Effect of the loads on the wear resistance of the Cr2O3-TiO2 coated AA 6082 alloy under unlubricated conditions

In the present study, AA 6082 was coated with Cr2O3-TiO2 powders by using flame spraying technique and wear behavior determined in a block on disc configuration under dry sliding conditions at different loads (20, 30 and 40 N). The selected initial load was kept constant for the rest of the sliding. The optical microscope and SEM were used to examine for both of the microstructure of the layers and the wear tracks. The phases in the coating were analyzed with x-ray diffraction and the hardness value of the layer was also obtained with a Vickers microhardness tester. The average hardness values of the coating was 925 HV. Due to the higher hardness values of the coating, the weight loss is very low especially lower loads like as 20 N. Increasing the load from 20 N to 30 N, weight loss is increased and the abrasive wear mechanism becomes effective. Surprisingly after the 40 N loads mass loss was decrease due to the plastic deformation. This observation shows that the plastic deformation of the coating due to a critical load reduces abrasive wear by preventing the ceramic particles from breaking away.