The damage assessment of thermally shocked high density, high purity aluminum oxide

The traditional approach to thermal shock testing in brittle materials has been to determine the temperature difference required to nucleate cracks in these materials. Recent work has indicated that the degree of damage after crack nucleation should be an additional consideration. The degree of damage resulting from cooling thermal shocks has been the primary consideration of the present work. Test specimens of two geometries: long, solid rods and short, solid cylinders were quenched from selected temperatures into ice water. The degree of damage was determined through strength measurements and sonic damping analysis. Initial damage occurred at a temperature difference above 150⁰C; this was characterized by significant decreases in strength, increases in strength data dispersion, and changes in sonic behavior. A model has been employed to predict degree of damage using crack depths as a criteria. Good agreement is seen between the predicted crack depths and observed crack depths at low temperature differences. At higher temperature differences, crack densities increase, and crack interactions affect the agreement between the predicted crack depths and those observed --Abstract, page ii