pH值对Q235钢在模拟酸性土壤中腐蚀行为的影响

Effect of pH values on the corrosion behavior of Q235 steel in simulated acidic soils

通过腐蚀失重计算、扫描电镜、X射线衍射方法、极化曲线分析等手段,研究了p H值对Q235钢在模拟酸性土壤中腐蚀行为的影响.在模拟酸性土壤环境中,Q235钢的腐蚀速率随土壤p H值升高而降低,经360 h腐蚀后,在p H值为4.0、4.5和5.1的土壤中试样的腐蚀速率分别为0.68、0.48和0.42 mm·a-1.随土壤p H值升高,Q235钢锈层更为致密,其表面蚀坑由窄深型发展变为宽浅型发展.腐蚀产物均为Si O2、α-Fe OOH、γ-Fe OOH、Fe2O3及Fe3O4,随土壤p H值升高,腐蚀产物中α-Fe OOH/γ-Fe OOH质量比升高.极化曲线分析表明,随土壤p H值升高,Q235钢腐蚀电位升高,自腐蚀电流密度降低,试样腐蚀速率减小.

The effect of pH values on the corrosion behavior of Q235 steel in simulated acidic soils was investigated by weight-loss measurement, scanning electron microscopy （SEM）, X-ray diffraction （XRD） analysis and polarization curve analysis. When the pH values are 4. 0, 4. 5 and 5. 1, the corrosion rate of Q235 steel are 0. 68, 0. 48 and 0.42 mm-a-1, respectively. With the increase of soil pH values, the rust becomes more compact and the etch pits change from narrow and deep to wide and shallow. All the corrosion products are mainly composed of SiO2 , a-FeOOH, ＂y-FeOOH, Fe203 and Fe304, and the mass ratio of a-FeOOH/Y-FeOOH in the corrosion products is higher with increasing pH values. Additionally, polarization curve analysis shows that when the soil pH value ri- ses, the corrosion potential of Q235 steel increases, the corrosion current density decreases, and the corrosion rate becomes lower.