烧结助剂对反应热压烧结B_4C基复合材料性能的影响

Influence of sintering additive on the performance of B_4C based composites sintered by reaction hot-pressing

以微米级B4C粉体为原料,通过与TiO2和葡萄糖原位反应制备TiB2颗粒增韧B4C复合材料。研究了烧结温度和烧结助剂对材料烧结行为及力学性能的影响。在1950℃反应热压下获得了相对密度为97.7%的TiB2/B4C复合材料,断裂韧性达到5.3 MPa.m1/2。添加Al2O3和Si烧结助剂后,分别在1950℃和1900℃获得了接近致密的(TiB2,Al2O3)/B4C和(TiB2,SiC)/B4C复合材料,断裂韧性分别提高到7.09和6.35 MPa.m1/2。显微组织分析表明,增韧作用主要来自残余应力引起的裂纹偏转。

B4C based composites toughened by TiB2 were fabricated by in situ reaction sintering with the original microcrystalline powders B4C, TiO2 and glucose. The influences of sintering temperature and additive on the sintering behavior and mechanical properties were investigated. TiB2/B4 C composites with relative density of 97.70% were obtained by in situ reaction hot- pressing at 1950℃. The composites exhibit improved fracture toughness of 5.3 MPa· m1/2. （TiB2 , Al2O3 ）/B4 C and （TiB2 , SiC）/B4 C composites with almost full densification were fabricated by using additives of Al2O3 and Si powders and sintering at 1950℃ and 1900℃; the fracture toughness of composites reaches 7. 09 and 6. 35 MPa. m1/2 respectively. The analysis of microstructure shows that the main toughening mechanism is the crack deflection due to the existence of residual stress.