防止银器文物变色的唑系复合缓蚀剂——I.缓蚀剂成膜处理工艺与防变色性能的评定

Azoles as Composite Corrosion Inhibitor for Anti tarnishing of Silver Antiques I. Process of the Inhibition Film Formation and Assessment of Its Anti tarnishing Abilities

:通过按正交法设计的紫外光照曝露等加速大气腐蚀实验 ,研究了用于防止银变色的唑系复合缓蚀剂成膜处理的工艺 ,并评定其对模拟文物银试片的防变色性能。采用极化曲线和交流阻抗Nyquist图 ,讨论了防变色作用的电化学机理。实验结果表明 ,缓蚀剂 PMTA、MBI和 MBO具有较好的协同作用 ,银试片在 5 0°C、p H 3.0、组分 MBO∶ PMTA∶ MBI为 1∶ 1 .7∶ 3(摩尔比 )、复合缓蚀剂浓度为 0 .0 1 89mol/L的溶液中 4h成膜处理后 ,经 48h硫华气氛和 36h紫外光曝露腐蚀实验 ,无色斑出现 。

The inhibition film forming process of the azoles as composite corrosion inhibitor for anti tarnishing of silver antiques was studied. Under UV light exposure and in other accelerated atmospheric corrosion tests, its tarnish prevention abilities were assessed with silver analogous antiques coupons. The polarization curve and Nyquist plots of electrochemical impedance spectrum were used to discuss the anti tarnishing mechanism of the corrosion inhibition film formed on the silver surface. The test results show a significant synergistic effect among corrosion inhibitors MBO, MBI and PMTA. The optimum process condition is screeded out: MBO∶PMTA∶MBI 1∶1.7∶3 (mole ratio), total concentration of composite inhibitor in solution 0.018 9 mol/L, pH 3.0, treatment temperature 50°C and pretreatment time 4h. Treated by this process, silver surface keeps clean and bright without appearance of any spot after 48h sulfur flower test or 36h UV light exposure corrosion test, and the anti tarnishing capability of the coupon is improved obviously.