Photoacoustic thermal characterization of electrical porcelains: Effect ofalumina additions on thermal diffusivity and elastic constants

The open-photoacoustic-cell technique to measure thermal diffusivity is des cribed in detail. We have applied it to the measurement of thermal diffusiv ity of porcelain samples with four different alumina additions in the range 0-15 wt% and fired at four temperatures in the range 1270-1350 degrees C. Thermal diffusivity is shown to vary from 4.1x10(-7) m(2)s(-1) for a classi cal triaxial porcelain to 6.4x10(-7) m(2)s(-1) for 15wt% alumina addition m ade mainly at the expense of quartz when the firing temperature was 1325 de grees C. The values of thermal diffusivity are found to be well correlated with the values of the shear and Young's modulus. Good correlation was also observed among the measured values far thermal diffusivity and those for d ensity and mullite to quartz ratio. We conclude that the open-photoacoustic -cell technique has enough sensitivity to defect small changes in compositi on and microstructure of materials as complex as porcelains. (C) 1999 Elsev ier Science Limited All rights reserved.