甲烷CVI工艺致密不同尺寸炭/炭复合材料实验与数值模拟研究

Experimental and numerical simulation studies on C/C composite with different dimensions via chemical vapour infiltration of methane

在温度为1348 K,压强15 kPa和停留时间1.0 s下,以甲烷为前驱体对两种不同厚度(16 mm和26 mm)2D炭纤维布预制体进行CVI热解炭致密。经120 h致密化后,将制备得到的炭/炭复合材料进行均匀切分,并测量样品的密度分布。实验结果表明,对于不同厚度的预制体,致密化后在气体流动的外侧密度都偏高,且样品密度都随着距气流外侧的距离增加而逐渐降低。通过耦合热解炭沉积反应机理和氢气抑制模型,模拟甲烷在两种不同厚度预制体的CVI致密化过程。计算获得的致密化后样品密度分布的模拟结果与实验结果较为接近,从而表明了该模拟方案的合理性与实用价值。

In this study,two 2D cloth performs with different thickness(16 mm and 26 mm)were densified by chemical vapour infiltration(CVI)of methane at a temperature of 1348 K,a pressure of 15 kPa,and a residence of 1.0 s.After 120 h densification,the obtained C/C composites were cut into pieces to measure the density distribution of the composites.From the experimental results of different thickness preforms,the density of the sample near the gas flow channel is higher than that of the inside of it,and the sample density decreases gradually with the distance from the gas flow channel.Along the direction of gas flow,the sample density is gradually reduced,and the density of the inside part of the sample decreases more rapidly along the direction of gas flow.By coupling the mechanism of pyrolytic carbon deposition and hydrogen inhibition model,the CVI densification processes by methane in the two different thickness preforms were simulated.The simulated results show that the sample density distribution after 120 h densification is well matched with the experimental results,which further validates the proposed models.