摘要
以针刺网胎无纬布交替叠层准三维结构为预制体,采用热梯度化学气相沉积(TCVI)和树脂压力浸渍-炭化(PIC)混合致密方法得到不同密度的炭/炭复合材料,研究了密度和热处理温度对炭/炭复合材料弯曲和压缩性能的影响,并对其机理进行了探讨。结果表明:增大材料的密度可以提高材料的弯曲和压缩性能,破坏机理发生改变,密度较低时,弯曲破坏方式为"假塑性"的分层破坏模式,压缩破坏为压溃式破坏;高密度的试样,弯曲破坏为拉应力或压应力破坏模式,压缩破坏为剪切和分层破坏模式,表现出一定的脆性;热处理温度升高,降低了材料的弯曲和压缩强度或模量,但明显改变了材料的破坏模式,增多了裂纹扩展或偏转的途径,表现出更好的"假塑性";由分析得出,准三维炭/炭复合材料承压时,针刺处是力学薄弱点,易产生分层。
needled carbon fiber quasi three-dimensional integral structure was used as the preform, which was densified by thermal gradient chemical vapor infiltration （TCVI） and resin pressure impregnation-carbonization （PIC） processes to gain carbon/carbon （C/C） composites of different densities. Effects of density and heat treatment temperature （HTT） on bending and compression performance of C/C composites were researched, and the mechanism was also discussed. The results show that the bending and compression properties increase and the mechanism changed with the higher density. Mechanical damage model of the C/C with a low density can be understood as ＂pseudoplastic＂ delamination model of bending and press-damage model of compression, yet tensile or compression stress damage model when the C/C endured bending load, and shear and delamination damage model when the C/C with endured compression load, and the C/C with a higher density presents brittleness. The bending and compression strength or modulus decrease with the increasing HTT, and the damage model changes, such as increasing the path of crack expansion or yawing and showing better ＂pseudoplastic＂. When the samples are compressed, weak mechanical points exist at the needling place, which easily leads delamination.
出处
《材料科学与工程学报》
CAS
CSCD
北大核心
2008年第5期693-696,692,共5页
Journal of Materials Science and Engineering
关键词
炭/炭复合材料
力学性能
破坏模式
Carbon/carbon composites
mechanical property
damage model
