Prediction of strength based on defect analysis in Al₂O₃ ceramics via non-destructive and three-dimensional observation using optical coherence tomography

Abstract

Non-destructive analysis is important in terms of improving the reliability of ceramics. In the study, the internal structure of Al₂O₃ ceramics with artificial pores was observed via optical coherence tomography (OCT). The OCT observation was performed on a surface perpendicular to the tensile surface of the specimen. The spherical pores were successfully observed via OCT. The strength and fracture origin were predicted from the size and position of the observed pores. The lowest predicted strength (which is realized as the strength of the specimen) was in agreement with the bending strength obtained via three-point bending tests. The actual fracture origin observed by scanning electron microscope was also the same as that predicted via the OCT observation. Thus, the results indicated that the nondestructive testing via OCT was useful in terms of predicting the strength and fracture origin of ceramics.