Wear Behaviour of Eutectic Al-Si Alloy-Graphite Composites Fabricated by Combined Modified Two-Stage Stir Casting and Squeeze Casting Methods

Dry sliding wear behaviour of eutectic Al-Si alloy-graphite composites was investigated employing a pin-on-disc wear test rig. Results revealed that the wear and friction coefficients decreased linearly with increasing weight percentage of graphite particles. Wear resistance of the composite increased considerably with increasing sliding velocity at constant load. In contrast, the friction coefficient of Al-7.5 wt.% Gr composite increased when the sliding velocity was increased from 1 m/s to 2 m/s at 49 N. Worn-out surfaces of wear specimens after the test were examined by scanning electron microscopy to study the morphology of worn surfaces. EDS analysis was carried out to investigate the influence of mechanically mixed layer (MML) which comprises oxides and iron, and this acted as an effective tribolayer in enhancing the wear resistance at higher sliding velocity

Synthesis of Al-Fly Ash Composites by Modified Two Step Stir Casting Method

Abstract. In the stir casting process, homogeneous dispersion of reinforcing particles within the matrix material is one such major problem, which influences on the properties of composites. In this research, an attempt has been made to study the influence of fly ash wt.% (10 ,15 and 20), ratio of the impeller outer dia to crucible inner dia (0.7,0.5 and 0.3) and processing method (liquid state stirring, two step stirring and modified two step stirring) on the mechanical properties and the distribution of fly ash particles in the Al matrix.Optimum parameters were identified for attaining the maximum mechanical properties such as hardness and tensile strength of composites by the application of Taguchi method, Analysis of Variance (ANOVA) and the results were validated by confirmation test.The present work could provide a guide for the industrial preparation of composites