Wear Behavior of Plasma-Sprayed Carbon Nanotube-Reinforced Aluminum Oxide Coating in Marine and High-Temperature Environments

Wear behavior of plasma-sprayed carbon nanotube (CNT)-reinforced aluminum oxide (Al2O3) composite coatings are investigated at room temperature (298 K), elevated temperature (873 K), and in sea water. Lowest wear volume loss was observed in the sea water as compared to dry sliding at 298 and 873 K. Relative improvement in the wear resistance of Al2O3-8 wt.% CNT coating compared to Al2O3 was 72% at 298 K, 76% at 873 K, and 66% in sea water. The improvement in the wear resistance of Al2O3-CNT coatings is attributed to (i) larger area coverage by protective film on the wear surface at room temperature and in sea water, (ii) higher fracture toughness of Al2O3-CNT coatings due to CNT bridging between splats, and (iii) anti-friction effect of sea water. The average coefficient of friction (COF) was the lowest (0.55) in sea water and the highest (0.83) at 873 K for Al2O3-8 wt.% CNT coating.