  Atomic force microscopy (AFM) can be used to characterise several aspects of
the surface degradation and reinforcement mechanisms of zirconia based
ceramics, such as crack propagation, martensitic relief formation, grains
pull-out and transformation toughening. AFM can also be used to quantify
precisely the transformation and provide reliable parameters for long term
degradation prediction. In particular, the tetragonal to monoclinic (t-m) phase
transformation of zirconia has been the object of extensive investigations of
the last twenty years, and is now recognised as being of martensitic nature.
New strong evidences supporting the martensitic nature of the transformation
are reported here. These observations, considering their scale and precision,
are a new step toward the understanding of the t-m phase transformation of
zirconia and related degradation mechanisms.

Materials Science