基于ABAQUS不同刀具对碳纤维复合材料的钻孔研究

利用ABAQUS有限元模拟分析软件,模拟不同钻头在不同切削参数下钻削加工碳纤维增强树脂复合材料(CFPR)的钻孔过程,得到了钻孔过程中出现的最大轴向力。通过分析对比,得出不同参数与刀具对轴向力的影响规律,为加工该类复合材料提供了一定的理论数据。     

不同刹车压力下C/C复合材料的摩擦性能与摩擦面研究

采用MM-1000型摩擦磨损试验机对以光滑层、粗糙层为基体炭的2种C/C复合材料在不同刹车压力下的摩擦磨损性能进行了测试。借助微区拉曼光谱和扫描电镜对其摩擦表面的石墨化度与形貌进行了分析。结果表明：以粗糙层为基体炭的C/C复合材料比以光滑层为基体炭的C/C复合材料有更优异的摩擦压力或温度特性。微区拉曼光谱检测证实在摩擦面上粗糙层基体炭相对光滑层基体炭更易变形,所以以粗糙层为基体炭的C/C复合材料的摩擦面在刹车压力达到0.59 MPa时便能形成较厚的摩擦膜,故其摩擦因数能在较高刹车压力下（1.05-1.82 MPa）保持较高的稳定值（0.31）,且磨损适当;而光滑层基体炭C/C复合材料需在刹车压力超过0.82 MPa时摩擦面才能形成较薄的摩擦膜,并且由于其导热系数低,高压刹车时摩擦表面氧化严重,所以高压刹车时其摩擦因数衰减大,线性磨损率大,尤其是质量损失急剧升高。     

沥青基碳/碳复合材料的弯曲性能

采用三点弯曲法测试了单向和三维四向碳纤维增强的两种沥青基碳/碳(C/C)复合材料(1D-C/C和3D-C/C)在室温及1 800℃高温时的弯曲性能,分析了增强体结构、温度对C/C复合材料弯曲性能的影响,并探讨了其弯曲断裂时的界面机制。结果表明:3D-C/C的弯曲模量高于1D-C/C的,但其抗弯强度却明显低于1D-C/C的;1D-C/C的弯曲断裂呈脆性断裂,而3D-C/C的弯曲断裂则表现出明显的假塑性特征;对同一种增强体结构的沥青基C/C复合材料,在1 800℃时的弯曲性能高于其在室温时的。     

碳/碳复合材料基体上羟基磷灰石涂层的体外生物活性

通过分析碳/碳复合材料表面等离子喷涂羟基磷灰石(简称HA)涂层在模拟体液中浸泡后的钙离子浓度和pH值的变化,涂层表面沉积物的微观结构、相组成和钙、磷原子数比,研究了该涂层的体外生物活性。结果表明:随着浸泡时间的延长,浸泡液的钙离子浓度降低,pH值升高,涂层表面的CaO完全溶解,α-TCP和β-TCP轻微溶解;涂层表面的沉积物主要是晶相HA,涂层具有良好的体外生物活性。     

Effect of Resin-Derived Carbon on the Friction Behavior of Carbon/Carbon Composites

Three different C/C composites with rough laminar (RL) pyrocarbon, RL pyrocarbon with added resin-derived carbon, and pure resin-derived carbon have been evaluated and tested for friction performance. A laboratory dynamometer was used to simulate different braking speeds utilizing a single stator and rotor pair. The morphologies and microstructures of the raw materials, wear surfaces, and wear debris at different braking levels were observed by polarized light microscopy, scanning electron microscopy, and transmission electron microscopy. The results have shown that the friction coefficients of the three C/C composites display the same characteristics with increasing braking speed. They increased to a maximum value at medium braking speed and thereafter decreased with increasing braking speed, and their mean values under the same braking conditions were similar. The C/C composite with pure resin-derived carbon showed the highest loss due to wear under all conditions, while the C/C composite with the RL pyrocarbon showed the lowest loss. Resin-derived carbon in C/C composites does not have a significant effect on the friction coefficient, but the wear rate increases greatly with increasing resin-derived carbon content. Wear debris is composed of flocculent particles with polycrystalline structure, along with the matrix carbon, which is worn off directly from the composites.     

浸锑石墨摩擦磨损特性研究

为使石墨产品能够应用于高温及重载条件下且能表现出良好的的耐磨性和自润滑性,使用机械加压工艺将熔融锑浸入石墨坯料气孔中制得浸锑石墨复合材料,并对浸渍前后样品的微观结构、摩擦磨损性能进行了研究,评价了浸锑石墨浸渍后磨损量及润滑性能的变化。结果表明,浸锑后磨损量减少96.6%,摩擦因数降低了45%,证明浸锑后石墨材料的摩擦磨损性能有所提高。     

Tribological and Mechanical Behaviour of Epoxy/Nanoclay Composites

Due to the nature and availability of nanoclay material, its application as reinforcement of composite materials is well justified. In this work, organo-montmorillonite filler with an epoxy resin matrix was characterised, regarding its mechanical and tribological behaviour. The influence of water ageing was analysed concerning its mechanical properties. Tribological tests were performed in dry and water lubricated environments. The mechanical properties of both the epoxy resin and composite specimens tend to decrease with water ageing. The negative influence of particle agglomeration was verified in the mechanical and tribological properties, especially with high content of filler material.     

液相气化法制备碳/碳复合材料工艺研究

探索了一种快速制备碳 /碳复合材料的新工艺——液相气化 CVI法。该工艺在沉积温度 80 0～ 14 0 0℃内 ,沉积时间 3h,多孔材料表观密度可达到 1.6 8g/ cm3,致密化速率达到 1.4～ 1.7mm/ h,致密化效率比报道的常规等温 CVI工艺要快 2个数量级以上。本文根据多孔介质传质传热学理论初步分析了该工艺快速致密的根本原因 ,采用偏光显微镜及扫描电镜观察了材料的微观组织结构及热解碳的生长特征 ,并测定了材料的表观密度及力学性能     

预制体添加BN对炭/炭复合材料性能的影响

在炭纤维预制体中添加六方氮化硼(h-BN),采用等温化学气相渗透(CVI)和超高压沥青浸渍/碳化混合工艺制备了炭/炭(C/C)复合材料。研究了材料的组织结构和力学性能,采用XD-MSM定转速摩擦试验机对材料的摩擦磨损性能进行了测试;分析了h-BN含量对摩擦磨损性能的影响。实验表明:预制体添加h-BN可以明显降低材料的摩擦系数,稳定材料的摩擦磨损性能。其中以9wt%时,材料的摩擦磨损性能最佳。     

密度梯度碳/碳复合材料的制备及性能

采用强制流动热梯度化学气相渗透法在1000～1 250℃制备了密度梯度碳/碳复合材料;借助三点弯曲试验和激光闪烁法测定了复合材料的弯曲性能与导热系数,用偏光显微镜及扫描电子显微镜观察了基体热解碳的组织结构及断口形貌。结果表明:该复合材料上层的最大密度为1.65g·cm~(-3),下层的最小密度为1.10g·cm~(-3),具有明显的密度梯度;复合材料的密度越大,抗弯强度越高;其导热系数也随密度的增加而增大;沉积温度是影响基体热解碳组织的主要因素,高温有利于粗糙层热解碳的生成,而低温有利于光滑层热解碳的生成。     

送粉方式对碳/碳基体上等离子喷涂羟基磷灰石涂层的影响

采用等离子喷涂技术在碳／碳复合材料上制备了羟基磷灰石(HA)涂层，采用扫描电镜、X射线衍射仪、电子探针和电子拉伸机等研究了送粉方式对HA涂层的组织与性能的影响。结果表明：内送粉方式下制得的HA涂层，颗粒熔化程度较高，涂层的晶相含量较低；40kW的喷涂功率和外送粉方式下制得的HA涂层与碳／碳基体的抗剪强度最高；但HA涂层与碳／碳基体之间仍属于机械结合。     

复合铸造法制备纳米碳管增强镁基复合材料的研究

采用复合铸造的方法制备了碳纳米管(CNTs)增强镁基复合材料；对其力学性能进行了测试，并对显微组织进行了观察和分析。用透射电镜(TEM)和能谱(EDS)方法对CNTs涂覆层的界面结构和成分进行分析，探讨了CNTS对镁基复合材料的增强机理及作用机制。试验结果表明：加入CNTs后，复合材料的抗拉强度比基体最高可提高150％以上，延伸率最高可提高30％以上，平均弹性模量可增加近80％，硬度可升高6HB；采用化学镀镍方法可在CNTs表面获得均匀的涂覆层，改善CNTs与基体的润湿和结合状况，提高CNTs对镁基材料的增强效果。CNTs对镁基材料具有较好的增强效果，能明显细化晶粒组织．促使复合材料的位错密度增加，大幅度提高复合材料的抗拉强度、延伸率、硬度和平均弹性模量。但在本文试验条件下，CNTs的加入量不能太高，否则，因CNTS难以分散而使复合材料的性能大幅下降。     

包埋工艺参数对碳/碳复合材料表面SiC涂层致密性的影响

采用包埋法在碳/碳(C/C)复合材料表面制备出不同致密度的SiC涂层,用正交试验法系统研究了包埋温度(A)、包埋时间(B)、烧结助剂Ⅰ含量(C)、烧结助剂Ⅱ含量(D)、硅含量(E)等工艺参数对SiC涂层抗氧化性能(用抗氧化性能表征涂层的致密性)的影响.结果表明:研究的包埋工艺参数对SiC涂层抗氧化性能(致密性)影响的显著性从大到小依次为A,C,E,D,B;在A1B1C1DE1工艺条件下所得的SiC涂层最疏松;通过改进参数,在A3B2C4D2E4工艺条件下所得的SiC涂层最致密,该涂层可在1 500℃空气中提供10 h以上的抗氧化保护.     

热梯度化学气相沉积工艺制备炭/炭复合材料

阐明了热梯度化学气相沉积工艺(CVI)的优越性和用于制备炭／炭复合材料的热梯度化学气相沉积工艺原理；壁冷式热梯度CVI工艺克服了等温化学气相沉积易形成闭孔的缺陷，实现了快速均匀致密化；热梯度CVI工艺设备简单且安全系数高，所制备的炭／炭复合材料密度均匀性好，通过控制工艺参数，利用热梯度CVI工艺可以制备不同微观组织结构的热解炭。     

聚氨酯/碳纳米管复合材料的摩擦性能

采用溶液共混法制备聚氨酯/碳纳米管复合材料,探讨碳纳米管含量和超声分散时间对聚氨酯/碳纳米管复合材料摩擦性能的影响。结果表明:随着碳纳米管含量的增加,聚氨酯/碳纳米管复合材料的摩擦因数逐渐降低,随着载荷的增大,摩擦因数有所减小;超声分散时间对聚氨酯/碳纳米管复合材料摩擦性能影响不大;碳纳米管具有较好的润滑性质,可以降低聚氨酯/碳纳米管复合材料的摩擦因数,改善聚氨酯的摩擦性能。     

喷涂功率对碳/碳复合材料表面羟基磷灰石涂层抗剪强度的影响

采用等离子喷涂技术在碳／碳复合材料表面制备了羟基磷灰石（HA）涂层,采用自制装置测定了不同喷涂功率下涂层与基体的抗剪强度,采用扫描电镜观察了涂层表面、横截面和剪切断裂表面的微观形貌,并分析了涂层与基体的剪切断裂失效形式。结果表明：在40kw喷涂功率下,涂层与基体的抗剪强度最高,约为10MPa,其剪切断裂失效方式主要为涂层内部失效。     

Impact Abrasive Wear Response of Carbon/Carbon Composites at Elevated Temperatures

Three types of carbon/carbon composites were fabricated using pitch as matrix material. Performance of these composites was evaluated under continuous impact abrasion tests (CIAT). Towards this purpose, a novel testing equipment was designed and developed at AC²T. Tests were carried out at room temperature and 500 °C. The angle of impact was chosen to be 45° and 90°. Analysis of tribological performance was carried out by mass loss. Characterization of the worn surface was done by means of scanning electron microscopy (SEM) and optical 3D profilometry. In this work, it was shown that wear rates are higher for 45° impact angle compared to 90° for all composites investigated. Fibre debonding and fibre pull out was observed to be the dominating wear mechanisms for these composites during CIAT procedure under normal impact abrasion. Removal of chunk of material contributes to wear under oblique impact abrasion.     

阳极氧化对碳/环氧复合材料力学性能的影响

利用真空浸渍法制得碳纤维增强环氧复合材料,研究了阳极氧化处理前后碳纤维表面状态的变化及表面处理对复合材料力学性能的影响。结果表明：适当的阳极氧化处理使复合材料的弯曲和剪切性能有很大改善,但冲击性能有所降低。     

High-Temperature Protective Coatings on Carbon Composites

Russian Engineering Research - Research on high-temperature coatings for the protection of heat-proof carbon composites from oxidation and ablation in high-speed high-enthalpy fluxes of...     

类金刚石表面改性C/C复合材料的摩擦磨损性能

采用等离子体增强化学气相沉积法在C/C复合材料基底表面制备了不同厚度的类金刚石（DLC）表面改性膜;用球-盘对磨的方式测试了C/C复合材料基底和DLC膜在干态下的摩擦磨损性能。结果表明:制备的表面改性膜具有典型的DLC结构特征,均匀致密;随着沉积时间的延长,DLC膜厚度逐渐增大,膜基结合强度依次减小;C/C复合材料基底的平均摩擦因数为0.285 8,磨损率约为1.6×10^-4mm³·N^-1·m^-1,表面改性膜的摩擦因数较基底有较大程度的降低,在0.08～0.27之间,磨损率也降低了1～2个数量级,且沉积时间越长其摩擦因数越小、磨损率越低。