Tribological properties of nanostructured zirconia coatings deposited by plasma spraying

The nanostructured and traditional zirconia coatings were deposited by atmospheric plasma spray. The friction and wear properties of these two zirconia coatings against stainless steel were investigated with a block-on-ring tester under dry friction conditions. It was found that the plasma-sprayed nanostructured zirconia coating possessed better wear resistance than that of traditional zirconia coating. The wear rates of the nanostructured zirconia coatings are about two-fifths of those of traditional zirconia coatings under loads from 20 to 80 N. The improved wear resistance of the nanostructured zirconia coatings is attributed to the optimization of microstructure and the enhancement of mechanical properties, which improved the ability of plastic deformation of materials. The wear for both of two zirconia coatings is abrasive wear resulting from brittle fracture under low load (20 N). But under high load (80 N), the wear of nanostructured zirconia coating is explained in terms of plastic deformation and microcracking, while the wear of traditional zirconia coating is interpreted in terms of plastic deformation and brittle fracture.