著者

土肥 信康 加藤 敏春 正木 征史

出版者

一般社団法人 表面技術協会

雑誌

金属表面技術 (ISSN:00260614)

巻号頁・発行日

vol.26, no.9, pp.411-415, 1975-09-01 (Released:2009-10-30)

参考文献数

10

被引用文献数

8 7

---

The inhibition effects and mechanism of benzotriazole (B.T.A.) on tarnishing and corrosion of silver were studied by means of potentiostatic polarization curves, differential capacity-electrode potential curves, and accelerated testings in H2S and SO2 atmospheres. It was recognized that B.T.A. had little inhibition effects in acidic solutions (pH 2.5), but had great effects in almost neutral solutions; because, B.T.A.-Ag complex was formed on the surface in anodic potential region, and B.T.A. was adsorbed on the surface with lone electron-pairs of N-atoms in cathodic potential region. Silver treated with B.T.A. had an enhanced resistance to tarnishing in H2S atmosphere. It was considered that the prevention would be due to the formation of stable B.T.A.-Ag film on the surface. The galvanic corrosion of silver-plated panels occurred in SO2 atmosphere, leading to the copper base owing to the presence of pores, was much more markedly inhibited by electrolytic treatment than immersion treatment in B.T.A. solution. It was found that the change in the surface coverage (θ) of B.T.A. treated copper conformed to Langmuir's adsorption formula expressed as follows: θ=Km/(1+Km), where K: adsorption constant and m: concentration of B.T.A. Then, the changes of K by immersion treatment and by electrolytic treatment were measured. As the results, a larger value of K was obtained by electrolytic treatment. Therefore, it was considered that the adsorption of B.T.A. on copper through pores became easier by electrolytic treatment.

著者

井上 博之 山川 宏二 近藤 哲也 正木 征史

出版者

The Surface Finishing Society of Japan

雑誌

表面技術 (ISSN:09151869)

巻号頁・発行日

vol.41, no.11, pp.1178-1180, 1990-11-01 (Released:2009-10-30)

参考文献数

8

被引用文献数

2 4

---

Silver deposits formed on copper substrates by replacement reactions show poor adhesion, and a silver film plated on such a deposit dose not adhere. Silver ion makes a highly stable complex with cyanide ion, so that in a silvercyanide solution, the activity of silver ion is very small. This is one of the reasons for the universal use of cyanide baths in the industrial silver plating.However, consideration of the difference between the values of the stability constants for the silver-iodide complex and for the copper-iodide complex suggest that the rate of replacement deposition of silver on the copper substrate in silver-potassium iodide solutions, might be comparatively low. To confirm this, the rate of replacement deposition of silver in a silver-potassium iodide solution (AgNO3 0.10mol/L, KI 2.00mol/L) and in a strike silver plating bath (AgCN 0.028mol/L, KCN 1.15mol/L) was estimated from the current density corresponding to the point of intersection of the anodic and the cathodic polarization curves. These estimated values were almost the same, and it is suggested that the silver-potassium iodide solution is not only a cyanide free silver plating bath capable of employing a copper substrate but a silver plating bath which requires no strike plating.