Trivalent chromium conversion coating formation on aluminium

SURFACE & COATINGS TECHNOLOGY

卷:280

Article

Qi, J. -T.¹  Hashimoto, T.¹  Walton, J. R.¹  Zhou, X.¹  Skeldon, P.¹  Thompson, G. E.¹ 

[1] Univ Manchester, Sch Mat, Manchester M13 9PL, Lancs, England

关键词: Aluminium;    TEM;    RBS;    XPS;    Raman spectroscopy;    Trivalent chromium coating;   

DOI  :  10.1016/j.surfcoat.2015.09.024

来源: Elsevier

【 摘 要 】

The formation of a trivalent conversion coating on aluminium has been investigated using analytical electron microscopy, atomic force microscopy, ion beam analysis, glow discharge optical emission spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The coating is shown to comprise a chromium- and zirconium-rich outer layer and an aluminium-rich inner layer. Zirconium and chromium are present in chemical states consistent with ZrO2, ZrF4, Cr(OH)(3), Cr-2(SO4)(3), CrF3 and CrO3 or CrO42-. However, negligible amounts of Cr(VI) species occurred in coatings formed in de-aerated solution. Electrochemical impedance spectroscopy revealed that the inner layer provides the main corrosion protection during short-term tests in 0.1 M sodium sulphate solution at room temperature. (C) 2015 The Authors. Published by Elsevier B.V.

【 授权许可】

Free