Chemical stability of yttria doped zirconia membranes in acid and basic aqueous solutions: chemical properties, effect of annealing and ageing time

Corrosion resistance of 3Y–ZrO2 microfiltration membrane was evaluated at room temperature and 80°C in aqueous solutions of acids and bases. Chemical properties were investigated in order to explain the chemical attack and the effect of elemental dissolution on the phase transformation. Dissolution of yttria was detected in acid solutions of low pH except in HF solution. In the basic solutions, dissolution of Y and Zr was negligible. Silica dissolved both in acid and basic solutions. As a result of chemical reactions and dissolution of ions, pH after corrosion showed a shift to higher values in acid solutions and to lower values in basic solutions, indicating the amphoteric reactions in 3Y–ZrO2. Samples corroded in acid and basic solutions at 80°C were annealed at 1200°C after the corrosion test. Phase transformation was completely reversible in the samples tested in basic solutions. The sample in acid solution showed partial re-transformation of the monoclinic phase due to the dissolution of yttria. The effect of corrosion time was studied for aqueous solutions of HF and HCl.