航空刹车用CC复合材料的结构及其性能研究.docx

摘 要本文采用炭布叠层、CVD工艺制备出C／C复合材料，结合与俄罗斯合伙 研制的短纤维随机取向、CVD C／C复合材料及国外已用于飞机制动的同类材 料，以构造、石墨化度为主线，以航空刹车为运用背景，在研究了材料构造的 基本上，进一步研究了其物理性能、摩擦磨损性能、力学性能和热性能，用结构揭示了性能，并讨论了有关因素对这些性能的影响通过对比分析，明确了 适合于飞机刹车用C／C复合材料应具有的构造和性能，找出了自制材料与国外 材料的差别，并对产生这些差别的本质因素进行了分析，为进一步制备出性能 优良的航空刹车C／C复合材料指明了方向j(i)研究了C／C复合材料的偏振光显微构造及纤维分布、取向特点，获 得了有关材料的偏光构造及纤维分布的构造特点，明确了国外材料预成型体中 的纤维增强方式ii)研究了C／C复合材料的体积密度、石墨化度、微晶尺寸和硬度等重 要物理性能，找到了构造与这些性能之间的关联，讨论了有关因素对各项性能 的影响初次把XRD分峰软件运用于C／C复合材料石墨化度的测定中，并且 与前人不同，采用对(004)面衍射，一方面提高了测试精度，另一方面发现 了自制材料与国外材料在石墨化度问题上的本质不同，借助喇曼光谱，作了进 一步的研究，证明了XRD成果的可靠性。

iii)用惯性测功仪分别模拟了飞机在正常着陆、超载着陆和终结起飞条 件下的刹车过程，研究了C／C复合材料的摩擦磨损性能，明确了这种用途下材 料应具有的摩擦磨损性能特点进一步对体积密度、构造、石墨化度、纤维增 强方式、压力、能量、摩擦面温度、湿度等影响因素进行了研究与分析，提出 了合理的摩擦磨损机理，并用这一机理，结合外界影响因素较好地解释了制动 过程中摩擦磨损性能的变化iv)研究了C／C复合材料的力学性能，获得了合用于航空刹车C／C材料 应有的力学性能值范畴，讨论了体积密度、构造、石墨化度、纤维含量及其增 强方式对性能的影响，进一步研究了材料的断裂行为和韧性，拟定了不同构造 材料所相应的断裂模式 ’(v)研究并测定了C／C复合材料在两个方向上的导热系数，获得了可应 用于航空刹车C／C材料对导热性能的规定结合声子导热机理，讨论了体积密 度、构造、石墨化度、纤维增强方式和温度对材料导热系数的影响，并研究了 热解决温度对材料导热系数的影响，分析了自制材料导热系数低的本质因素f川核心词：C／C复合材料，构造彳／体积密度，石墨化度，摩擦磨损性能，力学性能，导热系数ABSTRACTWitll plain woven cloth of carbon yarns reinforced．isothermal CVI densified and with randomly chopped carbon fibre reinforced，thermal gradient CVI densified， two kinds of carbon—carbon composites have been successfully fabricated respectively．Combincd with the matedals having been used as brake for aeroplane，the physical and mechanical properties，the friction and weaL the therlTlalconductivity were studied respectively under也e background of airplane brakeapplication after the microstructure of these materials had been investgated．Theeffects of the microstructure．the degree of graphitization and other factors on廿1eseproperties were discussed．By comparing the results，the microstructure and the property of carbon—carbon composite sllitable for aeroplane brake were obtained．alSO di脏rences between the self-made materials and the foreign materials which has beenused on airplane were found．The essential causes which led to these diffefences werefurther analyzed in order to manufacture new carbon-carbon brake material with moreexcellent properties．(i)By studying the optcai micrograph under polarized light illumination埘th thecarbon-carbon composites，the corresponding micmstructure，fmre orientation anddistribution were obtained．alSO the fibre reinforce pattem in prefornl of the foreignmatedals were made clear．(ii)By studying the important physical properties which include bulk density, degree of graphifization．crystallite size and hardness witll the eriect of interrelated factors On it discussed．也e relationship between也e microstmctures and the properties was obtalned．For the first time，the X-ray difiraction separation software was adopted to measure the degree of graphitization．Tb be di丘brent from literature inwhich，the interlayer spacing，d 002，and apparent crystallite size，L。

were obtained from the(002)peak，the(004)plane Was selected here to be di衢acted in order to raise measurement precision．In this way,the essential difference on degree ofgraphitization between the self-made matedals and也e foreign matedals was found．Further investigation Was made by micro laser Raman spectroscopy to identify thereliability ofthe results obtained from廿le XRD．(iii)The衔ction and wear properties of carbon—carbon composites were studied by stimulating brake process under three different energy(service landing，maximum landhag design gross weight，rejeeted take·off)with inertia dynamometer,the suitableproperties for aircraft brake were obtained．11le effect of bulk density,microstructure．degree of graphitization，fibre reinforce pattem，pressure，energy,friction surfacetemperature and humidity on friction was further investigated respectvely and the·V’reasonable伍ction and weal"mechanism was posed．Combined with environmental influence factors，the variation of friction and weal"property during the brake process was well explmned．(iv)Mechanical properties of the carbon-carbon composites were studied and the value range appropriate for airplane brake was obtmned．The effect of bulk density, microstructure，degree of graphitizafion，fibre volume fraction and its reinforce pattern on the property was discussed．The fracture behavior and toughness of thecomposites were further studied with fracture modes of the materials with difierentmicrostructures analyzed．(v)Studied the thermal conductivities of the carbon—carbon composites with thevalUeS iIl two出reetions measured．the requirement for that suitable for aircraft brake was made clear．Combined with phonon heat conduct mechanism，the influence of bulk density,microstructure，degree of graphitization，fibre reinforce pattern and environmental temperature to thermal eonduetivity Was discussed with the effect of heat treatment on the propert。