食品级磷酸浓度对国产904L不锈钢耐蚀性的影响

Effect of Food Grade Phosphoric Acid Concentration on Corrosion Resistance of Domestic 904L Stainless Steel

采用动电位极化曲线和电化学阻抗谱(EIS)研究了常温下国产904L不锈钢在不同浓度食品级磷酸中的腐蚀行为,并观察电化学测试后的腐蚀形貌。结果表明,国产904L不锈钢在25%食品级磷酸中具有良好的耐腐蚀性能,随着磷酸浓度的增加,自腐蚀电流密度Jcorr先增加后降低,浓度在40%时Jcorr最大,抗腐蚀性能最差。EIS曲线由高频端容抗弧和低频端Warburg阻抗组成,表明904L的腐蚀由电化学反应控制转为主要由扩散控制。

Potentiodynamic polarization curves and electrochemical impedance spectroscopy （EIS） were used to study the corrosion behavior of a domestic 904L stainless steel at room temperature in food grade phosphoric acid of different concentrations. And the corrosion morphologies were observed. The results showed that the domestic 904L stainless steel in 25% food grade phosphoric acid had good corrosion resistance. With the increase of phosphoric acid concentration, the natural corrosion current density J increased first, and then decreased. At the 40% concentration, the natural corrosion current density Jcorr was the largest and the corrosion resistance was the worst. Impedance spectrum curve consisted of the capacitive reactance arc at high frequency and the Warburg impedance at low frequency, inclicating that the corrosion of 904L was controlled by electrochemical reaction, and then turned to be controlled by material diffusion mainly.