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DEVELOPMENT OF ZINC ALLOY COATED STEEL SHEET FOR THE NEXT GENERATION

下一代锌合金涂层钢板的开发

基本信息

批准号：
09555217
负责人：
FUKUSHIMA Hisaaki
金额：
$ 8.13万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09555217/
关键词：
Steel Sheet Zinc Chromium PEG pH Hydroxide polarization Electrodeposition メタノール

项目摘要

We have been investigated the electrodeposition behaviors of Zn-Cr allots from sulfate baths, which is expected as the surface finishing method of steel in the next generation. The results are as follows :Cr was codeposited with Zn at highly current density in both PEG-free and PEG containing baths. However, PEG made it possible to reduce CrィイD13+ィエD1 to metallic state, and Cr existed in the state of CrィイD13+ィエD1 hydroxide in the deposits obtained from PEG-free bath. The chromium content in the deposits increased with an increase in the concentration and the molecular weight of PEG. The addition of PEG with molecular weight higher than #1540 permitted the deposition of zinc-chromium alloys of smooth and lustrous surfaces, while no deposits containing metallic chromium were obtained in the PEG-free baths and the baths containing PEG with lower molecular weight.Cathode potential of polarization curve shifted to less-noble direction by adding PEG to bath. The cathode potential was shifted to less positive direction with an increase in the concentration and molecular weight of PEG. Therefore, PEG inhibits the zinc deposition by absorbing on the cathode, and thus making it possible to attain the deposition potential of metallic chromium.The pH at cathode surface increased up to about pH4 during electrolysis. By identification of the hydrolysis products, it was expected that the hydroxides of Cr and Zn formed simultaneously in this cathode region. In Zn-Cr alloy baths containing PEG, the alloys were produced by discharging from the composite oxide of Zn and Cr formed by pH rising at cathode surface. Therefore, it seemed that PEG acts as a polarizer, which makes the cathode potential shift enough to discharge Cr Oxide to metallic state.

本文研究了锌铬合金在硫酸盐体系中的电沉积行为，这有望成为下一代钢铁表面处理方法。结果如下：在无PEG和含PEG的镀液中，在高电流密度下，Cr与Zn共沉积。而PEG使Cr（Ⅲ）D13+ Cr（Ⅲ）D1还原为金属态成为可能，在无PEG的镀液中，Cr以Cr（Ⅲ）D13+ Cr（Ⅲ）D1氢氧化物的形式存在。镀层中铬含量随PEG浓度和分子量的增加而增加。当PEG分子量大于1540时，锌铬合金镀层表面光滑光亮，而不含PEG和含低分子量PEG的锌铬合金镀层均未得到含金属铬的镀层;随着PEG浓度和分子量的增加，阴极电位向负移。因此，PEG通过吸附在阴极上抑制锌的沉积，从而使获得金属铬的沉积电位成为可能，电解过程中阴极表面的pH升高至约pH 4。通过对水解产物的鉴定，可以预期在该阴极区域同时形成Cr和Zn的氢氧化物。在含PEG的Zn-Cr合金镀液中，阴极表面pH升高形成的Zn和Cr复合氧化物放电生成合金。因此，PEG似乎起到极化器的作用，这使得阴极电位偏移足以将Cr氧化物放电到金属状态。