摘要
利用隶属函数表征了碳/碳(C/C)复合材料CVI工艺各主要影响因素,基于Matlab模糊逻辑工具箱,建立了C/C复合材料等温CVI工艺Mamdani模糊系统模型,分析了沉积温度、沉积时间、预制体纤维体积分数和前驱碳氢气体与稀释气体的比率对制件密度的影响。预制体纤维体积分数是直接影响材料的密度和其它性能的因素;CVI工艺受热解化学反应和前驱气体扩散两个主要过程的控制,沉积温度或前驱碳氢气体比率升高,能够加快热解化学反应速度,使沉积速率在沉积前期(t<300h)具有较高的值,但导致材料的密度梯度增大,使后期沉积极为困难。
A model of Mamdani fuzzy system for isothermal chemical vapor infiltration (CVI) process of C/C composites was established. The influences of processing parameters, such as infiltration temperature, time, fiber volume fraction, gas volume flow rate and hydrocarbon concentration, were analyzed. The fiber volume fraction of preforms has significant effects on the bulk density and other properties of C/C composites. CVI processes are mainly determined by the pyrolysis reaction and the transportation of gas precursor. When the infiltration temperature and the ratio of hydrocarbon are raised, the pyrolysis reaction rate would be enhanced; so that the infiltration rate will be kept higher when the time is less than 300 h. Unfortunately, this will increase the nonuniformity of densification resulting in higher density gradient which make further densification harder.
出处
《材料研究学报》
EI
CAS
CSCD
北大核心
2003年第4期375-379,共5页
Chinese Journal of Materials Research
基金
国家自然科学基金50072019
国家杰出青年科学基金50225210
