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

Abstract

The purpose of the present study is to evaluate the physical, mechanical and sliding wear properties/response of cast in-situ aluminium bronze (AB)-TiC [(Cu10Al3Fe)5TiC] composite and compare with cast nickel aluminium bronze (NAB) [Cu10Al5Ni5Fe] alloy. Sliding wear tests were conducted in dry and partially lubricant conditions using a pin-on-disc machine. A test material in the form of pin was evaluated against a rotating heat-treated EN-31 steel disc. Wear loss, frictional heating and friction coefficient properties were examined. The NAB alloy showed higher tensile strength (32.7%), compressive strength (7.68% at room temperature. and 4.18% at 500 °C), hardness (8.78%) and density (3.17%), whereas thermal conductivity of the AB-TiC composite was found 4.89% higher than NAB alloy. In dry sliding condition, composite outperformed NAB alloy in terms of wear resistance up to a critical applied load and/or sliding speed. Beyond this point, the wear behavior altered. Increasing sliding speed caused to reduce wear transition load. While friction coefficient showed mixed trend. Under lubricated wear 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. In addition, it caused large adhesion of the 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 latter also permitted to comprehend the working wear processes. The analysis significantly shows good impacts of the oil lubrication (with and without solid particles) in terms of decreasing wear rate, frictional heating, and friction coefficient. Formation of steady lubricating film/layer was reported to be responsible for the better wear performance of the samples. Furthermore, irrespective of material composition and microstructure there exists a precise set of test parameters (e.g. load and speed) leading to optimal wear performance wherein the beneficial impacts of load bearing capability, thermal stability of various phases predominates.