The abrasive wear behaviour of Al-SiC

Abstract

The present work reports on the continuous abrasives wear behaviour of Al-SiCp composites with 5 to 30 wt. % of SiC particulates. A pin-on-drum wear-testing machine was designed and fabricated to study the effects of wt. % of SiCp, load, relative velocity and abrasive particle characteristics on abrasive wear behaviour of Al-SiCp composite with 5 to 30 wt. % of SiCp. The 6040Al-SiCp composite samples were fabricated through stir die casting process using induction furnace melting. 6040 Al-alloy was used as matrix material, which was reinforced with SiC particles of 120μm mean particle size. The Al-SiCp composite specimens with 5, 10, 15, 20, 25 and 30 wt. % of SiCp were cast in the shape of cylindrical pins for abrasive wear testing. The specimens were machined to step pin of 5 and 16 mm diameter and length was 10mm and 45 mm. The specimens were slid against alumina oxide abrasive paper pasted on the drum with four different grit sizes i.e. number 120, 100, 90 and 80 at sliding velocity of 0.2, 0.4, 0.6 and 0.8 m/seconds respectively under different loads of 4.5 N, 9N, 14.5N and 18.5N for a fixed sliding distance of 0.5 m using Pin-on-drum wear testing machine. The weight loss due to wear of pins was measured using an electronic balance of 0.001 mg accuracy. The coefficient of friction was determined during the test using load cell unit. The results of the wear tests showed that the abrasion wear resistance decreases with increase in the relative abrasive penetration depth, until a critical value, above which, the abrasive wear resistance was almost independent of the penetration depth. The wear resistance was found to increase with the increase in weight percent of SiCp from 5 to 20 wt. %. However the wear resistance was decreases on further increase in wt. % of SiCp from 20 to 30 wt. % due to removal of loosely bonded SiC particles. The wear resistance was also found to increase with increase in normal load and decreased with increasing in sliding velocity. Abrasion by the Al2O3 particles and cavitations due to dislodging of SiC particles was identified as the dominant wear mechanism from the scanning electron micrographs of worn surfaces of the composites.