Weibull distribution of the fracture strength of 99% alumina ceramic reshaped by cold isostatic pressing

The mechanical reliabilities of 99% alumina ceramics preformed by dry pressing using various pressures and reshaped by cold isostatic pressing (CIP) at 150MPa are investigated using the maximum likelihood method for the estimation of the Weibull parameters of the results. The results indicate that among the various values of dry pressing and sintering temperatures applied, a maximum Weibull modulus of 13.9974 and high reliability were attained for 75MPa dry pressing followed by subsequent 150MPa cold isostatic pressing (CIP) and a 1580°C sintering temperature. In addition, excessive preforming pressure caused dangerous flaws, called hardening defects, which were not repaired automatically by the CIP and sintering process, thus acting as a source of fracture and reducing the reliability of the specimen strength.