Ni-P化学镀层对工业锅炉腐蚀防护的可行性研究

Feasibility Study of Ni-P Electroless Coating on Corrosion Protection of Industrial Boiler

在炉管表面化学沉积Ni-P合金镀层。通过扫描电镜观察了镀层的微观形貌,通过能谱仪测试了镀层中磷的质量分数,通过X射线衍射仪分析了镀层的结构。借助极化曲线和交流阻抗等电化学技术比较了碳钢和Ni-P化学镀层在锅炉水中的腐蚀性。结果表明:该镀层致密均匀,其中磷的质量分数可达12%以上。当碳钢表面沉积镀层以后,自腐蚀电流密度由原来的29.69μA/cm2下降到4.34μA/cm2,电荷转移电阻由301.6Ω·cm2增加到3 236Ω·cm2,镀层明显提高了碳钢材料的耐蚀性。这主要是因为镀层为非晶态结构,没有晶界、位错等缺陷,容易形成具有保护作用的钝化膜,降低了炉管的腐蚀速率。

The electroless Ni-P coating was deposited on the boiler tube surface.The micro-morphology of the coating was observed by scanning electron microscope （SEM）,the mass fraction of phosphorus in the coating was tested by energy dispersive spectroscopy （EDS）,and the structure of the coating was analyzed by X-ray diffraction（XRD）.The corrosion behaviors of carbon steel and the electroless Ni-P coating in boiler water were compared with the aid of polarization curves and electrochemical impedance and other electrochemical techniques.The results show that the coating is compact and uniform,in which the P mass fraction is above 12 %.When the carbon steel surface is deposited with the coating,the selfcorrosion current density decreases from 29.69 μA/cm^2 to 4.34 μA/cm^2,the charge transfer resistance increases from 301.6 Ω · cm^2 to 3 236 Ω · cm^2,hence the coating can significantly improve the corrosion resistance of carbon steel.This is mainly because the coating is amorphous structure,with no grain boundaries,dislocations,etc.,easy to form a protective passivation film,so the corrosion rate of boiler tube is reduced.