碳化硼颗粒级配对硅反应结合碳化硼复合材料结构与性能的影响

Effect of Boron Carbide Particle Size Distribution on the Microstructure and Properties of Reaction Bonded Boron Carbide Ceramic Composites by Silicon Infiltration

本研究探讨了碳化硼原料颗粒尺寸对反应结合碳化硼复合材料相组成、结构与性能的影响。研究结果表明:颗粒级配可以使粉体堆积更加密实,有效提高压制坯体的体积密度,最终降低复合材料中游离Si的含量;加入粗颗粒可减缓B_(4)C与Si的反应,减少SiC相的生成;当原料中粒径为3.5、14、28、45μm的B_(4)C粉体按质量比为1.5:4:1.5:3配比时,所制备的复合材料维氏硬度、抗弯强度、断裂韧性和体积密度分别为(29±5)GPa、(320±32)MPa、(3.9±0.2)MPa·m^(1/2)和2.51 g/cm^(3)。在制备复合材料过程中减缓B_(4)C与Si反应速度、减少游离Si的含量和缩小Si区域尺寸是其性能升高的主要原因。

Effect of particle size of boron carbide raw material on the phase composition,microstructure and properties of reaction bonded boron carbide composites was investigated.It was found that particle gradation can make the powder packing more compact and effectively improve the volume density of green body,decreasing the content of free Si in the composites.Addition of coarse particles can reduce the reaction between B_(4)C and Si,which can generate SiC phase.When the weight ratio of B_(4)C powders with different particle sizes(3.5,14,28,45μm)is 1.5:4:1.5:3,the Vickers hardness,flexure strength,fracture toughness and volume density of the composites are(29±5)GPa,(320±32)MPa,(3.9±0.2)MPa·m^(1/2) and 2.51g/cm^(3),respectively.The retard of reaction between B_(4)C and Si,and the decrease of free Si content along with the shrinkage of size of Si zone in the composites,are the main reasons for the improvement of the composite mechanical properties.