Zirconoiate corrosion in dilute acidic and basic fluids at 180-700° C and 50 MPa

Corrosion of zirconolite in a closed system at elevated temperature and pressure for various fluid compositions has been investigated by several analytical techniques. Together with previous studies, the results indicate a weak corrosion below 250 C at 50 MPa. Above 400 C, secondary TiO{sub 2} phases crystallize in acidic and neutral fluids on the corroded surfaces and in near-surface pores. At 550 C and above, zirconolite starts to be replaced by perovskite and calzirtite in basic fluids. Results indicate that zirconolite is reasonably durable in acidic, neutral and basic fluids up to 500 C and 50 MPa which corresponds to deep borehole conditions.