Phase transformation of stabilised zirconia in water and 1.0 M LiOH

The phase transformation of stabilised zirconia was studied after exposure to water and lithiated (1 M LiOH) water for 3 days at 400 degreesC, with th e aim to evaluate a proposed reason for the enhanced Zircaloy corrosion obs erved in the presence of lithium hydroxide. Three different tetragonal zirc onia samples were investigated, stabilised by addition of yttrium, cerium a nd by small crystallite size, respectively. One stabilised cubic zirconia s ample, with addition of calcium, was also included in the investigation. Th e corrosion test was performed in mini autoclaves and the crystal structure of the material, before and after the autoclave test, was characterised wi th X-ray diffraction.. For the three zirconia versions with tetragonal phas e, a majority of the material transformed to monoclinic phase in both envir onments, i.e., the transformation rate was found to be independent of the p resence of lithium hydroxide. The fraction transformed to monoclinic zircon ia was about 63% for size-stabilised sample and 84-94% for the yttria- and cerium-stabilised zirconia, while the cubic zirconia was unaffected by the corrosion test. Based on our result no evidence of preferential dissolution of stabilised zirconia is found in LiOH solution, compared to test in pure water. (C) 2001 Elsevier Science B.V. All rights reserved.