Measurements of Localized Ion Distribution and Nanoscopic AFM Observation of Crack Initiation and Propagation of Stress Corrosion Cracking

应力腐蚀裂纹萌生和扩展的局域离子分布测量和纳米级 AFM 观察

基本信息

批准号：
10650086
负责人：
MINOSHIMA Kohji
金额：
$ 2.24万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

In order to perform in situ observation of an initiation stage of corrosion damage including pitting corrosion and stress corrosion cracking, a so called chronoamperometric method was applied to localized corrosion damage, where a micron size Pt microelectrode (Diameter : 20 μm) is cyclically polarized by using a square waveform : local concentration of chloride ion and hydrogen ion, or pH values, can be respectively measured by using a current by an anodically and a cathodically polarized condition. By using this chronoamperometric method, distributions of chloride and hydrogen ion near a pitting corrosion was measured, at the bottom of which a stress corrosion crack sometimes initiates : the distributions of ions in and out of a corrosion pit was successfully measured, and the localization of ions around a pitting corrosion could be clearly visualized. In situ nanoscopic atomic force microscope (AFM) observation was also conducted to closely examine the growing process of stress corrosion cracking of a high-strength steel under a sustained loading : nanoscopic mechanism of stress corrosion cracking was discussed. Crack initiation and growth behavior was also investigated in a high-strength P/M Al-Zn-Mg alloy and a Ti-6Al-4V alloy under dynamic loading in order to clarify the environmental degradation behavior. Special attention was paid to the influence of combined loading on crack initiation and fracture behavior in a SiC whisker reinforced Al alloy.

为了在原位观察腐蚀损伤的机会阶段，包括蚀腐蚀和应力腐蚀开裂，将所谓的时间表测量方法应用于局部腐蚀损伤，使用平方波的局部ph lyogen pH Byolenty ph，使用氯化物的浓度或氢化量，在其中微米尺寸PT PT微电极（直径：20μm）被循环地化，阳极和阴极极化状态。通过使用这种计时度测量方法，测量了氯化物和氢离子在点蚀腐蚀附近的分布，在底部有时会引发应力腐蚀裂纹：成功测量了进出腐蚀坑的离子的分布，并且可以清楚地显示蚀刻腐蚀围绕离子的定位。还进行了原位纳米镜原子力显微镜（AFM）观察，以密切检查在持续负荷下高强度钢的应力腐蚀破裂的增长过程：讨论了应力腐蚀破裂的纳米镜头机制。还研究了在动态载荷下的高强度P/M al-Zn-mg合金和TI-6AL-4V合金中的裂纹主动性和生长行为，以阐明环境降解行为。特别注意合并负荷对SIC晶须增强AL合金中裂纹启动和断裂行为的影响。