Effects of Heat Treatment on Thermal Expansion Coefficient of C/C Composites

Taking integral carbon felt as reinforced preform,the integral felt reinforced C/C composites were prepared by means of combination process of chemical vapor infiltration(CVI) and resin impregnation carbonization(PIC).Effects of heat treatment on thermal expansion coefficient were studied.The results show that with the heat treatment temperature(HTT) raising from 1800℃ to 2500℃,the axial CTE at 1000℃ decreased from 3.30×10-6/℃ to 3.00×10-6/℃,while from 2.28×10-6/℃ to 2.10×10-6/℃ with times increasing from 1 to 2 times.Meanwhile,The CTE decreased by 24% as porosity increased by 84%.It can be concluded that microstructure of C/C composites is improved,graphitized degree is strengthened,and porosity is increased through heat treatment.It is possible to decrease integral CTE and improve the thermal stabilization of C/C composites with appropriate heat treatment technology.