高温处理过程C/C复合材料微结构演变规律

对热解炭基、热解炭-树脂炭基C/C复合材料进行了1 500、1 800、2 100、2 500℃高温热处理。采用X射线衍射仪、激光拉曼光谱仪,对不同热处理温度及未进行热处理的2种C/C复合材料纳米尺度结构进行了表征;采用扫描电子显微镜、压汞仪,检测了其微米尺度孔隙缺陷。结果表明,随热处理温度的增加,微米尺度C/C复合材料的孔隙率逐渐增加,材料中裂纹型孔隙缺陷在热处理过程中,没有沿裂纹尖端的应力集中区域扩展,而是沿裂纹的宽度方向变化;纳米尺度C/C复合材料炭结构向理想微晶结构转变,缺陷逐渐减少,其变化趋势和微米尺度孔隙率的变化很相似。随热处理温度的增加,纳米尺度1-d002与微米尺度孔隙率呈线性关系趋势,并据此获得了用微米尺度孔隙率变化表征C/C复合材料石墨化度的经验公式。

Micro-structure evolution law of C/C composites during heat treatment process

Carbon/carbon composites of pyrocarbon matrix,pyrolytic-resion carbon matrix were treated at 1 500 ℃,1 800 ℃,2 100 ℃ and 2 500 ℃,respectively.Nano-dimension structure and graphitization degree of treated and untreated composites were characterized by X ray diffraction(XRD) and Raman Spectrum.Micro-pore defects were checked both by scan electronic microscope(SEM) and a mercury instrument.The results show that porosity increases gradually with increasing temperature.The crack type defects don’t expand along the tip of crack but width direction in the process of heat treatment.There exists a linear relationship between the porosity and 1-d002,so an empirical method for evaluation of graphitization degree under different micro porosity was proposed.