Influence of powder heat treatment and particle size on the corrosion performance of cold-sprayed nickel-aluminum bronze (NAB) for repair applications

Nickel-Aluminum-Bronze powder was heat-treated to reduce martensite and segregated into three sizes for Cold Spray deposition. Heat treatment (HT) significantly increased deposition efficiency (DE) from 20 % to nearly 100 %. Mechanical properties (hardness, scratch) and electrochemical corrosion tests were conducted to evaluate inter-splat bonding. Performance tests revealed that as-received (AR) powder deposit exhibited superior properties, albeit with a low DE. Among HT powders, the coarser size exhibited better inter-splat bonding due to particle size and surface oxide of the powder. The AR powder's enhanced performance is linked to a novel densification mechanism.