SEDL / STP / STP1172-EB / STP24711S

Fracture Toughness Evaluation of Ceramic Bonds Using a Chevron-Notch Disk Specimen

Rosenfield, AR
Research leader and principal research scientist, Battelle Memorial Institute, Columbus, OH

Majumdar, BS
Research leader and principal research scientist, Battelle Memorial Institute, Columbus, OH

Pages: 11    Published: Jan 1992

Download this paper for $25 PDF (220K)          View License Agreement
Abstract

The chevron-notched diametrally compressed disk specimen has been used to measure the fracture toughness of zirconia/zirconia bonds and zirconia/nodular-cast-iron bonds. The data are reasonably consistent with experience obtained using monolithic ceramics. In particular, the strain energy release rate increases with increasing shear:tension ratio, and the opening-mode fracture toughness measured using the disks is generally within 20% of the value obtained with bend beams. However, the shear toughnesses of the bonds investigated are approximately 2.4 times the opening toughness, a ratio somewhat higher than that for monolithic ceramics. The high ratio can be attributed to rubbing of mutually opposed crack faces, deviation of the fracture plane into higher-toughness zirconia prior to instability for the ceramic/ceramic bonds, and shear of the braze-metal interlayer in the case of the metal/ceramic bonds.