航空刹车用C/C复合材料坯体结构的研究

Study on Preform of C/C Composites for Aircraft Brakes

为了探索降低航空刹车用C/C复合材料成本、提高性能的有效方法 ,对现役国外航空刹车用C/C复合材料的部分力学性能和热导率进行测试 ,并利用金相显微镜对其坯体结构进行观察分析 ,在此基础上 ,自制了一种针刺整体毡 ,进行CVD增密 ,并与炭布叠层坯体的结果对比。结果表明 :国外航空刹车用C/C材料的层间剪切强度和垂直方向热导率比较高 ,坯体趋向于使用针刺毡 ;针刺整体毡由无纬布和网胎交替叠层 ,经针刺而成 ,这种结构具有孔隙分布均匀、气体扩散通道多、Z向纤维含量高的特点 ,为CVD增密创造了良好条件 ;自制针刺整体毡坯体经 70 0hCVD增密 ,小样密度可达 1.81g/cm3 ,大样密度达 1.75g/cm3 ,且能继续增密 ,与炭布叠层坯体相比 。

In order to find effective ways of lowering cost of C/C composites for aircraft brakes and improving their performances, some mechanical performances and thermal properties of foreign composites were measured and their preforms were detected. A kind of needle punching felt was fabricated and densified bychemical vapour deposition(CVD). The results obtained were compared with those of carbon cloth laminated preform. The following conclusions can be drawn: the ILSS(interlaminar shear strength) and thermal conductivity in the vertical direction of the foreign C/C composites for aircraft brakes are higher, and needle punching felts tend to be used. Needle puching felts are made up of inter layered non weft cloth and chopped fiber web, which are needle punched. The performs have the properties of even distributed porosity, much more diffusion paths for gas and higher content of fibers in the Z direction, which can give better conditions for CVD. Densified for 700 hours, the self fabricated needled integrated felts have a density of 1.81 g/cm 3 for small samples(Ф150 mm×Ф40 mm×22 mm) and 1.75 g/cm 3 for large ones (Ф360 mm×Ф155 mm×22 mm) and can be densified continuously. Compared with carbon cloth laminate, the period of CVD can be greatly shortened using needled felts.