h-BN基复合陶瓷涂层防锅炉受热面的硫酸盐腐蚀性能

Sulfate Corrosion Resistance of h-BN Based Composite Ceramic Coatings for Boiler Heating Surface

针对燃煤锅炉受热面存在的硫酸盐腐蚀问题,采用料浆法在20CrMn表面制备h-BN基复合陶瓷涂层,分析了涂层的抗热震性能、孔隙率和耐磨性能,并研究了350～450℃范围内未喷涂和喷涂涂层试样的防硫酸盐腐蚀性能。结果表明,涂层的抗热震性能良好,孔隙率低,耐磨性能与基材相近。结合热分析动力学对腐蚀试验数据进行处理,得出两种试样腐蚀的反应机理均符合二级相界面反应类型。计算得到未喷涂涂层和喷涂涂层试样的反应活化能分别为1 431.172 J·mol^(-1)和2 200.217 J·mol^(-1),可见喷涂涂层试样的腐蚀反应活化能高于未喷涂涂层试样,表明喷涂涂层试样的防腐蚀性能优于未喷涂涂层试样。分析试验后喷涂涂层试样的形貌、成分和物相,发现该试样仅表面出现少量Na_2SO_4晶粒,而内部基本未检测到Na_2SO_4,表明喷涂涂层提升了基材的防腐蚀性能。

Sulphate corrosion is commonly occurred on the heating surface of coal-fired boiler.To address this problem,h-BN based composite ceramic coating was prepared on the surface of 20CrMn steel sheet by slurry method.Then,the thermal shock resistance,porosity and abrasive resistance of the coating were analyzed,and the sulfate corrosion resistance of the uncoated and ceramic-coated steel sheets at 350-450℃was investigated.The experimental results showed that the coated samples exhibit favorable thermal shock resistance,low porosity and similar wear resistance to the substrate.The corrosion test data were processed by employing thermal analysis kinetics,and the corrosion mechanism of both uncoated and coated samples was found to be in accordance with the second order phase interface reaction.It could be seen from the calculation results that the activation energy of coated sample(2 200.217J·mol^-1)was higher than that of uncoated one(1 431.172J·mol^-1),indicating that the sulfate corrosion resistance of coated sample was superior to the uncoated one.After corrosion test,the appearance,composition and phase of the samples were analyzed.The results showed that there was only a small amount of sodium sulfate(Na2SO4)crystal grains forming on the surface of the coating,while Na2SO4 was not detected in the interior of the sample.It turns out that the spraying coatings contributed to preventing the substrate material from the sulphate corrosion.