C/C喉衬近净尺寸制备及性能

采用径向针刺工艺制备了近净尺寸针刺C/C喉衬预制体,通过热梯度CVI和树脂浸渍碳化复合工艺对预制体进行了致密,利用μ-CT、光学显微仪表征了C/C喉衬材料微观孔隙和热解碳织构,分析了喉衬材料的弯曲性能。结果表明,径向针刺过程形成的损伤型孔隙通道与碳源气体传输方向一致,提高了碳源气体传输效率,使径向针刺喉衬CVI增密效率比传统轴向针刺喉衬提高10.9%。预制体近净尺寸成型缩短了烧蚀区域碳源气体的渗透距离,喉衬材料烧蚀区域形成了高织构热解碳,有利于喉衬烧蚀性能的提高。径向针刺喉衬的轴向弯曲强度比轴向针刺喉衬提高150%。

Near net-shape fabrication and properties of C/C throat

The near net-shape carbon fiber throat preform was fabricated via radial needling technique,which was further densified by thermal gradient CVI combined with the resin impregnation and carbonization methods.The final product was made with a density of 1.84g/cm3 in the test.The microstructure of the micro-pores and the structure of the pyrocarbon were observed by the μ-CT and polarized light microscopy respectively,and bending property of C/C throat was determined.The results show that the insertion space of the needled process and the transportation of the hydrocarbon gas have the same path,which could enhance the transportation efficiency of the hydrocarbon gas in the CVI process.It shows that the densification rate is increased by 10.9％ compared with the traditional axial direction needling method.The near net-shape forming of the preform reduces the infiltration path of the hydrocarbon gas on the ablation area.It helps to form the high density pyrocarbon on the key area of the throat,which can enhance the anti-ablation properties of the throat material.In addition,the bending strength of the radial direction needled material reach 75 MPa,which is increased by 150％ compared with the axial direction needled material.