Experimental Investigation on Two-Body Abrasion of Cast Aluminum-Alumina Composites: Influence of Abrasive Size and Reinforcement Content

The occurrence of abrasion is inevitable in most engineering systems. Abrasive wear specifically two-body causes higher material and dimensional loss than other modes of wear. Two-body abrasion is yet to be fully comprehended as it is governed by several intrinsic and extrinsic variables. In this article, tribo-performances of Al-composites were experimentally studied with specific emphasis on the role of abrasive size and amount of reinforcement. AA7075 alloy matrix composites with different amounts of alumina particles were fabricated by the advanced stir-casting method. Besides measurements of density, porosity, and Vickers hardness, in-depth characterizations of microstructures were performed. Specific wear-rate (SWR), coefficient of friction (COF), and abraded surface roughness (SR) of developed materials were measured under two-body abrasion over a vast range of distance, load, velocity, and abrasive size. Under all abrasion conditions, composites exhibited higher SR but lower SWR and COF over alloy; the differences increased with reinforcement quantity. SWR, COF, and SR rose with an increase in abrasive size; however, only SR varied with sliding distance for any material. The effects of different variables on the recorded tribo-performances were explained through identification of various micro-mechanisms of abrasion via extensive post wear characterizations and microstructural features. Finally, the criteria for the occurrence of three-body abrasion even in two-body test configuration were highlighted. The wear coefficient value of 10 x 10(-3) was identified as the demarcation between two-body and two-body plus three-body abrasion for Al-matrix composites.