流体力学因素对电极反应作用的定量分析

定义了流体力学因素对电极反应的作用系数(Ψa和Ψc),并进行了计算与分析.结果表明:在35% NaCl流动溶液中,随着流速的增大，仅碳钢腐蚀的阴极反应作用系数(Ψc)急剧增大,其腐蚀率也随之增大,流体力学因素主要加速了碳钢腐蚀的阴极反应过程.对介质充氮除氧后,相同流速条件下,只阴极反应作用系数(Ψc)才显著降低; 加入缓蚀剂后,阴、阳极反应作用系数(Ψa,c)的变化都不大.此时,流体力学因素对阴、阳极反应均无显著影响,碳钢腐蚀率基本不随流速而变化.可见,应用流体力学因素对电极反应的作用系数(Ψa,c),可以定量判定流体力学因素对电极反应的作用大小.

QUANTITATIVE ANALYSIS OF EFFECT OF HYDRODYNAMIC FACTOR ON ELECTRODE REACTION

Effect coefficients(Ψa and Ψc) of hydrodynamic factor on electrode reaction were defined and then analyzed.It was found that the effect coefficient (Ψc) of hydrodynamic factor on cathodic reaction of corrosion reaction for carbon steel in flowing 3.5% NaCl solution increases with increase of flow velocity,and results in increasing flow-induced corrosion rate of carbon steel.Hydrodynamic factor mainly speeds up the cathodic reaction process of corrosion reaction on carbon steel.After deaeration of the 3.5% NaCl solution with nitrogen,only Ψc decreased markedly in comparison with that without deaeration at the same flow velocity.However after addition of inhibitor into 3.5% NaCl solution,the effect coefficients of hydrodynamic factor on cathodic reaction (Ψc) and anodic reaction (Ψa) were little changed.Under this condition,hydrodynamic factor has almost no effect on cathodic reaction and anodic reaction,and results in little changes of flow-induced corrosion rate of carbon steel with increasing flow velocity.Therefore,the effect of hydrodynamic factor on corrosion electrode reaction in flowing corrosive media could quantitatively be analyzed with effect coefficients(Ψc,Ψa).