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In this study, the low-cost and high-wear-resistant iron-based surfacing alloy powder is used to prepare composite coatings on the 2 mm thick Al7075 substrate with different volume ratios of Al6061 powder (3:4, 5:4 and 2:1) by the low pressure cold spray equipment. The thickness of composite coatings increases with the increasing in preheating temperature and is approximately 60-80 μm thick in single pass. The percentage of iron-based surfacing alloy powder increased with the decrease in the proportion of Al6061 powder. The microhardness and bonding strength of the coatings increase with the increase in the percentage of surfacing alloy powder due to the tamping and work-hardening effect. The wear mechanism of cold sprayed composite coatings involves both abrasive and adhesive wear on the worn surface under different loads. The wear mechanism of the micro-arc oxidation sample transforms via abrasive wear to abrasive and adhesive wear as the load changes from 5 to 10 N. Investigation about wear properties reveals that the micro-arc sample has better wear resistance at the load of 5 N, but the cold sprayed composite coatings have better wear resistance at 10 N. The Al2O3 layer is worn out and the substrate is exposed during sliding for micro-arc oxidation samples at the higher load. The results indicate that the low pressure cold spraying may replace the micro-arc oxidation technique under the higher load condition in industrial applications. [ABSTRACT FROM AUTHOR]

Three types of aluminum alloy powder were mixed with the Al-based metallic glasses powder in different proportions, and the Al-based metallic glasses composites were prepared by cold spraying. The microstructure of the coatings was investigated, and the compressive strength of the Al-based metallic glasses composites was tested. Numerical simulation was carried out to study the formation of the composite coatings. The porosity of the composite coatings was significantly lower than for the Al-based metallic glasses coating. The maximum compression strength was 584 MPa when adding 50% Al7075 powder, and the compressive strength of Al-based metallic glasses composites has a positive correlation with the types of added aluminum alloy powder. The grinding effect due to the relative slip between the Al-based metallic glasses particles and the soft particles was observed at the fracture surface. The Al-based metallic glasses particles were packed closely with the surrounding Al7075 particles after fracture. Simulation results showed that the soft particles behaved like a droplet when impacted onto the metallic glasses particles, and gaps between the metallic glasses particles were filled with soft particles, but some pores still existed when adding Al7075 powder due to its relatively higher strength. [ABSTRACT FROM AUTHOR]