content in the powder increased the SiC collision with the deposited SiC particles, which caused the difference in SiC content and distribution in the composite coatings. The SiC deposition behavior caused the SiC morphology to evolve from integrity to small cracks and complete fragmentation. The SiC deposition behavior effectively influenced its peening effect on the deformed Al5056 particles, that is, as the SiC fragmentation threshold arrived, the nanohardness, surface residual stress and shear strength of the coating showed the corresponding transition point. The surface residual stress state of the deformed Al5056 matrix could in turn affect the SiC deposition by increasing the SiC deposition efficiency at the minimum compressive stress.