Self-healing and Oxidation Resistance of B-Si Doped Carbon Materials Derived from Modification Coal Tar Pitch

Abstract With toluene soluble fraction of coal tar pitch, polycarbosilane and pyridine borane as raw materials, the modification coal tar pitch was synthesized by a liquid method. The B-Si-doped carbon materials were obtained by carbonization treatment at 800–1,600 °C for 1 h. The effects of carbonization temperatures on the composition, microstructure and oxidation resistance of the B-Si-doped carbon materials were investigated by XRD, SEM and TG-DSC. The results showed that the B-Si-doped carbon materials were composed of B ₂ O ₃ and carbon. SiC crystal grains appeared when the carbonization temperatures were over 1,200 °C. The higher the carbonization temperatures were, the larger the SiC grain sizes of B-Si-doped carbon materials became. But oxidation rate of larger grain sizes of SiC was slow during oxidation. It was difficult to form a protective glassy film on the surface of the materials rapidly. Therefore, the B-Si-doped carbon materials obtained by carbonization at 1,200 °C showed better oxidation resistance. Oxidation resistance mechanism of B-Si-doped carbon materials was illustrated. The SiO ₂ produced by the oxidation of SiC and B ₂ O ₃ formed protective glassy film, which had self-healing and anti-oxidation synergism.