Anticorrosion of WO&sub&3&/sub&-Modified TiO&sub&2&/sub& Thin Film Prepared by Peroxo Sol-Gel Method

摘要

The aim of this study was to develop a method to prepare WO_( 3 ) -TiO _( 2 ) film which has high anticorrosion property when it was coated on type 304 stainless steel. A series of WO _( 3 ) -modified TiO _( 2 ) sols were synthesized by peroxo-sol gel method using TiCl _( 4 ) and Na _( 2 ) WO _( 4 ) as the starting materials. TiCl _( 4 ) was converted to Ti(OH) _( 4 ) gel. H _( 2 ) O _( 2 ) and Na _( 2 ) WO _( 4 ) were added in Ti(OH) _( 4 ) solution and heated at 95 ° C. The WO _( 3 ) -TiO _( 2 ) sol was transparent, in neutral (pH~7) solution, stable suspension without surfactant, nano-crystallite and no annealing is needed after coating, and very stable for 2 years in stock. WO _( 3 ) -TiO _( 2 ) sol was formed with anatase crystalline structure. These sols were characterized by XRD, TEM, and XPS. The sol was used to coat on stainless steel 304 by dip-coating. The WO _( 3 ) -TiO _( 2 ) was anatase in structure as characterized by X-ray diffraction. There were no WO _( 3 ) XRD peaks in the WO _( 3 ) -TiO _( 2 ) sols, indicating that WO _( 3 ) particles were very small, possibly incorporating into TiO _( 2 ) structure, providing the amount of WO _( 3 ) was very small. The TiO _( 2 ) particles were rhombus shape. WO _( 3 ) -TiO _( 2 ) had smaller size area than pure TiO _( 2 ) . The SEM results showed that the film coated on the glass substrate was very uniform. All films were nonporous and dense films. Its hardness reached 2 H after drying at 100 ° C, and reached 5 H after annealing at 400 ° C. The WO _( 3 ) -TiO _( 2 ) film coated on 304 stainless steel had better anticorrosion capability than the unmodified TiO _( 2 ) film under UV light illumination. The optimum weight ratio of TiO _( 2 ) : WO _( 3 ) was 100:4.