A Novel Al-Al<sub>2</sub>O<sub>3</sub> Non-Skid Composite Coating with Improved Wear Resistance Fabricated by Twin Wire Arc Spraying

Abstract

In this study, novel non-skid Al-Al<sub>2</sub>O<sub>3</sub> coatings with improved wear resistance were fabricated using twin wire arc spray (TWAS). TWAS Al coating was prepared as a reference sample and representative TWAS parameters (working distance, process gas pressure, arc current) were controlled to fabricate different Al-Al<sub>2</sub>O<sub>3</sub> coatings. The Al-Al<sub>2</sub>O<sub>3</sub> coatings showed a superior static coefficient of friction and higher surface roughness than the Al coating. The microstructural analysis of the Al-Al<sub>2</sub>O<sub>3</sub> coatings revealed that the coatings contained Al splats, partially-melted Al<sub>2</sub>O<sub>3</sub> particles, fully-melted Al<sub>2</sub>O<sub>3</sub> splats and pores. The porosity and Al<sub>2</sub>O<sub>3</sub> content of the Al-Al<sub>2</sub>O<sub>3</sub> coatings varied with different process parameters. The Vickers hardness of the Al matrix showed a similar value in all samples, which means the deposition phenomena was the same. Ball-on-disc wear test with a Si3N4 ball was used to evaluate the wear resistance of the TWAS coatings. The weight loss of the Al-Al<sub>2</sub>O<sub>3</sub> coatings were only 4.8 ~ 17.0 % of the Al coating, indicating that the wear resistance of the TWAS Al-Al<sub>2</sub>O<sub>3</sub> coatings was superior. The TWAS coatings showed a complex wear mechanism, such as splat wear and abrasive wear. The distributed Al<sub>2</sub>O<sub>3</sub> particles in Al-Al<sub>2</sub>O<sub>3</sub> coating successfully suppressed the abrasive wear of the Al matrix, which contributed to the enhanced wear resistance. The results in this study indicated that the Al-Al<sub>2</sub>O<sub>3</sub> composite coating has potential use as a novel non-skid coating.