材料期刊网

借助于光学显微镜和扫描电镜、电子能谱仪对高压汽包锅炉 水冷壁管爆破口形貌、组织以及附着的腐蚀产物成分和化学状态进行研究.结果表明，炉 水中存在过量游离NaOH和水冷壁管存在局部过热是造成炉管凿槽腐蚀的两个基本原因. 提出了炉水中游离碱含量的精确算法并定量分析了一级除盐水电导率与其中游离NaOH含 量之间的关系及其对炉水游离碱的影响.补给水品质不良是造成炉水中游离NaOH过高的 主要原因.要防止炉管碱腐蚀就必须保持锅炉受热面清洁，控制炉水游离碱含量，避免炉膛 偏燃及火焰冲蚀，消除焊瘤及其它干扰炉水流动的因素.努力提高锅炉补给水品质，将其电 导率控制在适当的标准以下尤为重要.

The microstructure,crack shape,appearance of the fr acture and the composition of the corrosion product were studied with the help o f optical microscope,scanning electron microscope (SEM)and electron spectromete r.Investigations confirmed that the boiler tube failed from both the superfluous free hydroxyl in boiler water to determine which a new method has been devised and the local overheat caused by deposition in boiler tubes.The relationship bet ween conductivity and free sodium hydroxide at simple makeup demineralizer efflu ent was proposed.It was found that the poor quality of makeup water was the root cause of superfluous free hydroxyl in boiler water.The long-term prevention of crater corrosion will include:keeping a clean boiler,controlling boiler free hyd roxyl levels,avoid flame impingement or burner misalignment,and eliminating weld protrusions and other features that can disrupt the local boiler water flow.It is also extremely important that the makeup water treatment is optimized,and con ductivity controlled to a specified limit.