EFFECTS OF GRAIN-SIZE AND SPECIMEN GEOMETRY ON THE TRANSFORMATION ANDR-CURVE BEHAVIOR OF 9CE-TZP CERAMICS

Transformation and R-curve behaviour have been investigated in 9 mol % Ce-TZP ceramics with different grain sizes. Both single-edge notched beam and short double-cantilever beam specimens were tested to measure the crack-resistance curves. The size and shape of the transformation zone not only depend on grain size, but are also strongly influenced by the specimen geometry. This different transformation behaviour has led to different crack-resistance curves. These experimental results a re discussed in terms of the thermodynamics of transformation, the eff ect of autocatalytic transformation, and fracture mechanics.