A Comparison Study of the Friction and Wear Behavior of Nanostructured Al₂O₃-YSZ Composite Coatings With and Without Nano-MoS₂

In this paper, nanostructured Al₂O₃-40%YSZ (AZ) and nano-MoS₂/Al₂O₃–40%YSZ (AZM) powders and coatings are prepared and studied to reveal the effect of nano-MoS₂ on the friction and wear behavior of the coating. The morphology, surface roughness and hardness are observed and measured by a scanning electron microscope, a laser scanning confocal microscope and a micro-hardness tester. The ability to resist fracture of the coatings is evaluated by scratch tests. The friction and wear tests of the coatings are conducted by a ball-on-disc tribometer. The experimental results show that AZ and AZM coatings have similar morphology and roughness. But nano-MoS₂ decreases the hardness and improves the ability to resist fracture of the coating. Besides, nano-MoS₂ decreases the coefficients of friction of the coating when the normal loads are high. The wear rates of AZM coating decrease by 38.7%, 29.7%, 23.6% and 11% compared with those of AZ coating under normal loads of 5N, 10N, 15N and 20N. The addition of nano-MoS₂ endows the coating self-lubricating function. The main wear mechanism of the coatings is micro-fracture accompanied by splat delamination and slight abrasion wear.