铝管蒸发器泄漏原因分析及质量改进

Leakage Failure Analysis of Al Tube in Evaporator and its Quality Improvement

铝管蒸发器是冰箱制冷系统的重要部件,铝管腐蚀泄漏导致制冷系统不起作用。本文利用扫描电子显微镜、金相显微镜、化学成分分析和微区分析、溶出实验和应力腐蚀实验等方法研究了铝管腐蚀失效的原因和特征。铝管腐蚀方向主要是由外向内侧进行的,具有晶间腐蚀特征。微区能谱分析表明铝管腐蚀微区中铁杂质分布不均匀,且明显超标,这是铝管腐蚀的内因。防腐涂层涂刷不均匀和发泡材料的腐蚀性介质是引起腐蚀的外部条件。蒸发器生产现场的某些工装可引起铝管破损,加速腐蚀。在上述研究基础上,本文提出了质量改进措施,并取得了良好效果。

Aluminium tube evaporator is an important component in the cold-producing system of refrigerator, and the Aluminium tube corrosion leakage will cause the system failure. The corrosion feature and causes are investigated in the paper by a scanning electronic microscopy, metallographic microscopy, elemental analysis, dissolving test of related polyurethane foam and stress corrosion test. The corrosion develops in the tube wall from external to internal side, in the feature of grain boundary corrosion. Elemental analysis by energy dispersion spectrum indicates that the content of impurities Fe is much higher in corrosive region than in standard sample and its distribution is not uniform, which shall be a internal cause for the corrosion. External cause for corrosion shall be due to the incomplete coats on the tube and small amount of corrosive medium from the polyurethane foam. In addition, some workshop scratches may accelerate the corrosion. Based on the failure analysis, some quality improvement measures are presented and a satisfactory result is received with the practice of the measures.