研究碳钢在NaHCO3溶液中的阳极极化行为. 极化曲线测试表明,在 (0. 05 ~1. 0mol/L)NaHCO3浓度范围内,碳钢的阳极极化曲线都显示 2个电流峰和 2个钝化区,当HCO3-浓度低于 0. 1mol/L时,两电流峰相距很近,致使第 1个钝化区不易观察到. 而当HCO3-浓度>0. 1mol/L后,其第 1电流峰峰电流愈加上扬,而第 2电流峰峰电流反而下降. XPS分析表明,在较高电位下碳钢形成的表面膜,其外层主要成分为Fe2O3,而内层组成主要含Fe(Ⅱ)和Fe(Ⅲ)氧化物.
The anodic polarization curves of mild steel were measured in sodium bicarbonate solution of various concentrations, and the surface products were analyzed by XPS. Two anodic current peaks and two passive zones are observed in all the curves. When HCO_3~- ions concentration is below 0.1mol/L, the two peaks are so close that the first passive zone is difficult to be observed. When HCO_3~- ions concentration is above 0.1 mol/L, the first peak appears clear, while the second becomes smaller. The XPS results indicate that the out layer of film formed at a higher potential is mainly composed of Fe_2O_(3,) and the inner film is a mixture of ferrous and ferric oxide.
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