Tribological properties of plasma sprayed Al/Al2O3 composite coatings

Al2O3 and Al/Al2O3 composite coatings were prepared by atmospheric plasma spraying. The wear and friction properties of both coatings were evaluated under different degrees of severity using a block-on-ring arrangement. It was found that the wear resistance of the Al/Al2O3 composite coating was superior to that of the Al2O3 coating. The improvement in wear resistance of the Al/Al2O3 composite coating was attributed to its higher fracture toughness and adhesion strength as well as better thermal diffusivity. As for the Al/Al2O3 composite coating, the mechanism was mainly adhesion with micro-abrasion and fatigued-induced brittle fracture within splats, and the delamination along splat boundaries only occurred at high load. However, the failure of the Al2O3 coating was predominantly detachment of transferred film and brittle fracture within the splats and delamination along splat boundaries, which were enhanced with the increasing load.