Sustainable lightweight multifunctional carbon foams derived from coal tar pitch using urea as a pore-forming agent

Lightweight carbon foams have attracted great attention in the past several years due to their potential applications in heat sinks, heat exchangers, electrodes for battery and supercapacitors, fuel cells, adsorbents for pollutants, catalyst supports, electromagnetic interference shielding, and so on. Up to now, carbon foams have been synthesized by using various methods. However, in this present work, we propose a new method for the fabrication of lightweight carbon foams using coal tar pitch as a carbon precursor and urea particles as a pore-forming agent. First, the coal tar pitch was heated at 500 °C and converted into green coke. In the next step, different volume portions (0.2, 0.3, 0.4, and 0.5) of spherical urea particles were mixed with green coke, and then carbon foams with different porosities (60–80 %) were produced after molded into a cylindrical shape using a hydraulic press and then sintering at 1600ºC. The effect of urea particles on the structure, electrical, thermal and mechanical properties of the carbon foams was investigated. The results showed that by decreasing the urea content, the electrical, thermal, and mechanical properties of carbon foam increased significantly. The prepared carbon foam exhibits excellent electrical conductivity of 220 S/cm, compressive strength of 6.2 MPa, and thermal conductivity of 19 W/m.K whereas its relative density (ρrd) is 0.40. Different scaling relations were also used to measure the electrical, thermal, and mechanical properties of carbon foam theoretically.