Evaluation of the thermal shock behaviour of tape cast ceramic substrates by means of lamp irradiation

Abstract

Thermal shock behaviour of tape-cast Y-PSZ is characterised by lamp irradiation, i.e. the generation of strong lateral temperature gradients in thin circular discs by rapid heating with a high power halogen lamp. The accuracy of the method could be strongly improved by coating the samples with a circular graphite spot in the disc centre. This remarkably reduces the elliptical distortion of the temperature profile due to the plane wound filament of the lamp. The time resolved in situ measurement of the temperature profile with a high speed thermal imaging system enables the calculation of the arising thermal stresses. The application of the maximum temperature in the disc centre at the moment of failure, T max, as an easily measurable thermal shock quality control parameter for industrial applications is demonstrated and the relation between T max and the thermal shock resistance parameter under plane stress conditions is discussed. The results are compared with ring-on-ring strength tests which show the same trend.