Acoustic emission characterization of kaolin-based clay ceramics

A series of ceramic materials such as kaolin, a pottery mixture and a 5% kaolin and 10% fly ash composite, were studied by acoustic emission (AE) during three-point bending after slip casting and sintering at various temperatures. Their acoustic behaviour has connected to structure development. AE activity was increased from kaolin to pottery mixture as a result of the developing a stronger structure with incorporation of a second phase in the matrix, while decreased in fly ash composites due to weakening of the structure and formation of cracks. In kaolin ceramics, there was a clear Kaiser effect, while pottery mixture and the kaolin–fly ash composites were acoustically active during the second loading and Felicity ratios were calculated.