著者

乾 忠孝

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.8, no.7, pp.224-228, 1957-11-30 (Released:2009-10-30)

参考文献数

1

被引用文献数

1

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The mechanism of tungsten plating was investigated and the following results were obtained.1) The decomposition potential of tungsten in Na2WO4 solution is more negative than that of hydrogen, and its accurate decomposition potential could not be obtained from its current density potential curves. Of course, its decomposition potential differs according to the kind of cathodic metals.2) In the constant current density electrolysis, the cathodic potential is elevated with the progress of the electrolysis.3) In the constant potential electrolysis (e.g. 0.124V for Pt-W poles), a beautiful deposition of whitish grey metalic luster is obtained, with a little higher potential (e.g. 0.184V for Pt-W poles) a reddish brown metalic luster, and with a much higher potential black and spongy. With the lower potential, nothing is obtained but the generation of hydrogen.4) By the electron diffraction analysis, it is found that the whitish grey metalic deposition is chiefly composed of W-oxide (not WO2 or WO3) with a little metalic tungsten.5) When the Na2WO4 solution is electrolised, the tungsten becomes special cation of its oxide. When the solution is electrolysed with constant cathodic potential, the tungsten is regularly obtained as metalic deposition on the cathode. This deposition is chiefly composed of lower oxide tungsten (such as WO) containing a little tungsten. So, the resistance increases and the potential is elevated with the progress of electrolysis.As the potential is gradually elevated, the deposition grows rich in higher oxide and finally becomes to be spongy.After all, it might be concluded that, in order to obtain thick deposition from Na2WO4 solution, the amount of metallic ions in the solution is to be restricted and hydrogen ions increased, or some other reducing regents more powerful than hydrogen are to be used, or the alloy-plating is to be applyed.