表面渗层和CrNiMo涂层材料的露点腐蚀*

基于我国电站锅炉排烟温度普遍偏高、烟气深度冷却利用过程中存在露点腐蚀的现状,文中以耐露点腐蚀材料316L钢作为对比材料,选取普通碳钢进行表面热喷涂和表面渗镍处理后在1000MW机组的锅炉上进行实炉露点腐蚀试验。结果表明:材料的腐蚀层厚度随壁面温度升高而减小;在40～60℃的金属壁面温度范围内,碳钢表面CrNiMo涂层和渗镍层因表面缺陷导致涂层严重腐蚀;在70～90℃的金属壁面温度范围内,腐蚀层厚度随温度变化趋于平稳,表面渗层材料具有和316L钢相当的耐露点腐蚀能力,碳钢表面喷涂CrNiMo耐腐蚀性能更为优越,3种材料均能满足火电厂烟气深度冷却利用的露点腐蚀性环境。

Dew Point Corrosion of Nickelizing Layers and CrNiMo Coatings

To solve the problem of high exhaust temperature of power boiler and the existed dew point corrosion in the process of deep flue gas cooling,the CrNiMo coating and nickelizing coating were prepared on carbon steel to carried out the dew point corrosion experiment on a boiler with 1000 MW power plant,in contrast with 316L steel.The results show that the thickness of corrosion layer is reduced with increasing of the wall temperature.CrNiMo coatings and nickelizing layers show serious corrosion due to the defects on their surface under the wall temperature from 40 to 60 ℃.Meanwhile,the thickness of corrosion layer is stable in the wall temperature from 70 to 90 ℃.The dew point corrosion resistance of nickelizing layers is equivalent to that of 316L steel.The CrNiMo coatings show superior dew point corrosion resistance to 316L steel.Moreover,the three materials meet all the needs of the environment which exist dew point corrosion in the process of deep flue gas cooling in thermal power plant.