镍磷化学镀层在北方重工业城市雪水中的耐蚀性

为了改善Q235钢在空气污染较为严重的环境中的耐蚀性,以北方重工业城市之一的抚顺望花区的雪水为腐蚀溶液,考察了化学镀镍层在该介质中的耐蚀行为。采用金相显微镜观察了镍磷镀层的表面形貌,通过冷冻-加热循环试验考察了镀层的结合力,借助动电位极化、电化学阻抗谱等方法评价了镀层在雪水中的耐蚀性,测试和观察了浸泡实验的腐蚀速率和表面形貌。结果表明,Ni-P镀层可在Q235钢表面均匀沉积且较为致密,与基体之间有良好的结合力。镀层的自腐蚀电流密度较Q235钢低,电荷转移电阻更大,腐蚀速率是Q235钢的1/3～1/2。Ni-P镀层明显改善了Q235钢在污染较为严重的雪水中的耐蚀性,可作为Q235钢腐蚀防护的一种措施。

Corrosion resistance of electroless nickel-phosphorus deposit in snow water of north heavy industry city

To improve the corrosion resistance of Q235 steel in heavy air pollution environment,the corrosion behavior of electroless Ni-P coating in the snow water of Wanghua district in Fushun,a north heavy industry city in China,was studied.The surface morphology of the coating was observed by optical microscopy,and the adhesion strength was tested via freezing-heating circle test.The corrosion resistance of the deposit in snow water was evaluated using polarization curves and electrochemical impedance spectroscopy.The corrosion rate was calculated and the surface morphology observed after immersing the deposit in snow water.The results showed that the deposit is uniform and compact on the surface of Q235 steel and has good adhesion to substrate.The Ni-P deposit has lower corrosion current density and larger charge transfer resistance than Q235 steel.The corrosion rate of the Ni-P deposit is 1/3-1/2 of that of Q235 steel.Ni-P deposit remarkably improves the corrosion resistance of Q235 steel in snow water with heavy air pollution,which can be used as a measure for corrosion protection of Q235 steel.