Q235钢-紫铜在不同温度酸性红壤中的电偶腐蚀行为

Galvanic Corrosion Behavior of Q235 Steel-Red Copper in Acid Red Soil of Different Temperatures

目的研究Q235钢-紫铜电偶对在不同温度红壤中,电偶腐蚀的加速效应和腐蚀机理。方法通过恒温恒湿箱模拟不同温度的酸性红壤环境。采用失重法测定Q235钢-紫铜电偶对的电偶腐蚀动力学曲线,采用ZRA零电阻电流计研究电偶电流和电偶电位随腐蚀时间的变化曲线。通过XRD、SEM/EDS检测腐蚀产物的成分和微观形貌。结果电偶腐蚀20 d后,土壤温度为20、40、60℃Q235钢的腐蚀质量损失分别为0.4276、0.9432、1.4622 g/dm^2,电偶腐蚀效应分别为4.51、2.90、2.56。Q235钢在酸性红壤中呈局部腐蚀形态,当土壤温度为20℃和40℃时,腐蚀产物主要由FeO、Fe_3O_4与土壤颗粒胶结形成,结构较疏松;当温度为60℃时,腐蚀产物主要由Fe_3O_4组成,结构较致密。随着腐蚀时间的增加,电偶电位呈现起伏波动,电偶电流减小。腐蚀20 d后,Q235-紫铜电偶对在60℃下的电偶电流(71.1μA)小于20℃下的电偶电流(336μA),电偶腐蚀作用较弱。结论土壤温度越高,Q235钢腐蚀越严重。腐蚀进行的后期,温度较高的红壤中,Q235钢形成的腐蚀产物结构致密,且土壤氧含量低,对电偶腐蚀产生抑制作用。

The work aims to study the acceleration effect and galvanic corrosion mechanism of Q235 steel-red copper in red soil with different temperatures.The environment of acid red soil with different temperatures was simulated by constant temperature and constant humidity box.The galvanic corrosion kinetics curves of the Q235 steel-copper were measured by weight-loss method.The zero resistance galvanometer(ZRA)was used to study the variation curves of the galvanic potential and galvanic current with the corrosion time.Microstructure,composition and phase of the corrosion products were analyzed with XRD,SEM/EDS,respectively.After 20 d of galvanic corrosion,the galvanic corrosion weight loss of Q235 steel at soil temperature of 20,40 and 60°C was 0.4276,0.9432 and 1.4622 g/dm2 respectively,and the galvanic corrosion effect was 4.51,2.90 and 2.56,respectively.Q235 steel exhibited local corrosion in the acid red soil.The corrosion products were mainly composed of FeO and Fe3〇4,cemented with soil particles and the structure of the corrosion products was loose when the temperature was 20°C and 40°C.The corrosion products were mainly composed of Fe30 4 when the temperature was 60°C and the structure of the corrosion product was dense.As the corrosion time increased,the galvanic potential fluctuated and the galvanic current decreased.The galvanic current of Q235 steel-red copper at 60°C(71.1(iA)was lower than that at 20°C(336(iA)for 20 days.The corrosion became worse as the temperatures of soil increased.In conclusion,the corrosion of Q235 steel is worse as the soil temperature is higher.In the later period of corrosion,the oxygen content in the soil with higher temperature is lower and the structure of the corrosion product is more compact,so the galvanic corrosion process is inhibited.