Microstructure and wear properties of Al_2O_3-CeO_2/Ni-base alloy composite coatings on aluminum alloys by plasma spray

摘要

Al_2O_3 and CeO_2 particles reinforced Ni-base alloy composite coatings were prepared on aluminum alloy 7005 by plasma spray. The microstructure, microhardness, fracture toughness, critical bonding force and the wear behavior and mechanisms of the composite coatings were investigated. It is found that CeO_2 particles can refine crystal grains, reduce porosity and unmelted Al_2O_3 particles in the composite coatings. The microhardness, fracture toughness, critical bonding force and wear resistance of the composite coatings are enhanced due to synergistic strengthening effects of Al_2O_3 and CeO_2 particles. The friction coefficients and wear losses increase as loads increase. At the loads of 3-6 N, the composite coatings experience local plastic deformation and micro-cutting wear. At the loads in the range of 9-12 N, the calculated maximum contact stress and maximum tensile stress on friction surfaces increase leading to plastic deformation induced working hardening. The wear mechanisms change into micro-brittle fracture wear and slight oxidative wear.