Campbell Laird(Dept. of Materials Science & Engineering
,
University of Pennsylvania
,
Philadelphia
,
PA 19104-6272
,
USA)Pedro Peralta(Center for Materials Science
,
Los Alamos National Laboratory
,
MaU Stop K765
,
Los Alamos
,
NM 87545-0001
,
USA)
材料科学技术（英文）
The mechanisms of fatigue crack propagation are breifly reviewed in relation to Professor McClintock's contributions to the early development of the field. The most securely established understanding has been obtained for those mechanisms of propagation involving plasticity-inducedgeometrical changes to the crack tip during tensile and compressive straining (the plastic blunting process). The roles of more complex factors in controlling the kinetics of crack propagation,which cause the magnitude of the Paris exponent to exceed 2, remain to be elucidated. Recentlyobtained results revealing the interconnection between the slip behaviour at the crack tip, theplastic blunting process and the dislocation structures present in the material before the crackencounters them are reported.
关键词:
Jiangming LU
,
Bangna ZHOU
,
Zhongxing YU
,
Shiguan CHEN+
,
Shanghai University of Technology
,
Shanghai 200072
,
China
材料科学技术（英文）
In this paper, the sintered Ti anodes (STA) with Ti suboxide intermediate layers and β-MnO_2 active layers were investigated in detail. At usual industrial current densities, the oxygen evolution overpotential on STA is reduced by 350 mV compared with lead anodes. According to the equation obtained experimentally, the service life of STA may be expected to be more than 3 years. After los- ing activity, STA may be recoated with β-MnO_2 active layers and used again. The electrocatalytic activity and the service life of the reused anodes remained almost unchanged. The possible reasons for losing activity of STA during the anodic evolution of oxygen were investigated by means of elec- tron probe microanalysis, electron scanning microscope and X-ray diffraction.
关键词:
sintered titanium anode
,
null
,
null
穆磊
,
马宇
,
贺志宏
,
董士奎
工程热物理学报
本文首先采用CFD—FASTRAN软件对RAM—CII钝锥体试验飞行器热化学非平衡绕流场参数进行了模拟分析，其次采取多温度模型结合逐线法获得非平衡绕流场吸收、发射系数，最终采用视在光线法LOS对RAM—CII飞行器全流场光辐射特性进行了模拟，分析表明：头部激波层紫外（02—0．4Dm）辐射最强，要比尾迹流区高3个数量级以上，正侧向观测辐射强度比迎头观测时要大接近1个数量级；同一方向不同高度总的光谱辐射亮度差别不大，但正侧向观测的光谱辐射亮度比迎头方向观测略大；绕流场红外（2～5μm）辐射以C02分子2．7、4．3μm谱带发射为主，但总体上看红外光谱辐射亮度相较于紫外要小3个数量级。
关键词:
高超声速钝锥体
,
热化学非平衡绕流场
,
光辐射特性
,
紫外辐射
,
红外辐射
