This paper reports a new approach to the strengthdefectrelationship for ceramics with an alumina ceramics as a modelmaterial. Optical microscopy of transmisaion mode was applied tocharacterize defects in alumina ceraniics. This method is superior toany other methods in collecting deiailed information on large defectsin ceramics. The bulk examination on thinned specimen is crucial fordetecting few relatively large defects, one of which could behave asa potential fracture origin. A distribution curve is constructed forthe defect sizes and their concentrations. This curve is applied toestimate the strength variation of the ceramics through the fracturemechamcs. The estimated strength distribution was compared with theresults of direct measurement to detemine the relationship betweenthe fracture strength and the defect size. The defect sizedistribuiion can successfully explain the strength distribution ofthe ceramics.
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