Microstructure, wear and corrosion behavior of cold-sprayed magnesium alloy coatings

摘要

AZ91D coatings were deposited by cold spraying using air as the accelerating gas at different temperatures to get the available main gas temperature. The results show that dense coatings can be fabricated until the gas temperature is above 500 °C. Coating porosity, cross-sectional microstructure, and phase structure were characterized. Porosity of AZ91D coatings remained between 3.6 and 3.9 %. X-ray diffraction and oxygen content analysis clarified that no phase transformation or oxidation occurred during cold spraying. Impact melting was found when the gas temperature increased to 550 °C. As-sprayed coatings exhibit higher microhardness than as-casted bulks. Wear performance was examined by measuring friction coefficient and wear rate, and wear mechanism was described by observing worn morphology. The wear mechanism of AZ91D coatings was adhesive wear. In order to increase wear resistance, AZ91D based composite coating reinforced with silicon carbide (SiC) particles were produced. Compared to AZ91D coating, the coefficient of friction of the composite coating is higher and the wear rate is lower, which can be attributed to the barrier effect due to the presence of SiC particles in the deposit. The wear mechanism of composite coating was abrasive wear. Wear resistance of composite coatings was enhanced; however, in the meantime, corrosion potential and corrosion current density increased.