C/C-SiC复合材料致密度影响因素

利用先驱体转化法制备C/C-SiC复合材料,对试样进行微观结构分析和性能测试,研究渗硅温度、保温时间、真空度和裂解周期对C/C-SiC复合材料致密度的影响。结果表明:随着渗硅温度的升高,材料的致密度呈先加速升高后快速下降趋势;随着保温时间的延长,材料的致密度先快速升高,保持一段时间稳定后再缓慢降低;随着烧结真空度的提高,材料的致密度加速升高;随着裂解周期的增加,材料的致密度不断增大,但增速逐步降低。经过11周期的“浸渍-固化-裂解”过程后,所制备的C/C-SiC复合材料获得最大密度2.09 g/cm3、最小孔隙率7.6%,其综合力学性能最为优异:弯曲强度468 MPa、拉伸强度242 MPa、断裂韧度19.6 MPa?m1/2、维氏硬度17.2 GPa。

Factors affecting the density of C/C-SiC composite

C/C-SiC composites were prepared by precursor transformation method.The microstructure and properties of the samples were analyzed.The effects of silicon infiltration temperature,holding time,vacuum degree and cracking cycle on the density of C/C-SiC composite were studied.The results show that with the increase of siliconizing temperature,the density of the material increases at first,and then decreases rapidly.With the increase of heat preservation time,the density of the material increases rapidly at first,keeps stable for a period of time and then decreases slowly.With the increase of sintering vacuum,degree,the density of the material increases rapidly.With the increase of cracking cycle,the density of the material increases continuously,but the growth rate decreases gradually.After 11 cycles of“impregnation curing cracking”process,the C/C-SiC composite prepared obtained a maximum density of 2.09 g/cm3 and a minimum porosity of 7.6%.At this time,it also has the most excellent comprehensive mechanical properties:bending strength of 468 MPa,tensile strength of 242 MPa,fracture toughness of 19.6 MPa?m1/2 and Vickers hardness of 17.2 GPa.