Developing rotary swaging process for improving the performance of wire-arc sprayed Al/Al2O3 composite coating

Wire-arc sprayed Al-based composite coatings attracted great attentions due to their prospective application in offshore engineering. However, the difficulty in regulating ceramic reinforcements limited the performance of these coatings. In this work, we proposed a novel rotary swaging (RS) process to improve the deposition of ceramic particles, thus the Al/Al2O3 composite coating was prepared and evaluated in comparison with the traditional coating by spraying the drawing cored wires. As expected, the RS process promotes the melt of Al2O3 particles, leading to a significant increase of their deposition fraction with the simultaneous improvement in coating compactness and the interfacial bonding of heterogeneous splats. The sufficient melt of Al2O3 particles is attributed to the enhanced cohesion strength of filled powders to bear the vibration of arc force and facilitate heat transport. The explored composite coating displays a superior corrosion resistance in 3.5 wt% NaCl aqueous solution, due to the reduced active area on electrode surface and the lower sensitivity to pitting. Benefiting from a dynamic self-reinforcing effect, the explored composite coating presents lower coefficient of friction and significantly enhanced wear resistance under dry frictional condition. The present results demonstrate a great potential of the developed Al/Al2O3 composite coating in offshore application and provide an inspiration for future works aiming to exploit the high-performance metal-matrix composite coatings synthesized by low-cost wire-arc spraying.