论文部分内容阅读
L C4CS铝合金是极为重要的航空材料 ,为评定其使用年限 ,在测定铝合金腐蚀疲劳裂纹的扩展速率时 ,需要弄清裂纹尖端金属的腐蚀电化学行为。在腐蚀环境中裂纹尖端由于不断裸露新鲜金属 ,因而将具有类似于双金属腐蚀时的电偶效应。为此 ,文中设计了一种新颖的缺口试样 ,再现裂纹尖端的真实状态。并在 3.5 % N a Cl溶液中测定剪切口断裂后 ,裸露出的新鲜金属在耦合前后腐蚀电位的变化 ,以及裸露面积、Na Cl溶液的 p H值与电偶电流的关系。测定自腐蚀电流对电偶电流值的影响 ,获得在耦合状态下裸露面积不等时腐蚀速率随时间的变化规律
L C4CS aluminum alloy is an extremely important aviation material. In order to evaluate its service life, it is necessary to know the corrosion electrochemical behavior of the crack tip metal when determining the rate of fatigue crack growth. In corrosive environment, the crack tip will have the galvanic effect similar to the bimetallic corrosion due to the constant exposure of fresh metal. For this reason, a novel notched specimen was designed to reproduce the true state of the crack tip. The change of corrosion potential of uncovered fresh metal before and after uncoupling was measured in 3.5% NaCl solution, and the relationship between the exposed area and the p H value of Na Cl solution and galvanic current was also measured. The influence of self-corrosion current on the galvanic current was measured, and the variation of corrosion rate with time was obtained when the exposed area was different