尿素对土壤中Q235钢腐蚀的影响

Effects of Urea on Corrosion Behavior of Q235 Steel in Soil

利用电化学阻抗(EIS)和极化曲线等测试技术在湿度为30%的土壤中,研究了浓度为0.1%(质量分数)的氮肥尿素对碳钢腐蚀行为的影响。结果表明,实验初期尿素吸附在试样表面,阻抗谱呈现一个时间常数,且出现感抗。随着埋放时间的延长,尿素分解产生NH3,土壤pH值减小。碳钢的自腐蚀电位随时间正移,腐蚀速率降低。后期阻抗谱上出现Warburg扩散,表明腐蚀过程受扩散控制。

The effect of urea （0.1%, mass fraction） on corrosion of Q235 steel in soil with humidity of 30% was investigated by electrochemical impendence spectroscopy （EIS） and polarization curve. At the initial experiment period, urea was adsorbed on the surface of carbon steel, and one time constant with an inductive reactance arc appeared in the EIS. Along with the time, urea was decomposed into ammonia, hence pH decreased. The potential of carbon steel increased and its corrosion rate decreased over experiment time. Warburg impedance was found at the later stage, which indicated that the process was controlled by concentration polarization.