天然海水中钼酸盐复合缓蚀剂对A3钢的缓蚀效果

Corrosion Inhibition of Molybdate Composite Inhibitor for A3 Steel in Natural Seawater

已有的海水缓蚀剂多局限于模拟环境,在天然海水中的适应性较差。将A3钢浸于添加了钼酸盐复合缓蚀剂的海水中,研究了浸泡时间、缓蚀剂组分投加顺序、海水温度、氯离子浓度、pH值、杀菌剂类型对缓蚀剂缓蚀效果的影响。结果表明:试片在含有钼酸盐复合缓蚀剂的海水中浸泡40min的阻抗谱直径比浸泡24h的稍大,在空白海水中浸泡40min和24h的阻抗谱直径相差较大,即复合缓蚀剂对浸泡时间有一定的适应性;缓蚀剂组分投加时先加入钼酸盐,试片自腐蚀电位最大,阳极极化曲线斜率变化较明显,该缓蚀剂是以钼酸盐为主剂的复合型缓蚀剂;复合钼酸盐缓蚀剂在海水温度为30～60℃、pH值为6～10内使用,缓蚀率变化较小,对冷却水系统常用的杀菌剂也有良好的适应性,并适用于NaCl质量分数小于8%的海水循环冷却系统。

A3 steel was immersed in seawater containing molybdate composite inhibitor,and the effects of immersion time,introducing order of inhibitor ingredients,seawater temperature,Cl-concentration,pH value and type of germicides on inhibition efficiency were investigated.It was found that the capacitance arc diameter of the flake specimen immersed in the seawater containing molybdate inhibitor for 40 min was slightly larger than that of the flake specimen immersed in the same medium for 24 h,which indicated that the molybdate composite inhibitor had some adaptability to immersion time.When molybdate was introduced into seawater at the beginning,the tested flake specimen had the highest self-corrosion potential,and the slope of anodic polarization curve changed obviously,which indicated that the inhibitor was a kind of composite inhibitor with molybdate as the major agent.Besides,at a seawater temperature of 30～60 ℃ and pH value of 6～10,the inhibition efficiency changed slightly.The inhibitor showed good adaptability to germicides commonly used in the cooling systems,and was applicable to the cyclic cooling systems of seawater containing less than 8%NaCl (mass fraction).