Evaluation of physical, mechanical and sliding wear properties of in-situ AB-TiC composite: a comparison with NAB alloy

Abstract

The present study compared the physical, mechanical, and sliding wear response of cast in situ aluminium bronze (AB)-TiC [(Cu10Al3Fe)5TiC] composite to that of cast nickel aluminium bronze (NAB) [Cu10Al5Ni5Fe] alloy. To investigate wear loss, frictional heating, and friction coefficient, a pin type test material was employed against a rotating heat-treated EN-31 steel disc to conduct sliding wear test in dry and partially lubricated conditions. The NAB alloy exhibit higher tensile strength (32.7%), compressive strength (7.68% at room temperature and 4.18% at 500 oC), hardness (8.78%), and density (3.17%), whereas the AB-TiC composite showed higher thermal conductivity 4.89% than the NAB alloy. In terms of wear resistance under dry sliding conditions, composite outperformed NAB alloy up to a threshold applied load and/or sliding speed, beyond which the trend altered. Increasing sliding speed resulted into reduce wear transition load, while friction coefficient showed a mixed trend. Under lubricated test conditions, AB-TiC composite displayed considerably higher wear resistance (50.08%, 44.41% & 51.55%) and friction coefficient (26.37%, 40.75% & 14.96%) than the NAB alloy when tested in only oil, oil with 100 µm graphite and oil with 7-10 µm graphite respectively. Arrival of seizure in general caused significantly higher wear loss and temperature rise which caused large adhesion of specimen material to the disc surface. The reported wear behaviour of the samples has been validated using the features of wear surfaces and subsurface regions. The analysis significantly shows good impacts of the oil lubrication in terms of decreasing wear rate, frictional heating, and friction coefficient. Formation of steady lubricating film was reported to be responsible for the better wear performance. Furthermore, irrespective of material composition and microstructure, there exists a precise set of test parameters leading to optimal wear performance wherein the beneficial impacts of load bearing capability, thermal stability of various phases predominates.