Dry Sliding Wear Investigation of Centrifugally Casted AA6061–B₄C Functionally Graded Metal Matrix Composite Material by Response Surface Methodology (RSM)

The current study mainly focused on evaluating the dry sliding wear performance of centrifugally casted functionally gradient AA6061–8 vol% B₄C composite using response surface methodology (RSM). A cylindrical functionally graded material (FGM) component was produced with the combination of stir and horizontal centrifugal casting techniques. Metallographic characterization by scanning electron microscope has confirmed the gradual variation of B₄C particles from external to internal periphery of FGM. B₄C concentration and microhardness value were found to be maximum in outer and minimum in inner zone. A mathematical model is established for the outer zone of FGM to estimate response-specific wear rate considering applied load, sliding velocity, and sliding distance as wear parameters. Dry sliding wear tests were performed utilizing a pin-on-disk equipment in accordance with the central composite design of experiments. The high determination coefficient (R² = 0.9981) indicates the derived model's quality of fit. Furthermore, the optimal wear parameter condition was estimated using response optimizer, ensuing a predicted specific wear rate of 1.8051 × 10^–5 mm³/N-m. The validation test was conducted under optimum conditions, and the determined specific wear rate value by the experiment was found as 1.8843 × 10^–5 mm³/N-m, indicating reasonable accuracy between predicted and experimental specific wear rates. The morphology of worn-out surface for optimized conditions was analyzed with the help of scanning electron microscopy (SEM) images and energy-dispersive spectroscopy (EDS).