D.Han
,
S.R.Qiao
,
M.Li
,
J.T.Hou
,
X.J.Wu
金属学报(英文版)
The differences of tension-tension fatigue and tensile creep characters of 2D-C/SiC and 3D-C/SiC composites have been scrutinized to meet the engineering needs. Experiments of tension-tension fatigue and tensile creep are carried out under vacuum high temperature condition. All of the high temperature fatigue curves are flat; the fatigue curves of the 2D-C/SiC are flatter and even parallel to the horizontal axis. While the tension-tension fatigue limit of the 3D-C/SiC is higher than that of the 2D-C/SiC, the fiber pullout length of the fatigue fracture surface of the 3D-C/SiC is longer than that of the 2D-C/SiC, and fracture morphology of the 3D-C/SiC is rougher, and pullout length of the fiber tows is longer. At the same time the 3D-C/SiC has higher tensile creep resistance. The tensile curve and the tensile creep curve of both materials consist of a series of flat step. These phenomena can be explained by the non-continuity of the damage.
关键词:
2D-C/SiC
,
null
,
null
Hejun Li
材料科学技术（英文）
2D needle-punched fiber felt was infiltrated by a kind of rapid isothermal chemical vapor infiltration technique.
The infiltration process and texture transition of the infiltrated C/C composites were investigated. The porosity
and the variations of the cumulative pore volume were determined by mercury porosimetry. The texture of
matrix carbon was studied under a polarized light microscope. The results show that the relative mass gain
of the sample increases directly as the infiltration time at the initial stage until 20 h, and subsequently the
increasing rate of the relative mass gain decreases gradually with the prolonging of infiltration time. Three layers
of pyrocarbon were formed around fibers. Low-textured pyrocarbon was obtained at the initial stage. With the
densification going on, high-textured pyrocarbon was formed on the surface of low-textured pyrocarbon. Then,
low-textured pyrocarbon was produced again during the final stage of densification. The texture transition is
ascribed to the variation of the ratio of cumulative inner surface area to volume of pores and the gas partial
pressure in pores.
关键词:
C/C composites
,
Isothermal chemical vapor infiltration (ICVI)
,
Pyrocarbon
,
Mercury porosimetry
,
Polarized light microscope
周颖
,
黄志尧
,
王保良
,
冀海峰
,
李海青
工程热物理学报
本文探讨了将电容耦合式非接触电导测量(Capacitively Coupled Contactless Conductivity Detection,C4D)技术应用于毫米级管径气液两相流气泡速度测量的可行性,提出了一种结合C4D技术及互相关测速原理的气泡速度测量新方法.研究包括两个部分:首先,结合串联谐振原理,研制了一种适用于气泡速度测量的新型三电极C4D传感器;其次,利用所研制传感器获得的两组电导信号,根据互相关测速原理实现气泡的速度测量.作为初步研究,在内径6.0 mm的竖直管内进行了气泡速度测量实验.实验结果表明将C4D技术运用于毫米级管径气液两相流气泡速度测量是可行的,所提出的气泡速度测量方法是有效的.
关键词:
电容耦合式非接触电导测量
,
毫米级管道
,
气泡
,
速度测量
,
互相关测速
Physics Letters A
The magnetic properties of the mixed ferro-ferrimagnetic compounds with (A(a)B(b)C(c))(y)D, in which A, B, C and D are four different magnetic ions and form four different sublattices, are studied by using the Ising model. And the Ising model was dealt with standard mean-field approximation. The regions of concentration in which two compensation points or one compensation point exit are given in c-a, b-c and a-b planes. The phase diagrams of the transition temperature T-c and compensation temperature T-comp are obtained. The temperature dependences of the magnetization are also investigated. Some of the result can be used to explain the experimental work of the molecule-based ferro-ferrimagnet ((NiaMnbFecII)-Mn-II-Fe-II)(1.5) [Cr-III (CN)6] - zH(2)O. (C) 2003 Elsevier B.V. All rights reserved.
关键词:
mixed ferro-ferrimagnet;Ising model;four sublattices;phase diagram;transition temperature;compensation temperature;magnetic-properties;prussian blue;alloy
嵇阿琳
,
马伯信
,
霍肖旭
,
刘红林
,
曾晓梅
,
李义和
新型炭材料
doi:10.3969/j.issn.1007-8827.2000.01.007
化学液气相沉积法(CLVD)是快速低成本制备C/C复合材料的一种新型工艺.通过叙述该工艺快速制备C/C复合材料的根本原因,并以1.5 mm/h的速度制备了炭布层叠2D C/C复合材料,同时对该材料进行了力学性能测试和金相分析.实验结果表明材料性能优越,说明该工艺是制备C/C复合材料的理想工艺.采用GC/MS质谱对煤油沉积回收物进行了成份分析,并对用CLVD法制备C/C复合材料的设备提出了一些改进建议.
关键词:
C/C复合材料
,
CLVD
,
金相分析
,
GC/MS
莎日娜
,
刘秀军
,
冯志海
,
樊桢
,
李同起
材料导报
2D-C/C复合材料是以二维碳纤维为增强体,以化学气相渗透的热解碳或液相浸渍炭化的树脂碳、沥青碳为基体组成的一种纯碳多相二维结构材料,是一种新型高性能结构功能复合材料,大量运用在航空航天等高新技术领域.目前研究集中于其宏观性能方面,难点在于其组织结构和性能的可控性、可调性.主要介绍了二维碳纤维预制体和针刺碳纤维,基体碳的微观结构和添加剂,纤维/基体界面和界面修饰,以及制备工艺对2D-C/C复合材料性能的影响.结合2D-C/C复合材料的结构特点,概述了2D-C/C复合材料热物理性能、力学性能及氧化烧蚀等行为的各向异性.此外,还展望了其研究发展方向.
关键词:
2D-C/C复合材料
,
热物理性能
,
力学性能
,
氧化烧蚀行为
李瑞珍
,
是旻
,
崔红
,
李贺军
,
郝志彪
宇航材料工艺
doi:10.3969/j.issn.1007-2330.2004.02.013
研究了采用化学气相反应法制备的SiC抗氧化涂层对3D整体编织C/C复合材料的密度、力学性能以及微观结构的影响.结果表明,3D C/C复合材料经抗氧化处理后,其密度、开孔率以及力学性能均有不同程度的提高.由SEM微观结构可以看出,其力学性能提高是由于气态Si渗入到材料基体内部,并与内部的C反应生成SiC,在一定程度上弥合了材料中的缺陷所致.
关键词:
C/C复合材料
,
抗氧化涂层
,
力学性能
,
微观结构
G.C.Ji
金属学报(英文版)
Based on the energy conservation, the elastic energy linked to the compliance change, non-elastic energy dissipated by irreversible deformation and the resistance for crack propagation were quantitatively characterized by evaluation the load/qoad point displacement curves tested by three points bend experiment with single notch beam at 1300℃. The cracks length was determined by compliance calibration curves. It is shown by experimental results that the compliance of 3D-C/SiC composites changes with the cracks can be described by third order polynomial. The variation of crack advancing resistance with non-dimensional equivalent crack length presents a convex curve. The crack advancing resistance increases firstly and then decreases with the non-dimensional equivalent crack length, finally is in comparatively low level. The maximum values of crack advancing resistance are 269.73k J/m^2 for nondimensional equivalent crack length of 0.318 and original notch length of 0.35mm, and 138.65kJ/m^2 for non-dimensional equivalent crack length of 0.381 and original notch length of 2.06mm, respectively.
关键词:
fracture resistance
,
null
,
null
