Experimental Investigation and Taguchi Optimization of the Tribological Properties of Boron Carbide Reinforced Aluminum Matrix Composites
Abstract
In this study, the tribological performance of A7075 aluminum matrix composites reinforced with 5% B4C was investigated using the dry pin-on-disk method in accordance with the ASTM G99 standard. The effect of three different loads (10, 20, 30 N) and three different sliding speeds (1, 1.5, 2 m/s) on wear behavior was evaluated at a constant friction distance of 2500 m. Taguchi S/N ratio analysis was used to determine the relative effects of the parameters and the optimal conditions. The analysis results revealed that the most effective factor on both mass loss and friction coefficient was the applied load, while the effect of sliding speed remained secondary. The test results showed that the increasing load increased mass loss in accordance with Archard's Law but significantly reduced the average coefficient of friction (COF). This decrease in COF has been attributed to the protective tribo-film formed by the effects of increased load and surface temperature. This film reduced metallic contact and lowered friction by creating a solid lubricant effect. However, the fluctuations observed in the COF curves indicate that this film is not fully stable and continuously forms and breaks down during wear. The effect of sliding speed was not linear; specifically, under high load (30 N) and medium speed (1.5 m/s) conditions, the mass loss decreased compared to low speed (1 m/s) (39 mg vs. 33 mg), indicating that the protective layer became more effective under certain conditions. According to the optimization results, the most suitable values were determined to be 10 N for minimum wear and 30 N for minimum friction coefficient. The prediction accuracy of the developed statistical models was found to be high for COF (82.97%) and relatively low for mass loss (35.19%). This indicates that mass loss is strongly influenced by complex, nonlinear mechanisms such as tribo-film formation and thermal softening.