The corrosion resistance of cold sprayed Al-Zn-Al2O3 composite coatings

Al-Al(2)O3, Zn-Al2O3, Al-Zn-Al2O3 composite coatings were cold sprayed using low-pressure method, and their organizational structure and corrosion performance were studied. Al coating contains Al phase and alumina phase, Zn coating contains Zn phase and alumina phase, and Al-Zn composite coating contains Al, alumina and Zn phases. The coating and substrate are tightly bonded, no defects such as delamination or cracks in the coating are detected. The internal densities of the coatings are high, with good bonding between the particles and only a few small pores. Al coatings are corroded and then their surface alumina content increases. After corrosion, the products of Zn coatings are hydroxychlorinated Zn-5(OH)(8)Cl-2-H2O, ZnO and Zn(OH)(2). The products of Al-Zn composite coatings are mainly Zn-5(OH)(8)Cl-2 center dot H2O, ZnO, and Al2O3. Al-Zn composite coating formed more lamellate Zn-5(OH)(8)Cl-2 center dot H2O after corrosion, which reduced the coating corrosion rate and improved the coating corrosion resistance.