磷酸铵溶液介质中不锈钢球阀的失效分析

采用金相显微镜和扫描电镜,对在磷酸铵溶液中失效的不锈钢球阀进行了宏微观形貌观察和金相组织分析;并采用光电直读光谱仪、能谱仪、红外碳硫分析仪和NHO分析仪对球阀材质和密封部位表面沉积物进行了表征分析。结果表明,球阀的失效是由于材质不合格和环境介质的共同作用所产生的电化学腐蚀和结垢引起的。此外,分析了不锈钢材料在磷酸铵溶液中的腐蚀机理,并提出防止球阀失效的相应对策。

Failure Analysis of Ball Valve Made of Stainless Steel in Ammonium Phosphate Solution

The macro appearance,morphology and metallographic structure of ball valve which was made of stainless steel and failed in ammonium phosphate solution,were observed by metallographic microscopy and scanning electron microscopy(SEM).Also,photoelectronic direct reading spectrometer,energy dispersive spectrometer(EDS),carbon and sulfur analyzer and NHO-analyzer were also used to analyze the chemical composition of the substance and particles deposited on sealing area.The failure of ball valve was caused by electrochemical corrosion and scaling resulted from interaction of inferior materials and environmental medium.The corrosion mechanisms of stainless steel in ammonium phosphate solution were addressed and countermeasures for solving the problem were proposed as well.