Fractographic Analysis of Ceramic Materials Tested Using the Diametral Compression Test
J Swab, George D. Quinn
The diametral compression (or Brazilian disk) test is a useful method for determining the tensile strength of ceramic materials. This test method has been utilized periodically over the past fifty years. The state of stress has been confirmed by theory of elasticity, finite element analysis, and photoelasticity studies. The resultant findings are remarkably consistent and in excellent agreement with the classical analysis by Hertz. In all cases there is a convergence of the stress solutions everywhere in the disk except in the immediate vicinity of the loading points. Strength values determined by the diametral compression test sometimes are comparable to flexure strengths, but in many instances are not. A critical missing link has been fractographic analysis which is usually limited to the examination of macroscopic crack branching patterns. Characterization of the fracture origins is extremely rare. The present study compares the strength-limiting flaw population highlighted by diametral compression and flexure tests for a yttria tetragonal zirconia polycrystal (Y-TZP) material.