摘要
油田地下水中HCO3-含量较高,对油田套管钢J55的电化学行为有较大影响。为此,利用动电位极化曲线和扫描电镜(SEM)研究了J55钢在不同浓度NaHCO3溶液中的腐蚀行为。结果表明,在试验条件下,HCO3-的浓度低于5g/L(即0.06mol/L)对J55钢的腐蚀起促进作用,高于5g/L起抑制作用;随着HCO3-浓度的增加,J55钢的二次钝化速度增大,钝化区间范围增大,维钝电流密度减小;J55钢的击穿电位降低,基本维持在1.00～1.15V之间;随着HCO3-浓度的增大,阴极反应速率增大,O2+4HCO3-+4e→4CO32-+2H2O是主要的阴极反应,而O2+2H2O+4e→4OH-反应是在-0.9V以后才开始发生的。
The effect of the concentration of HCO-3 on corrosion behavior ofJ55 steel was studied by using a potentiodynamic polarizationcurve measurement system and a scanning electron microscope,where J55 steel was tested in aqueous solution of NaHCO3 withvaried concentrations.Results show that under the present experi-mental conditions,HCO-3 accelerates corrosion of the steel at aconcentration below 0.06 mol/L,and it inhibits corrosion of thesteel at a concentration above 0.06 mol/L.With the increase ofconcentration of HCO-3,both the secondary passivation rate andrange were increased,the passivation current was reduced,andthe rupture potential was reduced in a range of 1.00～1.15V.At the same time,the cathodic reaction rate increased with in-creasing concentration of HCO-3,and an abrupt change of polari-zation current occurred when polarization potential was about-0.9 V.The main cathodic reaction for J55 steel in aqueous so-lution of NaHGO3 could be expressed as:O2+4HCO-3+4e→4CO2-3+ 2H2O.The cathodic reaction O2+2H2O+4e→40H onlv might appear at a polarization potential above-0.9V.
出处
《材料保护》
CAS
CSCD
北大核心
2010年第2期26-28,共3页
Materials Protection
