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飞机刹车用长寿命高摩擦特性炭/炭复合材料制备技术(英文)[刊,中]/苏君明,肖志超,刘勇琼,等//新型炭材料,2010,25(5):329～334以针刺炭纤维准三向结构整体毡为预制体,经丙烯气体狭缝定向流的"外热内冷"、"内热外冷"径向热梯度CVI工艺致密技术,优化组合的热解炭/树脂炭双元炭基体技术,通过调控高温处理技术等三大关键技术制备了A320系列飞机炭刹车盘材料。     

C/C复合材料中基体炭的微观结构表征

采用扫描电子显微镜、金相偏光显微镜对不同结构基体炭，包括热解炭、沥青炭、树脂炭进行形貌表征和分析。通过试验观察到热解炭的微观结构主要分为粗糙层结构、光滑层结构、过渡层结构和各向同性结构，热解炭表面为球冠形结构；沥青炭的主要形貌结构主要有镶嵌型结构，区域与镶嵌并存结构，区域与流线型并存结构，流线型结构；树脂碳的结构主要为表面光滑的块状结构。     

原位炭补强整体粘接处理对炭刹车盘材料性能的影响

采用原位炭补强整体粘接修复飞机炭刹车盘的方法,与国外常用的“二合一”铆接修复方法相比,不改变Dunlop炭刹车盘材料的摩擦特性,对母体材料的密度、硬度、表面孔率,经加工过的影响也不明显,但其导热系数比“二合一”铆接炭刹车盘材料提高了30％,改善了飞机炭刹车盘材料修复后的整体性,可靠性和安全性,是一种技术创新的修复方法,除用于B757-200飞机炭刹车盘材料的维修外,还用于其他型号飞机炭刹车盘材料的维修。     

不同炭基体对炭/炭复合材料力学性能的影响

结合化学气相沉积（CVD）和前驱体浸渍裂解工艺,分别以丙烯、糠酮树脂和煤沥青为前驱体制备了密度在1.85g/cm3以上的三维炭/炭（C/C）复合材料,对比研究了沥青炭、热解炭+沥青炭以及热解炭+树脂炭结构（分别为A、B、C组）的等三种不同炭基体C/C复合材料的增密效率与力学性能,采用排水法表征C/C复合材料的孔隙率及密度,利用扫描电镜进行炭基体的微观结构表征,采用万用电子力学试验机进行拉伸强度、压缩强度、剪切强度等力学性能表征。结果表明,在热解炭质量含量相同的前提下,树脂浸渍裂解增密速率低于沥青浸渍裂解工艺,树脂炭基体孔隙率低于沥青炭基体。不同炭基体结构的C/C复合材料力学性能次序为：热解炭+树脂炭双元炭基体最高,纯沥青炭基体次之,热解炭+沥青炭双元炭基体最低,分析原因为热解炭与树脂炭双元炭基体的界面结合强度高,而沥青炭为混乱无序碳结构,热解炭和沥青炭双元炭基体界面结合强度弱,因此力学强度最低。     

炭/炭复合材料化学液气相沉积致密化技术研究

介绍了炭/炭复合材料化学液气相沉积工艺的基本原理.化学液气相沉积工艺与热梯度化学气相沉积工艺在本质上是相同的,不同之处是化学液气相沉积用液态烃作前驱体,提高了原料的利用率,加快热解炭沉积的速率.研究了不同沉积温度对炭/炭复合材料微观组织结构的影响.采用偏光显微镜观察了材料的粗糙层、光滑层热解炭微观组织结构.研究发现用环己烷作前驱体当沉积温度为1 100℃时可以得到粗糙层结构的热解炭.     

A320系列飞机炭刹车盘钢夹结构的改进研究

本文通过对比分析几种常用的飞机炭刹车盘钢夹结构,提出了用于A320系列飞机炭刹车盘的改进钢夹结构,有效地减少了由于钢夹损坏造成未磨损到寿的炭刹车盘不能继续使用的情况,提高了炭刹车盘使用的可靠性.     

工艺参数对疏松热解炭微观结构的影响

以不同浓度的乙炔为碳源气体,在不同温度条件下,采用化学气相沉积的方法,在不同表面粗糙度的基体上沉积制备出各种疏松热解炭样品,用扫描电镜检测了疏松热解炭涂层的微观结构。结果表明:在1100~1550℃,随着沉积温度的升高,疏松热解炭颗粒尺寸逐渐增大,1400℃以后沉积的疏松热解炭颗粒较大;粗糙度较小时,不容易发现致密层,当粗糙度达到一定数值,会发现疏松热解炭内层致密外层疏松现象,并且观察发现,随着基体表面粗糙度的加大,致密层逐渐增厚;随着乙炔浓度的增加,疏松热解炭的颗粒尺寸逐渐减小。     

炭基体结构状态对C/C复合材料抗烧蚀性能的影响

碳基体在C／C复合材料的组成中占有很大的比重，因此炭基体不同的结构状态往往对C／C复合材料的各项性能有显著的影响。本文利用不同的原料和加工工艺制备出了三种具有不同炭基体的C／C复合材料，这三种碳基体分别是热解炭，沥青炭以及解热炭－树脂炭混合炭基体。对这三种材料多项性能的测试结果表明，炭基体的结构状态如石墨化度，炭片层结构的取向度的不同对C／C复合材料的各项性能均有显著的影响；基本趋势是C／C材料的石墨化度越高，材料的导电性能，导热性能以及抗烧蚀性能越好，压缩强度越低。三种炭基体中沥青炭基体沿纤维轴向的取向度最低，其抗烧蚀性能最差。     

纳米压痕技术测试纤维束内沥青炭和粗糙层热解炭的力学性能

为了研究纤维束内沥青炭和粗糙层热解炭的力学性能,以2.5D针刺炭毡为增强体,分别通过中温煤沥青浸渍炭化和化学气相沉积制备得到C/C复合材料。使用G200型纳米压痕仪对C/C复合材料纤维束内基体进行纳米压痕测试,采用连续刚度测试方法,利用Oliver和Pharr模型获得试样弹性模量随测试深度的变化,利用弹性模量和硬度两参数Weibull分布函数对纳米压痕测试结果进行统计分析。结果表明,沥青炭和粗糙层热解炭的弹性模量平均值分别为(14.92±2.02) GPa和(12.87±1.35)GPa;硬度的平均值分别为(0.64±0.14) GPa和(0.67±0.17) GPa。沥青炭和粗糙层热解炭的弹性模量的Weibull分布模数分别为8.60和9.18,弹性模量的特征值分别为15.63 GPa和13.40 GPa。     

热解炭微观结构对炭/炭复合材料力学性能的影响

以PAN基针刺纤维毡为基体,采用等温化学气相渗透技术,在温度1000℃、压力5.0~20.0 kPa条件下制备了2种具有不同微观结构热解炭的炭/炭复合材料,研究了其力学性能与热解炭微观结构的关系. 结果表明,压力8.0 kPa下得到的具有单一低织构热解炭的炭/炭复合材料的断裂强度较高,为86±3 MPa,热解炭与炭纤维间界面结合紧密,加载过程中二者同时断裂,呈现明显的脆性断裂行为;压力10.0~20.0 kPa下得到的具有中织构-高织构-中织构热解炭的炭/炭复合材料的断裂强度稍低,为82±4 MPa,加载过程中材料内部不同织构热解炭间多层次界面通过改变裂纹扩展路径而延缓其扩展速度,断口形貌呈现锯齿状,表现出假塑性断裂特征.     

Friction behaviors of carbon/carbon composites with different pyrolytic carbon textures

Friction and wear properties of carbon/carbon (C/C) composites with a smooth laminar (SL), a medium textured rough laminar (RL) and a high textured RL pyrolytic carbon texture were investigated with a home-made laboratory scale dynamometer to simulate airplane normal landing (NL), over landing (OL) and rejected take-off (RTO) conditions. The morphology of worn surfaces at different braking levels was observed with scanning electron microscopy. The results show that C/C composites with RL have nearly constant friction coefficients, stable friction curves and proper wear loss at different braking levels, while friction coefficients of C/C composites with SL pyrolytic carbon decrease intensely and their oxidation losses increase greatly under OL and RTO conditions. Therefore, C/C composites with a high and medium textured RL pyrolytic carbon may satisfy the requirements of aircraft brakes. The good friction and wear properties of C/C composites with RL are due to the properties of RL, which leads to a uniform friction film forming on the friction surface.     

增强树脂基无石棉闸瓦的摩擦性能分析

以矿用增强树脂基无石棉闸瓦工况条件及运行参数为背景,以酚醛树脂基复合材料闸瓦WSM–3为研究对象,选择名义接触压力P、滑动速度υ、接触面温度T为可调参数,考察三者与摩擦系数μ的关系。并通过3个可调参数的多种组合分析复合材料的摩擦学性能,实验结果表明单参数、双参数、三参数实验方法在分析摩擦系数变化的不同性质时各有利弊。建立组合参数与摩擦系数的关系对材料摩擦学设计具有重要意义,亦适用于其它材料的摩擦学性能实验。     

炭/炭复合材料的摩擦磨损性能及应用

论述了炭／炭复合材料的特点，结合该材料在飞机刹车盘中的具体应用，讨论了炭／炭复合材料在不同环境气氛下的摩擦磨损行为及其影响因素，并阐明了炭／炭复合材料的研究现状和尚需解决的问题。     

C/C刹车盘制备工艺的研究

选择整体针刺毡为预制体，致密化工艺采用气相沉积(CVD)，以天然气和丙烷的混合气体为原料，制备C／C刹车盘。其热解炭以粗糙体为主，摩擦曲线平稳，没有湿态衰减，沉积时间短。     

Development and tribological studies of a novel metal-ceramic hybrid brake disc

Ceramic matrix composite (CMC) friction materials show promising tribological properties. Typically, carbon ceramic brake discs consist of a C/SiC rotor which is joined to a brake disc bell. Within this work, a novel metal-ceramic hybrid brake disc, consisting of C/SiC friction segments which are mounted by screws onto an aluminum carrier body, was designed and investigated. A prototype was built which was tribologically tested with three different brake pad materials, LowMet reference, modified SF C/SiC as well as C/C. A constant starting sliding velocity of 20 m/s and braking pressures of 1, 2, and 3 MPa were investigated. To simulate emergency braking conditions 10 consecutive brake applications were carried out in close succession for each brake pad material and braking pressure. The C/C brake pad material showed the highest average coefficient of friction followed by the LowMet and C/SiC material. However, the wear rates of the C/C and LowMet material were orders of magnitude higher compared to the C/SiC material.     

混杂纤维增强酚醛闸片在提速列车上的应用研究

采用混杂纤维作增强材料并以改性酚醛树脂为基体制成提速列车用的制动闸片。在1∶1列车动力试验台上对闸片的应用特性进行了测试。试验结果表明，研制的制动闸片在紧急制动、常规制动、洒水制动、坡道调速制动和静摩擦情况下的摩擦性能均十分理想，而且摩擦系数的离散性很小。实验发现，摩擦工作面的成膜控制是解决制动闸片的速度敏感性和温度敏感性问题的关键。     

碳纤维增强PEEK复合材料的摩擦学性能研究

用磨损试验机对碳纤维增强聚醚醚酮（PEEK）复合材料进行室温干滑动磨损试验。考察了碳纤维的含量，石墨润滑剂，对靡时间及载荷对材料靡损量及摩擦系数的影响，并用电子显微镜对其磨损表面进行了观察与分析，同时对材料的磨损机理进行了探讨，研究结果表明，随着载荷的升高和对磨时间的延长，材料的摩擦系数逐渐降低并趋于稳定，磨损量呈上升趋势，加入碳纤维可以明显地降低材料的摩擦系数和磨损量，当碳纤维含量为5％－10％时复合材料的摩擦系数和磨损量最低；加入适量固体石墨可进一步降低复合材料的摩擦系数和磨损量。     

碳/碳化硅复合材料刹车盘/片热应力场分析

采用有限元方法分析二维正交碳纤维增强碳化硅(C/SiC)复合材料制成的汽车刹车盘/片在刹车过程中引起的非线性热力耦合行为,主要研究在强制对流和热辐射作用下刹车结构的温度变化,讨论不同材料属性对刹车温度场的影响以及在温度场和膨胀系数耦合下C/SiC刹车盘/片中热应力和形变情况。数值结果表明:在双重散热条件下需要更多时间用于降温,而垂直于刹车面的热导率分量对温度传导或者降温影响较大;对于C/SiC刹车盘/片每一次刹车行为等效于一次热应力的加载和卸载,而每次产生的热应力可能突破C/SiC的极限弹性强度引起的残余塑性形变,而这种不断累积的残余效果继而引起C/SiC刹车盘/片失效。     

Effect of heat treatment on the tribological behavior of 2D carbon/carbon composites

The effect of high temperature heat treatment on the tribological behavior of carbon/carbon (C/C) composites has been investigated. C/C composite preforms were made from 1K PAN plain carbon cloth, and densified using rapid directional diffusion (RDD) CVI processes. Four specimens treated at 1800, 1800+2000, 2000, and 2300 °C, respectively, were prepared. A ring-on-ring specimen configuration was used to simulate aircraft brakes. The brake initial angular velocity ranged from 1800 to 7500 rpm (6.2-26.0 m s⁻¹ average linear sliding velocity). The specific pressure and moment of inertia were 392-784 kPa and 0.25-0.31 kg m², respectively (1.9-42.3 MJ m⁻² kinetic energy loading per unit friction surface area). The results showed that the stability of the brake moment-time curves increased with increasing heat treatment temperature (HTT) for the four composites, and those treated at 2300 °C possessed the lowest initial brake moment peak ratio values (from 1.1 to 1.3). The high degree of graphitization and low shear forces of the matrix carbon resulting from the high HTT could allow friction films to develop and reduce those values under the present brake conditions. The friction coefficients of four RDD CVI C/C composites decreased with an increase in specific pressure. The resulting changes in the friction coefficient of the four composites due to the specific pressure changes have basically nothing to do with the interface temperature under those conditions. According to the practical brake conditions, the friction properties of RDD CVD C/C composites could be improved by regulating the structure of the brake discs, changing the specific pressure exerted on the discs and the heat treatment. The linear wear rates of the four materials increased with increasing HTT. The composites treated at 2000 °C had both high enough friction coefficients and the lower linear wear rates. The different heat treatment methods at 2000 °C had no obvious effect on the friction and wear properties of RDD CVI C/C composites.