The effect of copper content on the wear resistance of MMC composites (Fe-C-Cu-SiC)

The aim of this study is to achieve an optimal chemical composition in the metal matrix composite (MMC) (Fe-C-Cu-SiC) to enhance the wear resistance of the composite and evaluate its mechanical properties based on the optimal amount of copper, making it suitable for use in brake pads for aircraft, locomotives, and racing cars. For this purpose, Fe, C, and BaSO₄ with a chemical composition of (6SiC-6.5C-6BaSO₄-Fe) and varying amounts of copper (3%, 7%, 11%, 15%, and 19%) were mechanically milled using powder metallurgy. The materials were then sintered in a furnace with protective gas and hot-pressed at 1000°C and 400 MPa, resulting in five test samples. Wear and friction coefficient tests were conducted under a load of 20 N, at 700 rpm, over a distance of 1000 m. Hardness tests, density measurements, microstructural examination with a scanning electron microscope (SEM), and EDAX analysis were also conducted to assess the wear mechanism. Examination of the worn surfaces indicated that during the initial sliding distance, the predominant mechanism was abrasion. As the sliding distance increased, abrasive and oxidation wear mechanisms, along with plastic deformation, became active. Test results showed that the Fe-15Cu-6.5C-6SiC-6BaSO₄ sample had higher wear resistance and a more suitable friction coefficient (within the acceptable range of 0.2 to 0.4) compared to the other four samples, suggesting its potential application for brake pads.