The main method to increase carbon carbon composite material oxidation resistance are surface coating technology and carbon matrix modification. The traditional methods mainly include carbon fiber modification, liquid phase impregnation, additive agent, matrix replacement etc.
Carbon carbon composite material has low density, high strength,high modulus,high thermal conductivity,low coefficient of expansion and thermal shock resistance etc. These properties can maintain under the 2000 centigrade,can make the carbon carbon composite material to be the preferred material of high thermal structure material, and it’s widely used in the aerospace field. However,most of the properties can only maintain under the inert environment. Carbon carbon composite material will occure oxidation when the tempterature reach 400 centigrade,the oxidation can reduce the strength of the material,and will limit the using under the high thermal condition.
The surface coating technology now is the most widely used method,the coating can make the material work under 1600 centigrade,but the different coefficient of expansion of coating and the carbon carbon composite material make it will occur very small crack,and this make the coating will not work under the low tempterature.
The oxidation resistance technology of carbon carbon composite material mainly devide into carbon matrix modification and surface coating,the carbon matrix modification is different from the surface coating because of it will bring the oxygen barrier composition to the carbon perform,and make the carbon matrix with a oxidation resistance,and the oxygen barrier composition need a good chemical compatibility with the carbon matrix,and low penetration ability,and no influence to the properties of carbon carbon composite material.
Make the oxidation resistance on the carbon fiber surface can reduce the oxidation velocity and protect the C/C material. And there are two methods to modify the carbon fiber,one is making the coating on the surface of the carbon fiber ,and another one is gas phase treatment on carbon fiber surface.