Plasma sprayed aluminium nitride (AlN) coating: Microstructural, mechanical, tribological, and corrosion resistance performance

In this work, oxide-free AlN coating was fabricated using single-step, large throughput nitrogen-shrouded plasma spraying. Initially, Al/AlN composite feedstock powder was prepared by a ball-milling at a 70:30 wt% ratio to deposit the AlN coating. Microstructural evaluation revealed the formation of dominant c-AlN phase along with minor h-AlN without presence of any oxides or impurities in the coating. Hardness and elastic modulus (E) were observed to be -7.2 GPa and -280 GPa respectively. Furthermore, an investigation of tribological performance showed the wear rate -0.18 x 10-3 mm3/Nm and coefficient of friction (COF) 0.45 +/- 0.02. In addition, the corrosion resistance behaviour of AlN coating in 3.5 wt% NaCl shows as low as 2.95 x 10-9 mm/s indicates the extended life of the coated components. Therefore, the fabricated plasma-sprayed AlN coating can be recommended for high-performing wear and anti-corrosive competitor for industrial applications.