Contact damage behavior of microstructurally tailored Yb-SiAlON ceramics under a spherical indenter was examined. Environmental scanning electron microscopy and optical microscopy were used to characterize the Hertzian contact damage. Four different microstructures with different α-SiAlON contents and grain morphology were evaluated for initiation of ring cracking. Onset of cracking was interrogated using acoustic emission spectroscopy and correlated to elastic failure models. Results indicated that a finer grain size distribution lead to a higher characteristic strength. From this study it was concluded that a fine grain size distribution is needed for high Hertzian contact strength.
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