Atomic force microscopy study of the tetragonal to monoclinic transformation behaviour of silica doped yttria-stabilized zirconia

摘要

The tetragonal to monoclinic phase transformation of zirconia has been thesubject of extensive studies over the last 20 years [1-4]. The main features ofthe transformation have been identified and its martensitic nature is nowwidely recognised [5-8]. More specifically, the relevance of a nucleation andgrowth model to describe the transformation is widely accepted. Recent fractureepisodes [9] of zirconia hip joint heads were reported, failures related to thet-m transformation degradation. Among the materials solutions considered fordecreasing the sensitivity to t-m phase transformation, the possibility ofadding silica as a dopant appears as an appealing one. Previous studies haverevealed the beneficial effect of silica addition by the formation of a glassyphase at the grain boundaries and triple points. This glassy phase has beenproven to reduce the residual stresses level [10], slowing down thetransformation kinetics. Preliminary quantitative investigations by XRD haveshown these materials are less susceptible to transformation. However, themechanism by which the transformation propagated has still to be assessed.