pH值对X70管线钢在北部湾钦州砖红壤模拟溶液中腐蚀行为的影响

Effect of pH Value on Corrosion Behavior of X70 Pipeline Steel in Simulated Solution of Latosol in Beibu Gulf Qinzhou

为探究X70管线钢在不同pH值下的腐蚀规律及机理,采用动电位极化曲线和电化学交流阻抗谱测试技术、质量法、X射线衍射技术研究了在恒温条件下不同pH值X70管线钢在北部湾钦州砖红壤模拟溶液中的电化学腐蚀行为。结果表明:随着pH值的降低,X70管线钢的容抗弧阻值不断减小,随之极化电阻减小,且自腐蚀电位负移,自腐蚀电流密度增加,X70管线钢溶解速率变大,腐蚀性增强。极化过程中,阳极X70管线钢活化溶解,阴极反应存在吸氧腐蚀和析氢腐蚀。溶液酸性越强,H^(+)会促进腐蚀产物FeO(OH)和Fe_(2)O_(3)向FeO(OH)的转变,并且H^(+)在反应过程中会生成氢气,造成腐蚀产物的疏松,对管线钢基体保护性变弱,腐蚀加剧。

To explore the corrosion law and mechanism of X70 pipeline steel at different pH values,using a potentiodynamic polarization curve and electrochemical impedance spectroscopy,gravimetric method,and X-ray diffraction technology under constant temperature conditions,the electrochemical corrosion behavior of X70 pipeline steel with various pH values in a simulated solution of Qinzhou brick-red soil in Beibu Gulf was investigated.The results show that as the pH value decreases,the capacitive arc resistance value of X70 pipeline steel decreases continuously,the polarization resistance decreases,the self-corrosion potential moves negatively,the self-corrosion current density increases,and the dissolution rate of X70 pipeline steel becomes larger and the corrosion is enhanced.The anode X70 pipeline steel is activated and dissolved during the polarization process,and the cathode reaction includes oxygen absorption corrosion and hydrogen evolution corrosion.More H^(+)facilitates the transition of the corrosion products FeO(OH)and Fe_(2)O_(3) to FeO(OH)as the acidity of the solution increases.Furthermore,H^(+)will create hydrogen throughout the reaction phase,resulting in loose corrosion products,weakened pipeline steel matrix protection,and worsening corrosion.