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Abstract

A new silane-phosphonic acid composite passivation coating process has been developed for the protection of electrogalvanized steel based on N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane(AAPTMS),γ-(2,3-epoxypropoxy)propyltrimethoxy-silane(GPTMS) and 1-hydroxy ethylidene-1,1-diphosphonic acid(HEDP).The results of X-ray photoelectron spectroscopy(XPS),Fourier transform infrared spectroscopy(FTIR),potentiodynamic polarization scan,electrochemical impedance spectroscopy(EIS) and neutral salt spray(NSS) tests indicated that the major structure of the prepared silane-phosphonic acid composite passivation coating consisted mainly of Si—O—Si and Si—O—P bonds.The area of white rust was not more than 5% of the total panal after 120 h NSS test,which could be compared favourably with the chromate colour passivation coating.However,the corrosion reaction on the anode of the silane-phosphonic acid composite passivation coating had more distinct diffusion control characteristics and belonged to the physical blocking mechanism.

Keywords

electrogalvanized steel, composite passivation, silane, phosphonic acid, corrosion resistance

Publication Date

2010-11-28

Online Available Date

2010-11-28

Revised Date

2010-11-28

Received Date

2010-11-28

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