Natural Gas As A Carbon Source Cvi Preparation Of C / C Composite Materials Research

The microstructure of pyrocarbon is crucial to the perfoemance of C/C composites,changing the parameter to accquire right structure of pyrocarbon and increse the efficiency is one of the hot subjects both domestic and international research. Now, C/C composites are widely prepared by propylene, but the gas using efficiency is low, and because of propylene is expensive so the cost of production is high, these facts hinder the development and applications of C/Ccomposites. Therefore, it is essential to develop new precursors which can cut down the cost of production and make C/C composites is competitive in marketplace. The present research work aims to the foregoing need, perpared C/C composites from natural gas by ICVI, studing the effects of different parameters such as temperature,pressure,residence time on the densitification rate and microstructure of C/C composites, the conclusion as the follows:(1)The temperature is a important parameter to CVI, when the pressure is lOKPa, as the temperature rose from 1000℃to 1100℃, after 100h deposition, the density of sample is 1.38 g/cm3, as the temperature reached 1150℃, the density of sample decreased from 1.38 g/cm3 to 1.32 g/cm3。The pyrocarbon in the C/C composites which were prepared at 1100℃is RL(2)When the temperature is 1100℃, as the pressure varied from 1KPa to 15KPa, after 100h deposition, the density of sample increased from 1.08 g/cm3 to 1.58 g/cm3, and increasing the pressure is useful to densification. The pyrocarbon in the C/C composites prepared at the pressure of 15 KPa is Banded which is make up of RL and SL; The pyrocarbon in the C/C composites prepared at the pressure of 10 KPa and 12KPa is RL.(3) When temperature is 1100℃and pressure is 10KPa, as the residence time prolonged from 0.13s to 0.32s, the density of sample increased from 1.20 g/cm3 to 1.46g/cm3, as the residence time is 0.4s, the density of sample is 1.05 g/cm3. When the residence time is 0.22s and 0.32s, the pyrocarbon in the C/C composites is RL.(4) Applying the orthogonal experiment design, we know that the pressure of precursors is a determinant factor to the densitication of the porous performs; and the residence time is a determinant factor to the structure of pyrocarbon, and by the orthogonal experiment design we accquire the best CVI parameter in this experiment. The best parameters are as the follows:1100℃,12KPa,0.32s.