Gr（C）纤维增强镁基复合材料的界面结构

采用真空—压力浸渗工艺制备Ｇｒ（Ｃ）／Ｍｇ复合材料，Ｇｒ／Ｍｇ材料界面上无化学反应迹象，有析出物γ相（Ｍｇ１７Ａｌ１２），该析出物形状、大小与制备工艺条件，主要是纤维预制件温度有关。Ｃ／Ｍｇ复合材料界面Ａｌ含量较基体高出２倍多，文中分析了可能的原因     

铝—石墨界面反应对石墨,碳化硅混杂增强铝基复合材料摩 …

研究了石墨（Ｇｒ）－铝界面反应对Ｇｒ,碳化硅（ＳｉＣ）混杂增强铝基复合材料（Ｃｒ＋ＳｉＣ／Ａｌ摩擦磨损性能的影响。在６３０℃下对ＳｉＣＡｌ和混杂复材料分别加热保温了４,８,１２,１６ｈ。硬度试验和透射电镜分析说明,随热处理时间的延长,Ｇｒ－Ａｌ界面反应物增加,而ＳｉＣ－Ａｌ几乎没有发生界面反应。用热处理后的混杂复合材料试样进行了干磨损试验。结果透明,随着热处理时间的延长,混杂复合材料摩擦系数升高,     

反应生成Al2O3（p）／Al—Cu复合材料的研究

通过对ＣｕＯ／Ａｌ体系反应过程的研究，采用反应生成方法制备了Ａｌ２Ｏ３（ｐ）／Ａｌ－Ｃｕ复合材料，并对Ａｌ２Ｏ３颗粒在Ａｌ２Ｏ３（ｐ）／Ａｌ－Ｃｕ复合材料中的分散过程做了分析，得出了制备这种复合材料的工艺条件。     

喷射沉积Al-5.5Cu/TiAl3自生复合材料的微观组织及界面结构

采用喷射沉积工艺制备了Ａｌ－５．５Ｃｕ／ＴｉＡｌ３自生复合材料,并对该材料的微观组织及界面结构进行了研究。观察表明ＴｉＡｌ３与α－Ａｌ基体之间存在（０２０）Ａｌ／／（００２）ＴｉＡｌ３,［００１］Ａｌ／／［＾１１０］ＴｉＡｌ３的位向关系,力学性能测试结果表明喷射沉积Ａｌ－５．５Ｃｕ／ＴｉＡｌ３自生复合材料的抗拉强度较铸态的抗拉强度提高约１２％,延伸率提高４５０％,耐磨性则提高１５０％。     

加压浸渗工艺制备CF＼Al复合材料的研究

对加压浸渗工艺制备ＣＦ／Ａｌ复合材料进行了探讨，通过选择合适的工艺参数进行试验，获得了具有良好复合效果的ＣＦ／Ａｌ复合材料，在此基础上，进一步对ＣＦ／Ａｌ复合材料的显微组织，力学性能的断裂特征进行了研究。     

Al／TiC复合材料铸态组织和性能的研究

利用反应合成法制备了ＴｉＣ，并通过扫描电子显微镜（ＳＥＭ）和Ｘ射线衍射仪（ＸＲＤ）研究了反应合成ＴｉＣ的稳定性。结果表明：反应合成的ＴｉＣ具有亚微米尺寸，在Ａｌ液中具有良好的稳定性。另外，研究了不同ＴｉＣ含量的Ａｌ／ＴｉＣ复合材料的铸态组织和力学性能。结果表明：Ａｌ／ＴｉＣ复合材料随着ＴｉＣ含量的增加，铸态组织变得愈来愈细小，ＴｉＣ分布愈来愈均匀，而且材料的力学性能较纯Ａｌ基体有很大的提高。ＳＥＭ观察表明材料为韧断。     

石墨纤维增强Al基复合材料界面反应机制研究

本文利用透射电子显微镜（ＴＥＭ）对不同条件下形成的石墨长纤维增强Ａｌ—Ｔｉ（０．３５ａｔ—％）基复合材料的界面微观结构进行了比较研究，用高分辨透时电子显微术研究了Ａｌ＿４Ｃ＿３的生长规律，结果表明Ａｌ＿４Ｃ＿３顶端与Ａｌ基体间的界面粗糙，其生长机制为连续生长，Ａｌ＿４Ｃ＿３的（０００１）面与Ａｌ基体的界面光滑，其生长机制为沿面生长．两种生长机制在不同的生长驱动力作用下，具有不同的相对生长速率。因此在不同的材料制备工艺条下，Ａｌ＿４Ｃ＿３的形态也表现出不同的特点。讨论了纤维分布情况对界面微观结构的影响，认为适当降低纤维体积含量对进一步改善复合材料性能有利。     

石墨纤维增强Al基复合材料界面反应机制研究

本文利用透射电子显微镜（ＴＥＭ）对不同条件下形成的石墨长纤维增强Ａｌ－Ｔｉ（０．３５ａｔ－％）基复合材料的界面微观结构进行了比较研究，用高分辨透射电子显微术研究了Ａｌ４Ｃ３的生长规律。结果表明Ａｌ４Ｃ３顶端与Ａｌ基体间的界面粗糙，其生长机制为连续生长。Ａｌ４Ｃ３的（０００１）面与Ａｌ基面光滑，其生长机制为沿面生长。两种生长机制在不同的生长驱力作用下，具有不同的相对生长速率。因此在不同的材料制备工艺     

Ti—Al—Ga系及Ti—Al—Nb—Cr系α（α2）／γ相平衡的研究

利用电子探针微区成分分析测定了Ｔｉ－Ａｌ－Ｇａ系，Ｔｉ－Ａｌ－Ｎｂ－Ｃｒ系低Ｇａ，低Ｎｂ和低Ｃｒ部分的α（α２）／γ相平衡成分，推得了合金元素Ｇａ，Ｎｂ和Ｃｒ在α（α２）／γ平衡相中的成分分配比Ｋ＾（呔２）／γｉ，并利用分配比方程计算出Ｇａ，Ｎｂ和Ｃｒ在不同温度下的γ相的稳定化参数Δ＾＊Ｇ＾α（α２）→γｉ。结果表明，Ｇａ，Ｎｂ为γ相稳定化元素，Ｃｒ为α相稳定化元素。     

Ti－Al－Ga系及Ti－Al－Nb－Cr系α（α_2）／γ相平衡的研究

利用电子探针微区成分分析测定了Ｔｉ—Ａｌ—Ｇａ系，Ｔｉ—Ａｌ—Ｎｂ—Ｃｒ系低Ｇａ，低Ｎｂ和低Ｃｒ部分的α（α_２）／γ相平衡成分，推得了合金元素Ｇａ，Ｎｂ和Ｃｒ在α（α_２）／γ平衡相中的成分分配比Ｋ并利用分配比方程计算出了Ｇａ，Ｎｂ和Ｃｒ在不同温度下的γ相的稳定化参数结果表明，Ｇａ，Ｎｂ为γ相稳定化元素，Ｃｒ为α相稳定化元素．     

碳纤维含量对Cf/ZL109复合材料常温拉伸性能的影响

采用液态模锻法制备出单一碳纤维增强ZL109复合材料,并研究碳纤维含量对复合材料常温拉伸性能的影响。结果表明,碳纤维的加入对ZL109的常温抗拉强度是不利的,这主要与纤维与基体的界面、纤维取向等有关;但随着碳纤维体积百分数的增加复合材料的强度略有提高,这说明碳纤维在一定程度上起到了承载作用。     

Effect of stress level on fatigue behavior of 2D C/C composites

Laminated carbon fiber clothes were infiltrated to prepare carbon fiber reinforced pyrolytic carbon (C/C) using isothermal chemical vapor infiltration (CVI). The bending fatigue behavior of the infiltrated C/C composites was tested under two different stress levels. The residual strength and modulus of all fatigued samples were tested to investigate the effect of maximum stress level on fatigue behavior of C/C composites. The microstructure and damage mechanism were also investigated. The results showed that the residual strength and modulus of fatigued samples were improved. High stress level is more effective to increase the modulus. And for the increase of flexural strength, high stress level is more effective only in low cycles. The fatigue loading weakens the bonding between the matrix and fiber, and then affects the damage propagation pathway, and increases the energy consumption. So the properties of C/C composites are improved.     

Densification Behavior and Performances of C/C Composites Derived from Various Carbon Matrix Precursors

Three types of carbon/carbon (C/C) composites were manufactured by densifying the needled carbon fiber preform through resin and pitch impregnation/carbonization repeatedly, as well as propylene pyrolysis by chemical vapor infiltration plus carbonization after the resin impregnation/carbonization. The densification behavior and performances (involving electric, thermal, and mechanical properties, as well as impurity) of the C/C composites were investigated systematically. The results show that besides the processing and testing conditions, the electric resistivity, thermal conductivity (TC), coefficient of thermal expansion (CTE), strength, and fracture, as well as impurity content and composition of the C/C composites were closely related to the fiber orientation, interfacial bonding between carbon fiber and carbon matrix, material characteristics of the three precursors and the resulting matrix carbons. In particular, the resin-carbon matrix C/C (RC/C) composites had the highest electric resistivity, tensile, and flexural strength, as well as impurity content. Meanwhile, the pitch-carbon matrix C/C (PC/C) composites possessed the highest TC and CTE in the parallel and vertical direction. And most of the performances of pyro-carbon/resin carbon matrix C/C composites were between those of the RC/C and PC/C composites except the impurity content.     

低压浸渗法制备Gr（C）／Mg复合材料

对用低压浸渗法制备石墨（碳）长纤维镁基复合材料进行了研究。结果表明，制备工艺条件对复合状况、界面反应及复合材料性能均有明显影响。通过纤维表面ＳｉＯ２涂层处理和优化浸渗工艺，可成功地制备出高性能的复合材料，拉伸断裂强度可达５０９ＭＰａ，模量亦可达１４２ＧＰａ。     

PIP工艺制备2D C/SiC复合材料Z-向穿刺工艺

针对2D C/SiC复合材料存在碳布层间缺乏纤维增强,层间结合较差的问题,提出通过Z-向穿刺工艺提高碳布层间结合,克服材料使用时可靠性不高的问题,并比较了穿刺工艺对复合材料微观结构和力学性能的影响.结果表明,通过Z-向穿刺工艺制得试样2D C/SiC-Z_(pin)的弯曲强度、弯曲模量和剪切强度分别为247.8 MPa、37.8 GPa和32.1 MPa,而未穿刺试样2D C/SiC的弯曲强度、弯曲模量和剪切强度分别只有219.3 MPa、34.4 GPa和23.3 MPa,由此可见,采用Z-向穿刺工艺能明显提高复合材料的力学性能.微观结构分析认为,试样力学性能提高的根本原因在于采用Z-向穿刺纤维加强了碳布层间结合,使材料具有较好的整体性,克服了复合材料层间结合较弱对力学性能带来的不利影响.     

Flexural destructive process of unidirectional carbon/carbon composites reinforced with in situ grown carbon nanofibers

Unidirectional carbon/carbon (C/C) composites modified with in situ grown carbon nanofibers (CNFs) were prepared by catalysis chemical vapor deposition. The effect of in situ grown CNFs on the flexural properties of the C/C composites was investigated by detailed analyses of destructive process. The results show that there is a sharp increase in the flexural load-displacement curve in the axial direction of the CNF-C/C composites, followed by a serrated yielding phenomenon similar to the plastic materials. The failure mode of the C/C composites modified with in situ grown CNFs is changed from the pull-out of single fiber to the breaking of fiber bundles. The existence of interfacial layer composed by middle-textured pyrocarbon, CNFs and high-textured pyrocarbon can block the crack propagation and change the propagation direction of the main crack, which leads to the higher flexural strength and modulus of C/C composites.     

Tensile Properties of Polyimide Composites Incorporating Carbon Nanotubes-Grafted and Polyimide-Coated Carbon Fibers

The tensile properties and fracture behavior of polyimide composite bundles incorporating carbon nanotubes-grafted (CNT-grafted) and polyimide-coated (PI-coated) high-tensile-strength polyacrylonitrile (PAN)-based (T1000GB), and high-modulus pitch-based (K13D) carbon fibers were investigated. The CNT were grown on the surface of the carbon fibers by chemical vapor deposition. The pyromellitic dianhydride/4,4′-oxydianiline PI nanolayer coating was deposited on the surface of the carbon fiber by high-temperature vapor deposition polymerization. The results clearly demonstrate that CNT grafting and PI coating were effective for improving the Weibull modulus of T1000GB PAN-based and K13D pitch-based carbon fiber bundle composites. In addition, the average tensile strength of the PI-coated T1000GB carbon fiber bundle composites was also higher than that of the as-received carbon fiber bundle composites, while the average tensile strength of the CNT-grafted T1000GB, K13D, and the PI-coated K13D carbon fiber bundle composites was similar to that of the as-received carbon fiber bundle composites.     

The reinforcing mechanism of carbon fiber in composite adhesive for bonding carbon/carbon composites

A carbon fiber reinforced adhesive was developed for bonding carbon/carbon composites. The Weibull distribution method was used to analyze the bonding strength data, and the results showed that when the volume fraction of carbon fiber was 6 vol.%, the Weibull modulus was 42.9393 and the bonding strength of the adhesive was 11.3763 MPa. A model was proposed to explain the reinforcement of carbon fiber, and it was found that the strength of adhesive was a cubic function of the volume fraction of carbon fiber, and the function model was consistent with the Weibull data. We investigated that the carbon fiber could bridge adhesive matrix as a bridging effect for releasing the residual stress and inhibiting the extension of micro-crack.     

中间相沥青基炭/炭复合材料的微观结构与力学性能

借助偏光显微镜、扫描电镜、透射电镜以及力学性能测试研究了微观结构对中间相沥青基炭/炭复合材料力学性能的影响.结果表明基体炭在偏光显微镜下呈现出光学各向异性,在SEM和TEM下呈片层条带状结构.基体炭与纤维之间的界面不连续,为"裂纹型"界面.材料受载破坏时裂纹通过改变扩展路径而延缓其扩展速度,在纤维-基体界面处以及基体炭层片之间引起滑移,在断口形貌上体现出断裂台阶适中且与纤维拔出交替进行,表现出韧性破坏的断裂特征.材料具有较高的力学性能,抗弯强度达到257MPa.     

SiC纤维表面去碳处理对PIP-SiCf/SiC复合材料力学性能以及界面影响

采用强度测试、SEM、HRTEM等分析测试手段对纤维表面去碳前后SiC纤维强度、复合材料力学性能、纤维表面形貌、复合材料断口形貌以及复合材料界面特征进行分析表征.结果表明,去碳处理后,纤维表面的固有缺陷暴露出来,纤维强度下降约15%,但由其制备的复合材料强度下降只有原纤维制备复合材料的1/6;复合材料断口非常平整,纤维...