Preparation and characterization of carbon block with coal tar pitch and phenolic resin as mixed binder

Here we present a method to prepare carbon block with excellent mechanical strength by using coal tar pitch and thermoplastic phenolic resin as a mixed binder and hexamethylene tetramine as a crosslinker. The effect of phenolic resin content in the mixed binder on properties of carbon blocks was investigated. In addition, the viscosity and fluidity of the mixed binder before and after crosslinking, and the evolution of size and pore structure of the carbon block during carbonization were systematically explored. The results revealed that the mixed binder had both low viscosity in the mixing stage and low fluidity in the carbonization stage. The low viscosity was favorable for its mixing with the pitch coke. Compared to carbon blocks with coal tar pitch binder, those with mixed binder had higher volume shrinkage during carbonization, especially the strong shrinkage at 700 °C which led to the large pore closure. The density, flexural, and compressive strength of the carbon block obtained by the mixed binder reached 1.56 g·cm−3, 34.4 MPa, and 131.3 MPa, while those of carbon blocks with the single binder were only 1.35 g·cm−3, 17.2 MPa, and 33.7 MPa.