材料期刊网

作者在下列腐蚀体系中:(1)000 Cr17Ti 不锈钢在 H_2SO_4溶液中,(2)碳钢在一乙醇胺溶液中和(3)TC4钛合金在 H_2SO_4溶液中,用旋转电极电位滴定法研究了钒酸盐缓蚀剂的有效氧化态。结果发现,钒酸盐缓蚀剂的有效氧化态是+5,且各种五价钒化合物之间是等效的。通过钒酸盐临界致钝浓度与旋转圆盘电极转速关系的研究,作者确定了:(1)钛合金的致钝过程是由钒酸盐向钛合金电极表面的扩散过程所控制;(2)钒酸盐在钛合金表面进行的阴极反应中获得的电子数为1。

The effective oxidation state of vanadate corrosion inhibitor is determined by rotating disk electrode(RDE)potentiometric titration using NaVO_3 and/or VOSO_4 respectively in the following deaerated aqueous solutions:(1)stainless steel in 0.5MH_2 SO_4,(2)mild steel in CO_2-saturated 20% monoethanolamine solution,and (3)titanium alloy in 3.0MH_2 SO_4.It is found that NaYO_3,as a compound of pentapositive vanadium,can passivate these active-passive metals,but VOSO_4,as a compound of quadripositive vanadium,can not,so the effective oxidation state of vanadate corrosion inhibitor in aqueous solutions is+5,not +4.It is also found that as an oxidizing inhibitor,various compounds of pentapositive vanadium are equivalent in passivation process of metals. The variation of critical passivation concentration of NaVO_3 to ω~(-1,2)(ω-angular velocity of RDE) indicates that the passivation process of titanium alloy is determined by the diffusion rate of NaVO_3 in H_2 SO_4 solutions and one electron reduction to quadripositive vanadium takes place at the surface of titanium alloy.