連続蒸着試験設備により作製した蒸着亜鉛合金めっき鋼板の皮膜構造と耐食性(気相めっき)(<特集>表面処理)

概要

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New zinc alloy coated steel sheets have been developed by continuous vapor deposition apparatus. In a deposition chamber, zinc and alloying metal were evaporated individually by Electron-Beam (EB) irradiation, and were deposited on steel strip continuously. Some properties of Zn-Al, Zn-Cr, Zn-Mg, Zn-Ni and Zn-Ti alloy coated steel sheets were investigated. Crystal orientation of these coatings was affected by alloying metals. Depth profiles of alloy composition in Zn-Al and Zn-Mg coatings are almost uniform. The other coatings had double-layered structure, composed of an intermetallic compound layer and a zinc rich layer. The intermetallic compound phases were not the same as those shown in a equilibrium phase diagram for binary alloys. Corrosion resistance of Zn-Mg alloy coated steel without painting is excellent in salt spray test. Corrosion product layer of this coating consists of only ZnCl_2・4Zn(OH)_2 without ZnO and c-axis of hcp structure of ZnCl_2・4Zn(OH)_2 was parallel to the direction of the film growth. Mg ion dissolved from the coating during corrosion seemed to play a role to form this corrosion product layer.
社団法人日本鉄鋼協会の論文
1991-07-01