利用水热法合成了钼酸盐插层锌铝铈水滑石(ZnAlCe-MoO_4 LDH),并通过单因素试验和正交试验对水热合成过程中的n(Al(3+))/n(Ce(3+))摩尔比、反应温度、陈化温度等工艺参数进行了优化。利用扫描电镜、X射线衍射仪、红外光谱等对ZnAlCe-MoO_4LDH的形貌和结构进行了表征,并通过电化学阻抗谱、X射线光电子能谱等技术研究了ZnAlCe-MoO_4LDH对Q235碳钢在3.5%(质量分数)NaCl溶液中的缓蚀性能和缓蚀机制。结果表明,合成的ZnAlCe-MoO_4LDH呈片层状,片层厚度约为30 nm;ZnAlCe-MoO_4LDH的最佳制备工艺条件为:n(Al(3+))/n(Ce(3+))摩尔比6∶1,反应温度60℃,陈化温度100℃。ZnAlCe-MoO_4LDH对碳钢在3.5%NaCl溶液中的缓蚀作用,一方面体现在ZnAlCe-MoO_4LDH层板间的MoO_4(2-)会与溶液中的Cl-发生离子交换,降低了溶液中的Cl-含量;另一方面释放到溶液中的MoO_4(2-)会与Fe(2+)和Fe(3+)形成钼酸盐钝化膜,且层板上释放出的Zn(2+)和Ce(3+)会与OH-形成氢氧化物沉积膜,从而减缓了Q235钢在3.5%NaCl溶液中的腐蚀速率。
Molybdate intercalated ZnAlCe-hydrotalcite (ZnAlCe-MoO4 LDH) was synthesized by using solvothermal method, and the preparation parameters such as n(Al^3+)/n(Ce^3+) ratio, reaction temperature and crystallization temperature were optimized by single factor and orthogonal experi- ments. The surface morphology and structure of the prepared ZnAICe-MoO4 LDH were character- ized by SEM, XRD and FT-IR methods. The inhibition behavior of ZnAlCe-MoO4 LDH for Q235 steel in 3.5% (mass fraction) NaC1 solution were investigated by EIS and XPS. Results show that the synthesized ZnAlCe-MoO4 LDH presents laminar microstructure with the thickness of 30 nm. The optimum preparation conditions are n(Al^++)/n(Ce^3+) ratio of 6: 1, reaction temperature of 60℃ and crystallization temperature of 100℃. The inhibition effect of ZnAlCe-MoO4 LDH on the corro- sion of Q235 steel in 3.5%NaCl solution may be ascribed to the reduction of chloride concentration in 3.5%NaC1 solution owing to the anion exchange with molybdate, the formation of passive film with the composition of ferrous or iron molybdate and the deposition of film consisted of zinc and cerium hydroxides.