著者

岡井 和久 中野 博昭

出版者

一般社団法人 表面技術協会

雑誌

表面技術 (ISSN:09151869)

巻号頁・発行日

vol.72, no.5, pp.295-302, 2021-05-01 (Released:2021-05-07)

参考文献数

27

被引用文献数

1

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This study investigated synergic effects of phosphoric acid(H3PO4), amino-propyltriethoxysilane(3-APS)and ammonium metavanadate(NH4VO3)in a conversion coating on electro-galvanized steel(EG)to clarify EG corrosion suppression by these substances.Results showed that the ratio of white rust during salt spray testing(SST)was lessened when a coating was formed with 3-APS and H3PO4. The phenomenon was explained: adding 3-APS into H3PO4 causes the decrease of corrosion resistance by suppressing salt water uptake in the coating because the coating itself became compact. Moreover, a coating formed with NH4VO3, 3-APS, and H3PO4 exhibited higher corrosion resistance in SST than a coating with 3-APS and H3PO4. Results show that NH4VO3 changed more into tetravalent or trivalent vanadium by oxidation reaction of zinc when the coating was formed together with 3-APS and H3PO4 on EG. These vanadium compounds in the coating were estimated as dissolved easily in the case in which salt water permeated into coating. The compounds were then deposited at the corroded area to reduce EG corrosion. These findings suggest that NH4VO3, 3-APS, and H3PO4 in the conversion coating contributed both to the high barrier and to self-protective effects of the coating.

著者

中野 博昭

出版者

一般社団法人 表面技術協会

雑誌

表面技術 (ISSN:09151869)

巻号頁・発行日

vol.70, no.8, pp.374-380, 2019-08-01 (Released:2020-02-01)

参考文献数

41

著者

中野 博昭 大上 悟 西野 友朗 福島 久哲 小林 繁夫

出版者

The Mining and Materials Processing Institute of Japan

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.128, no.10_11, pp.590-595, 2012-09-25 (Released:2013-10-28)

参考文献数

15

被引用文献数

3 5

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Electrodeposition of Cu was conducted in a synthetic electrorefining solution to investigate the effect of gelatin, thiourea and chloride ions on the polarization curve for Cu deposition, morphology, texture, surface roughness and the throwing power of the deposited Cu. In a solution containing both gelatin and chloride ions, the cathode potential for Cu deposition was significantly polarized at current densities above 200A/m2, while the thiourea depolarized the potential for Cu deposition at 200 to 1000A/m2. In a solution containing the three additives, i.e. gelatin, thiourea and chloride ions, the potential for Cu deposition was polarized at 500A/m2. It is supposed that the synergistic effect of gelatin and chloride ions on the polarization prevailed over the depolarization effect of thiourea. In the Cu deposited at initial stage, the chloride ions promoted the field-oriented texture with the orientation of direction. However, Cu deposited at initial stage from the solution containing gelatin, thiourea and chloride ions was composed of both the inclined texture type and the epitaxial growth type of crystals. The surface roughness and throwing power of the deposited Cu was most improved in the solution containing gelatin, thiourea and chloride ions, showing the synergistic effect of three additives. The thiourea had an effect on decreasing the surface roughness of the deposited Cu, and chloride ions improved the throwing power of Cu.

著者

孫 仁俊 中野 博昭 大上 悟 小林 繁夫 福島 久哲 堀田 善治

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.69, no.10, pp.892-898, 2005 (Released:2005-10-20)

参考文献数

13

被引用文献数

12 13

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The effect of equal-channel angular pressing (ECAP) on the pitting corrosion resistance of Al and Al-Mg alloy was investigated by means of polarization curves in solutions containing 300 ppm of Cl- and by surface analysis. The potentials for pitting corrosion of Al and Al-Mg alloy were evidently shifted to the noble direction by ECAP process, indicating that this process improves resistance to pitting corrosion. SEM observation revealed that the pitting corrosion occurred near the impurity precipitates and the size of impurity precipitated decreased with ECAP process. The time-dependence of corrosion potential and the polarization resistance determined by AC impedance technique suggested that the formation rate of Al oxide films was increased with ECAP process. The improvement in pitting corrosion resistance of Al and Al-Mg by ECAP seems to be attributable to the decrease in the size of impurity precipitates and the increase in the formation rate of Al oxide films.

著者

渡 健太 金子 祐輔 大上 悟 大原 秀樹 竹田 賢二 中野 博昭

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.133, no.10, pp.250-255, 2017-10-01 (Released:2017-10-31)

参考文献数

17

被引用文献数

1

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To elucidate the effect of solution composition on the passivation of anode in Cu electrorefining, the potentiodynamic polarization curves were measured by polarizing from -0.2 V versus NHE to 1.0 V using the potential sweep method at 1.0 mV·s−1. The diffusion coefficient was measured by rotating disc electrode method under the conditions of 50, 100, 150, 200, 250 and 300 revolutions per minute of disc electrode and polarizing from 0.34 V to -0.40 V at 10.0 mV·s−1. The critical current density for passivation and the passive current density decreased linearly with total concentration of SO4 in solution regardless of solution composition and the presence of impurities such as As3+,Sb3+ and Bi3+, showing the good correlation between the current density for passivation and the total concentration of SO4. The diffusion coefficient of Cu2+ ions decreased with total concentration of SO4 in solution. The increase in passivation with the total concentration of SO4 is attributed to both decreases in solubility of CuSO4 in electrolyte and the diffusion coefficient of Cu2+ ions. On the other hand, focusing on the effect of kinds of cation on the passivation, the harmful effect on the passivation was largest with Cu2+ ions, and was larger in the order with Li+,Ni2+ and Na+ ions, and was smallest with H+ ions. The diffusion coefficient of Cu2+ ions decreased most with Ni2+ ions, and decreased secondly with Li+ and Na+, and decreased least with H+ ions. The diffusion coefficient of Cu2+ ions decreased with increasing the viscosity of solution.

著者

徳重 晃大 森 康平 大上 悟 松島 寛 鈴木 一成 中野 博昭

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.133, no.7, pp.165-172, 2017-07-01 (Released:2017-07-21)

参考文献数

15

被引用文献数

5

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Cu electrolysis was performed using low-grade copper anode with purity 78.7 mass% at a anode current density of 200 A・m-2 in an unagitated sulfate solution containing 0.596 mol・dm-3 of Ni2+ ions as impurity at 60 ℃, and the structure of anode slime before and after passivation was analyzed. The highly-concentrated Sb, Pb and Ag were dispersed in copper anode before electrolysis. The passivation occurred at short time of 17.7 hours in the case of low-grade copper anode, and it occurred at shorter time of 11.4 hours in the solution containing Ni2+ ions as impurity. At normal dissolution of copper anode, copper parent phase dissolved in the form of dendrite and the framework of anode slime was composed of remained Cu-Ni-Sb-Sn-As compound. Cu2S and single phase of Ag and Pb were observed around this framework. At passivation, Cu, Ni and Sn dissolved from the slime framework composed of Cu-Ni-Sb-Sn-As compound, resulting in formation of Sb condensed phase. These Cu-Ni-Sb-Sn-As compound, Sb condensed phase, Cu2S compound around the slime framework, Ag and needle-shaped PbO dotted in the whole slime suppressed the diffusion of Cu2+ ions, as a result, CuSO4 was formed at interface between the slime and copper substrate. The passivation occurred at slime thickness of approximately 500μm in Ni2+-free solution, while it occurred at slime thickness of approximately 300μm in solution containing Ni2+ ions. This indicates that the passivation do not depend on only the thickness of slime. The thickness of CuSO4 formed at passivation in Ni2+-free solution was almost identical with that from the solution containing Ni2+ ions. In solution containing Ni2+ ions, the passivation occurred at less thickness of slime, showing that CuSO4 is easy to be formed in the vicinity of copper substrate due to decrease in solubility of CuSO4 and diffusion coefficient of Cu2+ ions.