Fretting wear behavior of conventional and nanostructured Al2O3–13 wt%TiO2 coatings fabricated by plasma spray

The fretting wear behavior of conventional and nanostructured Al2O3–13 wt%TiO2 coatings fabricated by plasma spray was studied in this paper. The conventional coatings were deposited with commercial Metco 130 feedstock, and the nanostructured coatings were deposited with agglomerated feedstock with nanostructure. There were typical lamellar structures existing in conventional coating, however, those were not obviously observed in nanostructured coating. Amorphous phases, nanosized grains and some submicron grains existed in nanostructured coating. In fretting wear tests, the coatings wear against 52100 steel ball. In all of three conditions tests, the fretting maintained in gross slip regime for both nanostructured and conventional coatings. The coefficient of friction (COF) ranged from 0.7 to 0.9 in the fretting wear test. There was a transfer iron oxide layer formed on the worn coating surface. Fretting cracks propagate along the splat boundary in conventional coatings but propagate at random in nanostructured coatings. Test results showed that nanostructured coatings exhibited much better fretting wear resistance than conventional coating. The improved fretting wear resistance of nanostructured coatings was attributed to the nanosized grains, reduced lamellar structures and amorphous phases.