Self-Cleaning Coatings on Tiles and Bricks
Ali Chour*, Ali Boussi, Pramod Koshy1, Cathy Inglis2, Takafumi Numata2, and
Charles Christopher Sorrell1
1School of Materials Science and Engineering, The University of New South Wales,
Sydney, NSW 2052, Australia;
2Brickworks Ltd., 738-780 Wallgrove Road, Horsely Park, NSW 2175, Australia;
*Email: actools@hotmail.co.uk
A sol-gel and aerosol spraying method was used to produce films of photocatalytic
TiO2 on bricks and terra cotta tiles. Solutions of titanium tetra-isopropoxide and
propanol were added to a dilute solution of nitric acid, refluxed, cooled, sprayed onto
the structural clay substrates at different thicknesses, and then annealed at various
temperatures up to 275°C. The morphological, mineralogical, and photocatalytic
properties of the coated samples then were assessed by scanning electron
microscopy/profilometry, X-ray diffraction/laser Raman microspectroscopy, and
methylene blue decomposition/UV-VIS spectrophotometry, respectively. The results
indicate that films annealed at as low as 100°C are photoactive but that optimisation
is a compromise between TiO2 recrystallisation (requiring higher annealing
temperatures) and silicon contamination (requiring lower annealing temperatures).