Comments on “Thermal shock resistance of yttria-stabilized zirconia with Palmqvist indentation cracks” by G. Fargas, D. Casellas, L. Llanes, M. Anglada [J. Eur. Ceram. Soc. 23 (2003) 107–114]

In a recent paper, Fargas et al. [Fargas, G., Casellas, D., Llanes, L. and Anglada, M., Thermal shock resistance of yttria-stabilized zirconia with Palmqvist indentation cracks. J. Eur. Ceram. Soc., 2003, 23, 107–114] make use of the Vickers indentation technique to characterise the thermal shock resistance of brittle materials exhibiting the Palmqvist indentation crack system. They claim that their approach can provide a measurement of Hasselmanʹs R⁗ thermal shock resistance parameter. It is here demonstrated that the obtained parameter is in fact different from R⁗. In parallel, it is shown that a previously developed approach, which is both consistent with the concepts of R⁗ and of the critical quenching temperature difference, ΔTC, can be used in the case of the Y-TZP ceramics of Fargas et al. This approach also allows an estimation of the maximum thermal stresses and of the coefficient of heat transfer at the fluid–solid interface as a function of the quenching temperature difference.