Technique Research Of Carbon/Carbon Composite Prepared By ICVI Method With Natural Gas And Hydrogen Gas

Abstract:C/C composite is one kind of excellent structure material. It has been widely used in aeronautics, astronautics and national defense and military field. During many preparation methods, the most widely used technology for producing C/C composite is ICVI method. The most focused area is about how to get high performance C/C composite by controlling the infiltration condition. In this study, based on previous researches, C/C composite with different thickness were prepared by using ICVI method with natural gas as carbon source gas and hydrogen used as diluent gas. The effect of gas pressure and infiltration temperature on the deposition rate and microstructure of PyC have been studied in order to find out appropriate infiltration condition for C/C composites with different thickness. The results are as follows:(2) In order to study the effect of gas pressure on the densification rate and microstructure of C/C composites, infiltration pressure changed in the range of8～20kPa. The results show that densification rate increased with increasing temperature and high infiltration pressure in favor of depositing high-textured PyC.(2) Carbon fiber preforms with a density of0.4g/cm3and10mm in thickness can be densified to1.85g/cm3by using isothermal chemical vapor infiltration method at the temperature of1120℃and a pressure of20kPa within70h. The pyrolytic carbon of prepared C/C composites was almost all consisted of RL(3) Carbon fiber preform with a density of0.3g/cm3and30mm in thickness, infiltrated at the temperature of1120℃and a gas pressure of20kPa for135h, the average density of prepared C/C composite was about1.71g/cm3. The density of surface area apparently higher than the inner area and the matrix of surface area almost just consist of RL, while the inner matrix consist of one layer of RL inside and one layer of ISO outside.(4) In order to eliminate density gradient in thickness direction and confirm the effect of temperature on microstructure of C/C composites, carbon fiber preforms infiltrated at the temperature of1030℃,1060℃, 1090℃for25h each. Results indicated that density gradient in thickness direction can effectively eliminate by decreasing infiltration temperature, but the texture of PyC decreased with decreasing temperature.