刘持栋
,
成来飞
,
梅辉
,
栾新刚
,
周俊
无机材料学报
doi:10.3724/SP.J.1077.2008.00729
采用应力比为0.1, 频率为3Hz的正弦波分别在室温和1300℃水氧环境对2D C/SiC复合材料进行了拉-拉疲劳试验．结果表明, 若取循环基数为105, 室温和高温水氧环境下的疲劳极限分别为244.8MPa和93.3MPa, 高温下的水氧腐蚀是材料失效的主要原因．根据疲劳断口特征分析得出以下结论: 在高温水氧环境下, 足够大的外载荷将会显著削弱SiO2层的封填裂纹效果, 导致氧化性气氛通过外力拉开的微裂纹扩散进入材料内部．外载荷越大, 气体在材料内部的扩散越快, 复合材料的疲劳寿命越短．
关键词:
2D C/SiC复合材料
,
fatigue
,
high temperature
,
oxidation
牛焱
腐蚀学报（英文）
研究了含15与30wt%Nb的两种Co-Nb合金在600-800℃低氧压F的氧化性能选择的氧压低于相应温度的氧化钴分解压,由H2-CO2混合气获得,在600℃为10-24atm,而700与800℃为10-20atm.两种合金在600与700℃氧化结果仅产生由α-CO与氧化铌(NbO2与Nb2O5)混合物组成的内氧化带在700℃尚可能生成双元氧化物CONb2O6在内氧化带界而无贫Nb层可见.两会金,尤其是Co-30Nb在800℃时发生了由内氧化向外氧化的转变,伴随有贫Nb的单相区出现于合金的表层.从Co中N
关键词:
Co-Nb合金
,
high temperature
,
oxidation
金云学
,
王小丫
,
童强强
,
Jung-Moo Lee
稀有金属材料与工程
采用T6态的SiCp/A356复合材料,以Al2O3陶瓷球作为对磨材料,借助UMT-2摩擦磨损实验机详细研究了复合材料的高温摩擦磨损性能,并采用SEM、OLS4000等手段分析材料的高温摩擦磨损特性.结果表明:T6态的SiCp/A356复合材料的磨损率随着温度的增加而增加.当温度低于150℃时,磨损率随温度缓慢增加;继续升高温度,磨损率进入稳定阶段,稳定磨损率为3.18×10-5 mg·cm1;当温度达到250℃时,磨损率呈线性上升.摩擦系数则随温度在0.40～0.45很小范围内波动,表现出优异的高温摩擦性能.同时,磨损机制由氧化磨损、磨粒磨损和疲劳磨损转变为严重的粘着磨损.
关键词:
SiCp/A356
,
T6热处理
,
高温
,
滑动摩擦磨损
,
磨损机制
季波
,
沈寅忠
,
黄希
机械工程材料
在应变速率为2×10-5～1×10-3s-1范围内以及不同温度(600～700℃)下,对11Cr铁素体/马氏体钢进行拉伸试验,研究其在变形过程中的锯齿流变现象.结果表明:试验钢在变形过程中出现了“反常”锯齿流变,且只出现一种E型锯齿波;锯齿开始出现在拉伸应力最大值附近,锯齿波主要处于拉伸曲线的下降段;锯齿形成的有效激活能约为43.44 kJ·mol-1;高温时,置换原子气团能量高,完全钉扎住位错,当一定数量的位错达到临界运动速度时,摆脱了置换原子气团的钉扎,从而导致产生锯齿流变现象.
关键词:
11Cr铁素体/马氏体钢
,
动态应变时效
,
锯齿流变
,
激活能
,
高温
陈辰
,
张海斌
,
彭述明
,
龙兴贵
,
朱建国
材料研究学报
研究了Ti3AlC2体材料在氢气氛中的高温(1100～1400C)热稳定性.采用XRD、SEM、SIMS和Raman分析等手段对Ti3A1C2临氢反应前后的物相组成、表面形貌进行了表征;使用热力学软件Factsage计算了反应过程中的气态产物.结果表明,在1100～1400℃氢气氛条件下有少量H溶解在Ti3AlC2材料中,Ti3AlC2发生了以A1元素缺失为特征的有限程度的分解反应.缺失的A1元素与气氛中极微量的氧反应形成了均匀但不致密的Al2O3膜;而当反应温度为1400℃时,Al2O3膜发生了明显的脱落.使用热力学软件的计算结果预测,部分缺失Al元素与H2反应生成气体产物AlH.初步的研究结果表明,在1300℃以下TiAlC2具有较好的耐氢性能.
关键词:
无机非金属材料
,
临氢
,
高温
,
Ti3AlC2
M. Sakane (Department of Mechanical Engineering
,
Faculty of Science and Engineering
,
Ritsumeikan University
,
1-1-1Nojihigashi Kusatsu-shi Shiga
,
525-8577
,
Japan)S. Mukai (Power Reactor and Nuclear Fuel Development Corporation
,
4002 Narita-cho Oarai-cho Ibaragibun Ibaragi
,
311-13
,
Japan)
金属学报(英文版)
This paper describes new methods for biaxial and triaxial creep testing. Biaxial tension and triaxial tension creep testers were developed. The performance of the machines was described and some test results were discussed. Stress biaxiality had almost no effect on the creep deformation and Mises potential was suitable for describing the creep deformation under biaxial and triaxial stress states. Stress biaxiality had a small influence on prolonging creep rupture time under the constant Mises stress condition.A new triaxial tension creep testing method was discussed together with the shape of the triaxial creep specimen.
关键词:
creep
,
null
,
null
,
null
,
null
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
Author S.H. Bai
,
S.R. Qiao
,
S.R. Zhou and M.K. Kang Faculty 401
,
Northwestern Polytechnical University
,
Xian 710072
,
China Manuscript received 18 October 1998
金属学报(英文版)
In this paper, the influence of loading rate and specimen height on flexural strength of Al2O3 at high temperatures has been studied by three-point bending method. The experimental results show that the flexural strength of Al2O3 decreases with increasing specimen height at room temperature, and it tends to stability when height increases to a certain degree (h=5mm in this paper), while the flexural strength of Al2O3 variates unapparently at high temperature with increasing height. There is a critical loading rate R . c. When loading rate R . is less than R . c, the flexural strength of Al2O3 increases with increasing loading rate and it drops sharply when loading rate is higher than R . c. The sensitivity of flexural strength to the loading rate decreases with elevating temperatures.
关键词:
loading rate
,
null
,
null
,
null
李明飞
,
迟重然
,
任静
,
蒋洪德
工程热物理学报
透平进口温度持续提高,使得实验测试条件难以实现全温全压的测量,往往采用降温降压工况.本文采用耦合数值方法,分别针对耦合气膜冷却平板及耦合叶栅模型,分析多场耦合下的高 低温传热特征,探索透平冷却温度水平影响特性及机理.研究表明,综合冷却效率分布受金属、流体物性及内外部冷却多方面综合影响;比较无量纲参数相同的高-低温工况,高温使得有TBC涂层时综合冷效偏高,无TBC涂层时综合冷效偏低;无量纲参数相同的高-低温工况,在平板上综合冷却效率分布规律基本一致,在叶栅表面压力面和前缘较为一致,其余部分相差较多;在一定的温度差距内,高-低温工况结果仍可保持一定的一致性.
关键词:
耦合传热
,
高温
,
透平冷却
