Synthesis, mechanical and tribological behaviours of boron nitride reinforced AA7075 composites produced by stir casting technique

Abstract

This experimental investigation focused on synthesis of aluminium 7075-boron nitride (BN) composites (AA7075-BN), using stir casting technique. Four various proportions of BN of 0, 4, 8 and 12 wt.% were used for the production of the composites. Scanning electron microscopy (SEM) was used to study the microstructure of the prepared composites. Using a pin-on-disc equipment, wear test was performed to analyse the tribological characteristics of the as-casted composites. The wear rate (WR) and the co-efficient of friction (COF) were determined by altering the input parameters, such as reinforcement (R), applied load (L), sliding velocity (V) and sliding distance (D). A grey relational technique (GRT) was applied to determine the appropriate conditions of parameters and showed low WR and COF for the composites. From the experimental results obtained, the least density of the composite was 2.70 g/cm 3 for AA 7075-12 wt.% BN. The mechanical properties of the composites were significantly improved. The highest tensile strength of 210 MPa was obtained from the same AA 7075-12 wt.% BN. There was 26% of improvement in the tensile strength with 4 wt.% of BN reinforcement in AA7075 matrix. Finally, the worn surface morphology confirmed plough and furrow formations on the AA 7075- 4wt.% BN and AA 7075-8 wt.% BN composites, respectively. Therefore, the applications of the various composites depend on their responses to the properties, as studied.