航空刹车用C/C复合材料坯体结构研究

Study on preform of carbon/carbon 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,对国外炭/炭刹车材料的部分力学性能和热导率进行了测试,并利用金相显微镜对其坯体结构进行了观察分析,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、气体扩散通造多、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700h CVD增密,小样密度可达1.81g/cm^3,大样密度达1.75g/cm^3,且能继续增密,与炭布叠层坯体相比,采用针刺整体毡可显著缩短CVD周期.

In order to find effective ways of lowering cost on carbon/carbon composites for aircraft brakes andimproving their performances, the mechanical performanes and thermal properties of such compositesfor abroad were partly determined and their performs were detected, then a kind of needle-punching feltwas fabricatec and densified by chemical vapor deposition (CVD), the results were compared with those ofcarbon cloth laminated. The following conclusions can be drawn: the ILSS (interlaminar shear strength)and thermal conductivity in the vertical direction of the C/C composites for aircraft brakes from abroad arehigher, and needle-punching felts tend to be used. Neede-punching felts are made up of inter-layerednon-woven cloth and chopped fiber web, which are needle-punched. The performs have the properties ofeven-distributed porosity, much mere diffusion path for gas and higher content of fibers in the Z direc-tion, which give better conditions for CVD. Densified for 700 h, the self-fabricated needled integratedfelts can get a density of 1 .81 g/cm^3 for small Sanoles (Ф_1 150 mm × Ф_2 40 mm × 22 nnn) and 1. 75 g/cm^3 for large ones (Ф_1 360 mm × Ф_2 155 mm × 22 mm) and can be densified continuously. Compared withcarbon cloth laminate, using needled felts can shorten the period of CVD greatly.