石墨颗粒增韧SiO_2基复合材料韧化机理

Toughening Mechanisms of Graphite Particulate Toughened SiO_2 Matrix Composite

真空热压烧结制成了石墨颗粒 (Cp)增韧 Si O2 陶瓷基复合材料 ,对其组织结构、力学行为和增韧机制进行了研究。由于石墨粒子具有明显诱导 Si O2 玻璃基体晶化的作用 ,Si O2 中引入体积含量为 1 0 %的 Cp 后 ,在基体强度水平仅轻微下降的同时 ,复合材料弹性模量明显降低 ,断裂韧性和断裂应变显著提高 ,且宏观上表现出明显伪塑性。片状石墨粒子的桥接、拔出、尤其是诱导裂纹偏转和诱发微裂纹 ,是材料及韧化显现伪塑性的主要原因。

Graphite particles (C P) toughened SiO 2 matrix composite was fabricated by vacuum hot-pressing. Its microstructure, mechanical behavior and toughening mechanisms was investigated. It is indicated that because graphite particles has the significant function of inducing the crystallization of SiO 2 glass matrix, so when 10% (vol.) graphite particles are mixed with SiO 2, the fracture toughness and fracture strain of the composite are remarkably improved and apparent pseudo-plastic behavior emerges, as well as the young's modulus successfully decreases with only a slight degradation of the strength. The bridging and pulling-out effect of the flake C p and particularly the microcracking and crack deflection from the C p are regarded as the principal reason for the pseudo-plastic behavior of material and toughening mechanisms.