塗膜の耐水密着性におよぼすりん酸塩皮膜の構造変化の影響

概要

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Relation between structure transformation of phosphate film formed in proportion to composition of phosphate solution and wet adhesion of paint has been investigated. Fine and dense phosphate film is formed by phosphate solution of high Ni^〓 concentration in Zn and Zn-Ni alloy electroplated steel sheet. At the same time, phosphate film becomes amorphous. Zn_3^PO_4)_2・4H_2O dehydrates to Zn_3(PO_4)_2・2H_2O with cathodic electrodeposition (C-ED) baking. Decrease of Zn_3(PO_4)_2・2H_2O and restoration of Zn_3(PO_4)_2・4H_2O are observed after water immersion, but restoration of Zn_3(PO_4)_2・4H_2O becomes lower in the case of phosphate solution of high Ni^〓 concentration. Wet adhesion of 3 coated sample is connected with restoration of Zn_3(PO_4)_2・4H_2O intensely and is very good in the case of lower restoration of Zn_3(PO_4)_2・4H_2O. After water immersion, new extractions have been observed on surface of phosphate film. Results of EDX analysis and electron diffractions on leprica to extract them have identified ZnO. In Zn and Zn-Ni alloy electroplated steel sheet, occurring ZnO becomes finer and less in proportion to increase of Ni^〓 concentration in phosphate solution. After wet adhesion test on 3 coated sample, ZnO has been detected by electron diffraction on extraction leprica from both exfoliated paint film and steel side.
社団法人日本鉄鋼協会の論文
1985-08-01