Effect of TiC content on wear performance of A356 matrix composites  at different temperatures

Abstract

With the developing technology, aluminum matrix composites (AMCs) are widely used in many system parts in the automotive industry. One of the most important parts is the friction materials used in the brake system operating at varying temperatures. This study examined the wear performance of aluminum matrix composites produced by adding different amounts of TiC to the A356 matrix at different temperatures. TiC in 4 different amounts (3, 6, 9, and 12 wt.%) and 2% graphite as a solid lubricant were added to the A356 alloy. The powders prepared in mentioned proportions were mechanically alloyed for 240 min using a planetary mill. The AMCs were sintered for 60 min at 550 °C in a 10^–6 mbar vacuum environment. Afterward, the AMCs prepared through standard metallographic processes (sanding with 200–100 mesh sandpaper and polishing with 1 µm diamond solution) were characterized by scanning electron microscopy (SEM + EDS), X-ray diffraction spectroscopy (XRD), as well as hardness and density measurements. Wear tests were carried out by adding a temperature module in accordance with the ASTM-G99 standard. The study results showed a homogeneous distribution of TiC particles in the structure. Measurements showed that the hardness and density of the composites improved as the amount of reinforcement phase in the matrix increased. The highest hardness (821 HV) and the highest density (2.803 g/cm²) values were established for the AMC with 12% of TiC. The wear tests demonstrated that the weight loss was lower with the increasing reinforcement phase in the matrix. As the test temperature increased, the weight loss of the composites became higher. At all temperatures, the lowest weight loss was recorded for the AMC with the added 12% TiC. The coefficient of friction also increased with the higher temperature.