This work describes the influence of standoff distance (SoD), and gas temperature on the morphology and corrosion resistance of Al-10%Al2O3 coatings deposited by cold gas spray (CGS) on carbon steel. The results showed that the standoff distance had little effect on the thickness and microstructure of the coating. However, a 100 °C decrease of the spraying temperature reduced the coating thickness by 300 µm. The use of electrochemical analyses and SEM images showed that all the coatings studied were able to protect the substrate during at least 1300 h of immersion, due to the dense microstructure obtained by CGS.

The corrosion of AA 7075-T6 aluminum alloy is a critical issue for many industries. In this study, aluminum coatings were deposited onto AA 7075-T6 by cold gas spray and the effect of the porous outer layer on different properties of the coating, including corrosion-resistance was investigated. As-prepared and polished samples were used to study the microstructure, morphology, mechanical properties and corrosion resistance of the coating in 3.5 wt.% NaCl solution. Cross-sectional analysis showed a dense structure, low porosity (0.8%) and thickness up to 300 lm (* 100 lm for the porous outer layer and * 200 lm for the compact inner layer). The sliding wear test resulted in a volume loss of 3.2 9 10 -4 mm 3 /Nm with an adhesive wear mechanism. The abrasive wear test showed a wear rate of 1.1 9 10 -4 mm 3 /Nm for the asprepared coating and 0.8 9 10 -4 mm 3 /Nm for the polished coating. The as-prepared coating pores and interparticle spacing in the outer layer were mostly responsible for the increase in wear rate. For the polished coating immersed in 3.5 wt.% NaCl solution during 900 h, the electrolyte reached some specific points of the substrate as revealed by the cross-sectional analysis. Inspection of the as-prepared coating demonstrated that the coating/substrate interface was completely damaged after long immersion times (* 900 h).