Effect of TiO2 addition on the chemical durability of Bi2O3–SiO2–ZnO–B2O3 glass system

The effect of the substitution of ZnO for TiO2 on the chemical durability of Bi2O3–SiO2–ZnO–B2O3 glass coatings in hot acidic medium (0.1 N H2SO4 at 80 °C) for different times was studied. The thick films produced by a screen-printing method and heat treated at 700 °C/5 min were analyzed by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The glass from the Bi2O3–SiO2–ZnO–B2O3 system developed Zn2SiO4 and a glassy phase that were readily attacked by hot 0.1 N sulfuric acid, whereas the heat treated coating from the Bi2O3–SiO2–TiO2–ZnO–B2O3 system presented a finer microstructure with thin interconnected Bi4Ti3O12 crystals and a glassy phase more resistant to hot 0.1 N sulfuric acid attack etching.