采用模拟闭塞区溶液研究NO_3~-对氯化钠溶液中0Cr18Ni9Ti钢的缓蚀作用及机理。结果表明,随着(NO_3~-)_(bulk)(主体溶液中NO_3~-的浓度)增高,闭塞区内金属的腐蚀速率减小,腐蚀电位向正方向移动。50℃时,若[NO_3~-]_(bulk)≥0.025或90℃时[NO_3~-]_(bulk)≥0.2M,闭塞区内金属由活态转变为钝态。当50℃、[NO_3~-]_(bulk)≥0.3M或90℃、[NO_3~-]_(bulk)≥0.5M时,其动电位极化曲线上的钝化区增宽、致钝电流密度和维钝电流密度变小,缓蚀率高达90％以上。因此,在主体溶液中加入适量NO_3~-能导致闭塞区钝化,从而对孔蚀、缝隙腐蚀及应力腐蚀破裂起缓蚀作用。
Simulated occluded solutions were used to study inhibition effect and its mechanism of NO_3~!-on 0Crl8Ni9Ti occluded cell in 0.5M NaCl solution. It was found that the corrosion rate of 0Crl8Ni9Ti in occluded solution decreased and that the open-circuit potentials moved in the positive direction with increase of [NO_3~-]_(bulk). When [NO_3~-]_(bulk)≥0.025M(50℃) or [NO_3~-]_(bulk)≥0.2M(90℃),a state of active-passive transition occurred inside occluded cell. When [NO_3~-]_(bulk)≥0.3M(50℃)or[NO_3~-]_(bulk)0. 5M(90℃),the passivating effect was greatly improved, namely, the passive region becoming larger, the critical anodie current density for passivity and passive dissolution rate decreased. The inhibition efficiency inside O. C. was more than 90％at the above-stated NO_3~- concentration. The addition of sufficient NO_3~- cancause the steel in occluded cell to become passive, so that O. C. C. can be retarded.
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