DIP COATING OF TITANIUM ETHOXIDE SOLUTIONS

Titania coatings are prepared by dip coating anhydrous titanium ethoxi de solutions on glass substrates. Titanium ethoxide reacts with atmosp heric water during deposition and drying to form coatings with a varie ty of microstructures. Transparent gel layers are prepared by coating in dry nitrogen and then exposing the coating to humid atmosphere or u sing slow withdrawal rates. Hydrated titania particles form in coating s deposited in atmospheres with relative humidity levels greater than approximate to 15%. These coatings are typically composed of agglomera tes of small particles (approximate to 0.3 mu m); increases in substra te withdrawal rate and Ti ethoxide concentration in the solution bath lead to increases in thickness, particle size and extent of agglomerat ion. Particle aggregation is prevented by adding hydroxypropyl cellulo se (HPC) to the coating solution before deposition.