Friction and wear behaviour of HVOF sprayed Cr<SUB align="right">2O<SUB align="right">3-TiO<SUB align="right">2 coatings on aluminium alloy

Abstract

This study investigates the tribological behaviour of Cr2O3-TiO2 composite coatings deposited on aluminium 6061 alloy. Cr2O3-TiO2 composite coatings were deposited by high velocity oxyfuel (HVOF) technique. Developed coatings were subjected to microstructure studies, microhardness test (ASTM E92), friction and wear test (ASTM G99). Pin-on-disc machine was used to evaluate friction and wear characteristics of Cr2O3-TiO2 coatings. Effect of sliding velocity (0.314 m/s-1.26 m/s) and load (20 N-100 N) on friction and wear characteristics of Cr2O3-TiO2 coatings were studied and compared with uncoated aluminium alloy. Results showed 54% improvement in hardness of Cr2O3-TiO2 coatings in comparison with aluminium alloy. Coefficient of friction and wear rate decreases by 12% and 48% respectively when evaluated with uncoated aluminium alloy. Coefficient of friction (COF) and wear rate increases with increase in load and sliding velocity for both coatings and substrate. However, Cr2O3-TiO2 coatings showed lower wear rate and COF at all the loads and sliding velocities studied when compared with uncoated aluminium alloy. Worn out surfaces of uncoated and Cr2O3-TiO2 coated surfaces were subjected to SEM analysis to understand the wear mechanisms in composite coatings.