ROLE OF FRICTION ENERGY AND TRIBO-REDUCTION IN ABRASIVE WEAR OF ALUMINA–TITANIA COATINGS

Abstract

This paper addresses friction energy-induced reduction of TiO2 during abrasive wear and friction of alumina–titania coatings with different TiO2 content. Alumina–13% titania and alumina–40% titania coatings were deposited by atmospheric plasma spray technique. An improvement in fracture toughness and better densification of coatings was observed with an increase in titania content. Alumina–40% titania coating showed lower friction coefficient and higher abrasive wear resistance than alumina–13% titania coating. An increase in friction energy was associated with enhanced reduction of TiO2 to Ti2O3 and an increase in the extent of gamma alumina to alpha alumina phase conversion. These observations along with structural and mechanical properties of coatings could explain differences in tribological response of these coatings. Friction energy parameter (FEP) was used to identify different regimes of wear and degradation mode of coatings.