Abstract: B4C-C composite powder was synthesized from carbon black and boric acid by carbothermal reduction reaction. The effect of heating temperature on the synthesis of B4C-C composite powder was studied. The phase composition, morphology, structure and particle size of synthesized composite powder were characterized by XRD, carbon and sulfur analyzer, SEM, and laser particle size analyzer. The effects of the synthesized composite powder added in MgO-C brick were investigated by measuring the physical properties, oxidation resistance, and thermal shock resistance of specimens. The results show that the graphitization degree of the synthesized B4C-C composite powder rises, while B4C phase decreases with increasing of heating temperature. The graphitization degree of the composite powder synthesized at 1900℃ is 23.26%, the percentage of B4C is about 20%. The differential distribution of the synthesized composite powder is above 85% nanometer B4C and partly graphitized carbon black, except some micron and submicron B4C particles. The physical properties, oxidation resistance, and thermal shock resistance of the low carbon MgO-C brick specimens added with the synthesized B4C-C composite powder are excellent.

Key words: carbon black, boron carbide, graphitization, low carbon MgO-C brick

摘要： 以炭黑和硼酸为原料，采用碳热还原法合成了部分石墨化B4C-C复合粉体，并将其作为碳源和抗氧化剂用于低碳镁碳砖中. 研究了加热温度对B4C-C复合粉体合成的影响，分析了其物相结构、成分、形貌和粒度. 通过测定低碳镁碳砖的常规物理性能、抗氧化性和热震稳定性，考察了复合粉体对低碳镁碳砖性能的影响. 结果表明，随加热温度升高，B4C-C复合粉体的石墨化度增大，B4C含量下降，1900℃时石墨化度达23.26%，B4C含量为20%左右，复合粉体中除部分微米、亚微米级的B4C外，85%以上为纳米级的B4C和部分石墨化炭黑. 添加复合粉体的低碳镁碳砖具有良好的常规物理性能、抗氧化性和热震稳定性.

关键词: 炭黑, 碳化硼, 石墨化, 低碳镁碳砖