三维四向碳/碳预制件微孔板压实致密关键技术

为解决手工编织三维四向碳/碳复合材料预制件层间致密不一致的问题,基于预制件成型技术,建立碳纤维铺放高度与纤维体积含量映射关系,设计等距密排微孔板并提出适用于微孔板的加工工艺;同时为保证预制件压实致密过程中纤维流动性好,采用纤维压缩理论,对等距密排微孔板结构进行优化以降低预制件孔隙率。基于位移-压力双闭环控制策略,研制数字化压实装置,实现预制件密度在线动态调控与无损压纱,保证层间密度一致。为验证压实致密关键技术可行性,进行等距密排微孔板压实实验并对预制件进行形貌观测,结果显示采用优化后等距密排微孔板压实的预制件均匀性更好,较优化前等距密排微孔板压实的预制件孔隙率降低50%。

Key technology for compaction and densification of micro-porous plates made from 3-D four-directional carbon/carbon preforms

Aiming at the inconsistent density between layers of hand-woven 3-D four-directional carbon/carbon composite preforms, the mapping relationship between carbon fiber laying height and fiber volume content were established based on the prefabricated parts forming technology. Equal distance and density micro-porous plates were designed, and processing technique suitable for micro-porous plates was established to ensure uniform density of the preforms. In order to ensure good fiber fluidity during the compaction and densification process of the preforms, the fiber compression theory was applied and the optimization of the structure for equal-distance and density micro-porous plates was carried to reduce the porosity of the preform. Based on the control strategy of displacements-pressure double closed loop, a digital compaction device was developed for on-line dynamic control of the preform density and nondestructive compaction to ensure the uniform density between the preform layers. Compaction experiments of equal-distance and density micro-porous plates were carried out to verify the feasibility of the key technology of compaction and densification process and the preforms were examined with an industrial microscope. The results show that the uniformity of preforms compacted by the optimized equal-distance and density micro-porous plates is better, with the preform porosity reduced by 50% compared to the non-optimized preforms.