Title: ACOUSTIC EMISSION STUDY OF MICROCRACKING IN WHITEWARES

Abstract:
Whiteware ceramics contain a glassy phase and several crystalline phases. Differences in contraction characteristics and, in some systems, phase transitions produce residual stresses during cooling after sintering that, in turn, produce microcracks. In this study, acoustic emission was monitored during cooling of whiteware specimens to detect microcracks as they formed. Acoustic signals were transmitted from the specimen to the transducer using an acoustic waveguide in contact with the specimen. Different commercial whiteware compositions and different cooling schedules were investigated. Little acoustic activity occurs until the temperature falls below about 570° C. Influences of composition and cooling schedules on acoustic activity, i.e., on microcracking, will be presented. The effectiveness of different ways of presenting and analyzing acoustic emission data will be discussed (e.g., hits, energy, frequency spectra, etc.). Results of post-test microscopy will also be shown.
(Ref. SXVIII-021-97)

Source: NDE of Ceramics '97 May 4-7, Symposium on Nondestructive Evaluation of Ceramics at the American Ceramic Society 99th Annual Meeting, Cincinnati, Ohio.
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