CORROSION BEHAVIOR OF COLD SPRAYED ALUMINUM OXIDE REINFORCED ALUMINUM COATINGS

Abstract

The selection of materials in the cold spraying process has a significant impact in corrosion resistance. Recognition of this could provide the opportunity to adapt a wide range of coating deposits for different applications for repair in protection against corrosion. Cold sprayed coatings of pure aluminum and alumina reinforced aluminum were deposited to understand the role of composition on corrosion. Coatings were sprayed with thicknesses varying from 100 µm to ~3 mm in order to understand the role of coating thickness on corrosion. A salt fog chamber test helps mimic an austere marine condition for 1000 hours and 2000 hours of continuous exposure. Dimensional changes and mass gain were measured periodically throughout the salt fog exposure testing. The corrosion test revealed that reinforced aluminum is better for protection than pure aluminum having unresolved galvanic vulnerabilities within the coating and delaminating from the substrate. The alumina reinforced coating exhibited greater roughness in thicker coatings, which resulted in higher initial corrosion rates. With additional testing, cold spray could be used for coating protection of parts that are exposed to austere environments.