کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1660691 1008409 2008 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Synergistic corrosion protection for galvanized steel by phosphating and sodium silicate post-sealing
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد فناوری نانو (نانو تکنولوژی)
پیش نمایش صفحه اول مقاله
Synergistic corrosion protection for galvanized steel by phosphating and sodium silicate post-sealing
چکیده انگلیسی

To improve the corrosion resistance of phosphate coatings, the phosphated hot-dip galvanized (HDG) sheets were post-sealed with sodium silicate (water glass) solutions. The morphology and chemical composition of the composite coatings was analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The effect of sodium silicate post-sealing treatment on the corrosion behaviors of phosphate coatings was investigated by neutral spray salt (NSS) tests and electrochemical measurements. The results show that after the silicate post-treatment the pores among zinc phosphate crystals are sealed with the films containing Si, P, O and Zn, leading to the formation of the continuous composite coatings on the surface of HDG steel. The corrosion resistance of the composite coatings depending on concentration of sodium silicate and post-sealing time is greatly improved by the silicate post-treatment. The optimum concentration of silicate and post-sealing time are 5 g/L and 10 min, respectively. Both the anodic and cathodic processes of zinc corrosion on the samples are suppressed conspicuously, and the synergistic protection effect of the single phosphate coatings and the single silicate films is evident. Moreover, the low frequency inductive loop in electrochemical impedance spectroscopy (EIS) is disappeared and the electrochemical impedance values are increased for more than one order of magnitude. The corrosion protection of the composite coatings is comparable to that provided by the chromic acid post-treatment.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Surface and Coatings Technology - Volume 202, Issue 9, 1 February 2008, Pages 1831–1838
نویسندگان
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