An efficient protection of stainless steel against corrosion:: Combination of a conversion layer and titanium dioxide deposit

SURFACE & COATINGS TECHNOLOGY

卷:202

Article

Bamoulid, L.¹  Maurette, M. -T.²  De Caro, D.³  Guenbour, A.⁴  Ben Bachir, A.⁴  Aries, L.¹  El Hajjaji, S.⁴  Benoit-Marquie, F.²  Ansart, F.¹ 

[1] Univ Toulouse 3, CIRIMAT, F-31062 Toulouse 4, France

[2] Univ Toulouse 3, Lab IMRCP, Grp POM, F-31062 Toulouse 4, France

[3] Chim Coordinat Lab, F-31400 Toulouse, France

[4] Fac Sci Rabat, Lab Electrochim Corros, Dept Chim, Rabat, Morocco

关键词: TiO2 coatings;    stainless steel;    corrosion protection;    conversion layer;    sol-gel;   

DOI  :  10.1016/j.surfcoat.2008.05.011

来源: Elsevier

【 摘 要 】

In the present work, a novel process has been developed to improve the corrosion properties of ferritic stainless steels. Titanium oxide coatings have been deposited onto stainless steel by sol-gel process after a pre-functionalization of the substrate in a conversion bath. Gel titania was prepared by hydrolysis of a titanium butoxide through a sol-gel process. Duplex systems conversion layer/uniform TiO2 coating have been prepared on stainless steels using a dipping technique and thermal post-treatments at 450 degrees C. The preparation of sol-gel coatings with specific chemical functions offers tailoring of their structure, texture and thickness and allows the fabrication of large coatings. The morphology and structure of the coatings were analysed using scanning electron microscopy with field effect gun (SEM-FEG), Mass spectroscopy of secondary ions (SIMS) and X-ray diffraction (XRD). The anticorrosion performances and the ageing effects of the coatings have been evaluated in neutral and aggressive media by using several normalized tests. The results show that the conversion layer was not sufficient to protect steel but sol-gel TiO2 coatings, anchored on the metal substrate via the conversion layer, show good adhesion with the substrate and act as a very efficient protective barrier against corrosion. So, duplex layers with Ti02 nanoparticle coatings on steels exhibit an excellent corrosion resistance due to a ceramic protective barrier on metal surface. Analysis of the data indicates that the films act as geometric blocking layers against exposure to the corrosive media and increase drastically the lifetime of the substrate. (c) 2008 Elsevier B.V. All rights reserved.

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