Effect of Lubrication on the Wear Resistance of Plasma Sprayed Composite Coatings (Al2O3+ZrO2∙5CaO)

Abstract

Tribological investigations were carried out as per ASTM G134 standard, on plasma sprayed composite coatings (Al2O3+ZrO2·5CaO), under dry and wet abrasive conditions. 20W40 lubricating engine oil was used as a lubricant. Experiments were carried out under normal loads of 10, 15, & 20N, and at a rotational speed of 200 rpm. Scanning Electron Microscopy was used to study the surface characteristics of the as-sprayed and worn out topcoat. Results obtained from the SEM analysis revealed that abrasive wear was mainly governed by third-body abrasion (twinning effect) under dry abrasive conditions. A significant drop in wear rate was realized under the wet lubricated condition, between 10 and 15 N normal loads and a rise in wear rate was observed above 15 N normal load. At higher load, the lubrication was not very effective. At higher loads, It was also observed that the connection between grains improved leading to reduced micro porosity. This caused less abrasion and greater sliding. Experimental data obtained in this work is of good engineering significance as it can be applied to various engineering applications viz. internal combustion engines, cutting tools, etc.