Durability of mat glazes in hydrochloric acid solution

The influence of composition on durability of fast-fired mat raw glazes in hydrochloric acid was studied with several different methods. The appearance of the corroded glazes was classified according to a standardised visual method. The surface composition of the glaze was studied by SEM/EDXA. The crystalline phases in the glaze were identified by XRD. Changes in surface topography on micro-range were observed by AFM, while macro-range related changed were examined by a non-contact optical profiler. The concentration of dissolved ions in the acid solution after the corrosion test was analysed by ICPS. The results indicate that besides chemical composition also phase composition and surface morphology should be taken into account in corrosion studies of mat glazes. Corrosion of both amorphous and crystalline phases could be detected. The proportion of unreacted raw material in the glaze also strongly affected the corrosion behavior.