Controlling The Structure and Porosity of Carbon-Carbon Composites to Optimize their Electrical and Mechanical Properties

Carbon-carbon composites comprised of fillers dispersed in a carbonized binder matrix are widely used as high-power electrical contacts in rail transport and power generation. The formulation of the composite contains main components and is often empirical, routed in a century of industrial know-how. A key morphological parameter is the open porosity of the composites, which controls the physical and electrical properties and facilitates the infiltration of molten metal for higher-performance carbon-carbon-metal composites. Herein, the role of the different composites of the formulation was studied to understand their relationship to the porosity. Initially, a formulation for the fabrication of carbon-carbon composites using coal tar pitch as a binder and sulfur as a catalyst was designed. Needle coke, carbon black, and graphite were employed as carbon fillers. In the manufacturing process, different loadings of sulphur as well as the different content and types of carbon black were used to investigate the density, shrinkage, carbon yield, and open porosity of the composites. The experimental results revealed that increasing the loadings of sulfur and carbon black resulted in higher bulk density and reduced the open porosity of the carbon-carbon composites, which led to<br/>better mechanical properties. Additionally, the increase of carbon black content leads to an enhancement in the electrical conductivity of the samples.