低压化学气相渗透法制备2.5维SiCf/SiC复合材料

采用低压化学气相渗透法制备了具有和不具有热解炭界面层的2.5维连续SiC纤维增强的SiC复合材料(SiCf/SiC).SiC纤维的体积分数为30%和41%.所制备复合材料的气孔率为20%左右.当纤维为30%时,沉积有0.1 μm热解炭界面层的复合材料的弯曲强度由未加热解炭界面层的232MPa增加到328MPa,而且材料由灾难性断裂转变为非灾难性断裂.在同一制备条件下,纤维体积分数为41%的SiCf/SiC比30%的SiCf/SiC具有更高的气孔率.纤维为41%时,热解炭界面层厚度为0.1 μm的SiCf/SiC的弯曲强度只有244MPa,但是它具有更高的韧性和更长的纤维拔出长度.

2.5-DIMENSION SiCf/SiC COMPOSITES FABRICATED BY LOW PRESSURE CHEMICAL VAPOR INFILTRATION

2.5-dimension continuous silicon carbide fiber reinforced silicon carbide composites (SiCf/SiC) on the interface with and without a pyrocarbon layer were fabricated by low pressure chemical vapor infiltration. The volume fractions of SiC fiber were 30% and 41%. The porosity of the fabricated composites was about 20%. The flexual strength of the SiCf/SiC composite with 30% fiber and having an interface pyrocarbon layer about 0.1 μm thick increased from 232 MPa to 328 MPa and the fracture behavior changed from catastrophic failure to non-catastrophic failure compared with the composite without the pyrocarbon layer. The porosity of the composite slightly increased with the increase of fiber volume fraction from 30% to 41% when the fabrication process conditions were same. The flexural strength of SiCf/SiC with 41% fiber and an interface layer about 0.1 μm thick was only 244 MPa, but the fracture toughness was greater and the length of fiber pull-out was longer.