Effects of ceramic particle size on microstructure and the corrosion behavior of cold sprayed SiCp/Al 5056 composite coatings

An Al 5056 alloy coating and Al 5056 based composite coatings reinforced with silicon carbide (SiC) particles were produced by cold spray technology. The microstructure was observed by different methods, from the coating surface through the cross sections to the interface. Attention was paid to key parameters governing the corrosion resistance of coatings: porosity, surface roughness, interface morphology and distribution of ceramic particles. The addition of SiC particles resulted in denser coating, homogeneous distribution of reinforcement phase and modified coating surface roughness and interface morphology. Corrosion behavior was studied by electrochemical measurements and corrosion resistance was also tested by long-term immersion. Results showed that the cold sprayed Al 5056 coating and SiCp/Al 5056 composite coatings provided cathodic protection for an aluminum substrate. SiCp/Al 5056 composite coatings showed better corrosion resistance than Al 5056 coating. Greater spraying efficiency and the best corrosion resistance were obtained with SiCp particles size close to 20 μm.