(哈尔滨工业大学复合材料研究所， 哈尔滨 150001)
摘 要: 通过B2O3-Mg-C体系的自蔓延高温还原反应，成功地制备出了B4C粉。由于Mg 的高挥发性，Mg与B2O3的反应受到环境气压的影响。低压下燃烧时，由于Mg的挥发造成燃烧温度低于B的熔点，生成的B4C颗粒尺寸约0.4 μm。10 MPa下反应物的挥发受到抑制，使燃烧温度达到或超过硼的熔点，生成的B4C颗粒尺寸约5 μm。在100 MPa下，由于氩气的热导率增加，使得热损失增加，造成燃烧温度反而较10MPa下有所降低。燃烧温度曲线在硼熔点 附近出现的等温线证实了分步反应机理的存在。
关键字: 燃烧合成 热还原反应 气压 B4C
（Center for Composites Materials, Harbin Institute of Technology, Harbin 150001, P. R. China）
Abstract:B4C was fabricated successfully by SHS in B2O3-Mg -C system. The interaction between the reducing agent Mg and B2O3 depends on the surrounding inert gas pressure due to the high volatility of Mg. Under low pressure, the volatility of Mg causes the combustion temperature below the melting point of B and the particle size o f B4C is about 0.4 μm. Under high pressure, the vapourization of Mg is reduced, thus the combustion temperature reaches the melting point of B, and the grains of B4C grow to about 5μm. The higher thermal conductivity of Ar under 100 MPa causes the heat loss increase and the combustion temperature is lower than that under 0.1MPa. The sequential mechanism is supported by an isothermal step observed at the melting point of B in the combustion temperature profile.
Key words: combustion synthesis; thermal reduction reactions; pressure; B4C
