Vacuum Pressure Infiltration Manufacturing C/C Composite Preform

Carbon/carbon composite is a very important kind of new ultra high temperature material, which has been wildly used in high temperature area, since it possess so many advantages like low density, high specific strength, good high temperature mechanical properties, low coefficient of thermal expansion and so on. But, as result of the high processing cost, it was mainly used in military field which can overlook the cost. In recent years, as the preparation technology developing and maturing in the field, its application scope has been extended to the field of civilian. But the cost is still the most important factor that restrict its wide application. There are two main preparation methods of carbon/carbon materials, which are chemical vapor deposition method and liquid phase impregnation method respectively. This paper is dedicated to the study of liquid phase impregnation method, The main factors affect the cost of liquid impregnation method is impregnation efficiency.In this paper we will use appropriate carbon felt, and pure liquid thermosetting phenolic resin with moderate viscosity, combined with two different process of the vacuum pressure infiltration pressure holding solidification method, to analysis the influence of vacuum, pressure of impregnation, solidification heating rate and the solidification environment. Combining with the advantages of two kinds of process to summarize a set of the most beneficial process parameters of solidify and carbonize densification.1. In the process of solidification, the effect of densification by high pressure gas acting directly on the sample surfaces is better than those forces on the liquid surface. And after the impregnation, we can improve the utilization rate of the resin by draining excess resin.2. Although high pressure impregnation and low pressure impregnation share different impregnation mechanism, but the general rule is that the higher the density of the solidified sample the higher the density after carbonize. In terms of the resin separation pressure holding process, with the increase of sample curing pressure, the density of sample also presents obvious rising trend.3. In the process of impregnation, we should increase the pressure gradually rather than increase the pressure immediately, It is better to divide the whole process into several stages between low pressure and high pressure, ensure each stage can get enough time, and then drain the excess resin, holding pressure and solidify the sample. This method would allow more resin to get into the body of the carbon fiber, combined with applying appropriate high pressure in the process of solidification, It will be more conductive to improve the density of sample.4. As solidification heating rate slows down, solidification and carbonation density of sample has obvious improved, the sample prepared by the resin separation pressure holding solidification method shows the highest solidification density of 1.26g/cm3, the corresponding carbonization density is 0.91 g/cm3. So, considering the production cycle and the cost, reduce the heating rate of solidification reaction appropriately is also a good choice of improving the density of sample.