材料期刊网，材料期刊，材料类期刊，材料期刊投稿

陶瓷材料在热冲击荷载作用下的典型破坏模式是裂纹的起始和扩展.当高温的材料或构件突然处于低温环境时,裂纹将由材料或构件的表面开始产生和发展.因此,材料表面及其表面附近的材料微结构对裂纹的起始有着非常重要的影响.实验表明:某些具有微孔洞结构的陶瓷材料比相应的密实材料的抗热冲击性能有所提高,但相关的机制目前还没有得到定量的解释.本文作者利用商业有限元软件ABAQUS,分析了受热冲击表面上的开口微孔洞、处于表面附近的闭口微孔洞周围的热应力场,以及微孔洞的大小、微孔洞与表面的距离对热应力场的影响,其目的是为进一步分析裂纹的起始和扩展做准备.数值结果表明:一般情况下,闭口微孔洞引起的应力集中比开口微孔洞引起的应力集中更为严重,特别当闭口微孔洞与表面之间的距离很小时,和没有微孔洞情况相比,闭口微孔洞引起的最大的应力集中系数超过6.

关键词: 陶瓷 , 微孔洞 , 热应力 , 数值分析

从微孔洞起始的热冲击裂纹的数值研究--Ⅱ:能量释放率分析

贺鹏飞 , 李京剑 , Yuan C , Stern R , Clegg W J

复合材料学报 doi:10.3321/j.issn:1000-3851.2002.05.016

利用商业的有限元软件ABAQUS,分析了具有微孔洞结构氧化铝陶瓷材料在受到热冲击作用下,从处于材料表面上的开口微孔洞以及临近材料表面的闭口微孔洞的底部起始的裂纹扩展.结果表明:对于从开口微孔洞和闭口微孔洞底部起始的裂纹,其能量释放率随冷却时间的变化规律类似,即随冷却时间t由零开始增加,能量释放率也由零开始快速增大,在冷却时间大约为t=0.1 s时,达到其最大值,随后开始降低.另外对于从开口微孔洞底部起始的裂纹,结果发现裂纹的能量释放率随裂纹长度的增加、微孔洞半径的增加而增加,而对于从闭口微孔洞底部起始的裂纹,其能量释放率随裂纹长度的增加、微孔洞半径的增加、以及微孔洞与材料受热冲击面距离的增加而增加.以开口微孔洞底部起始的裂纹为例,研究了裂纹与临近微孔洞之间的作用,发现临近微孔洞的存在可以明显减小裂纹的能量释放率.这些结果对于从材料的微结构角度设计材料的抗热冲击性能有参考价值.

关键词: 裂纹 , 热冲击 , 能量释放率 , 微孔洞

TENSILE TESTING OF C/C COMPOSITES ATHIGH TEMPERATURES

Author S.R. Zhou , S.R. Qiao , S.H. Bai and C.S. Tian Faculty 401 , Northwestern Polytechnical University , Xian 710072 , ChinaManuscript received 18 October 1998

金属学报(英文版)

The tensile properties of three different carbonfiberreinforced carbon composites (C/C), mat C/C, 2D laminate and 4D C/C, were investigated under the combined influence of temperature and loading rate. From the experiments the following could be concluded: loading rate between 10-1-10 mm/min was valid; the fracture stress of the three kinds of C/C composites increased with increasing temperature in the range from room temperature to 1900, and the initial modulus of 2D laminate C/C composites increased with the increase of temperature up to 2000.

关键词: tensile testing , null , null , null

C/C-PAA与C/C-FA弯曲性能对比

张万强 , 赵英民 , 王涛 , 詹万初

宇航材料工艺 doi:10.3969/j.issn.1007-2330.2014.05.012

通过PIP工艺制备了C/C-PAA、C/C-FA复合材料,对PAA、FA裂解碳的XRD、浸渍效果以及C/C-PAA和C/C-FA的弯曲强度进行了分析.结果表明:PAA裂解碳的炭质量、浸渍效果较好,C/C-PAA弯曲强度比C/C-FA弯曲强度高34.9％,弯曲模量对比不明显.

关键词: 聚芳基乙炔 , 糠酮树脂 , X射线衍射 , C/C复合材料

偏光观察C/C复合材料

张保法 , 阮宏武 , 李东生

材料工程 doi:10.3969/j.issn.1001-4381.2006.01.008

利用正交偏光可分辨C/C复合材料中不同类型的沉积炭,通过旋转检偏器可测量C/C复合材料中沉积炭的消光角度.列举了偏光观察C/C复合材料实验过程中经常遇到的问题,介绍了测定消光角度的方法,简要概述了近年来研究热解炭各向异性的成果.

关键词: C/C复合材料 , 化学气相沉积 , 消光角度 , 偏光显微镜

C/C及C/C-Cu复合材料的摩擦磨损性能

孙乐 , 方向青 , 孟广慧

材料科学与工程学报 doi:10.14136/j.cnki.issn 1673-2812.2016.05.027

通过化学气相渗透(CVI)、树脂浸渍/碳化(I/C)的工艺制成多孔的C/C预制件,采用气体压力浸渗方法向预制体中渗入铜,制备出C/C-Cu复合材料.以高密度C/C复合材料(1.9g/cm3)作为对比样,在MM-200型磨损试验机上对其摩擦磨损性能进行测试,并对其微观结构和摩擦磨损机理进行分析.研究结果表明:C/C-Cu的摩擦系数比C/C复合材料的低,这主要与摩擦表面的摩擦膜有关,铜在摩擦力带动下填充摩擦表面的凹坑,并与碳材料共同形成摩擦膜,摩擦膜的碳含量越高,润滑效果越好.当C/C预制件密度为1.59 g/cm3时,C/C-Cu的摩擦系数和磨损量均小于C/C复合材料,摩擦磨损性能良好.

关键词: C/C-Cu , 摩擦磨损 , 摩擦膜

Electronic transport properties of NbC(C)-C nanocomposites

Physical Review B

We report the electronic transport properties of a composite system comprising zero dimensional superconducting NbC(C) nanocapsules and carbon nanofiber matrix. DC susceptibility measurements of the nanocomposite indicate that the critical temperature (T-C) of NbC nanocrystals is 10.7 K. The temperature dependence of electrical resistivity of the specimen pellet follows the Mott's T-1/4 law in a temperature range between T-C of NbC and 300 K, owing to a strong degree of structural disorder in the carbon matrix. Below the T-C of NbC, when the change of its electrostatic energy Delta E is far greater than the thermal energy, an electron will be localized on an isolated NbC nanocrystal at very low temperatures, leading to "Coulomb Blockade." As a result, a collective behavior of the single-electron tunneling effect takes place in a three-dimensional granular superconductors' network composed of the NbC/carbon/NbC tunneling junctions. The superconducting gap of NbC crystals is not found in the current-voltage curves, due to the suppression of surface superconductivity through the contact between NbC and carbon shells.

关键词: zero-dimensional superconductor;granular metal-films;particles;conduction;nanocapsules;percolation;samples

Oxidation behavior of C/C-SiC gradient matrix composites

材料科学技术（英文）

Oxidation behavior of C/C-SiC gradient matrix composites and C/C composites were compared in stationary air. The results show that oxidation threshold of C-SiC materials increases with the amount of SiC particles in the codeposition matrix. Oxidation rate of C/C-SiC gradient matrix composites is significantly lower than that of C/C material. The micro-oxidation process was observed by SEM.

关键词: carbon carbon composites

Oxidation behavior of C/C-SiC gradient matrix composites

Jingyi DENG , Wenchuan LIU , Haifeng DU , Huiming CHEN , Yiyi LI

材料科学技术（英文）

Oxidation behavior of C/C-SiC gradient matrix composites and C/C composites were compared in stationary air. The results show that oxidation threshold of C-SiC materials increases with the amount of SiC particles in the codeposition matrix. Oxidation rate of C/C-SiC gradient matrix composites is significantly lower than that of C/C material. The micro-oxidation process was observed by SEM.

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