In situ measurements of frictional bridging stresses in alumina using fluorescence spectroscopy

Journal Article · Thu Jan 01 04:00:00 EST 1998 · Journal of the American Ceramic Society

DOI:https://doi.org/10.1111/j.1151-2916.1998.tb02312.x· OSTI ID:616216

Pezzotti, G; Maruyama, Ken; Nishida, Toshihiko ^[1]; Muraki, Naoki ^[2]

---

1. Kyoto Inst. of Tech. (Japan). Dept. of Materials
2. Toray Research Center, Inc., Otsu (Japan)

Fracture of a large-grained alumina polycrystal has been examined in situ by optical microscopy. Concurrently, local bridging stresses, as generated by friction or tension of unbroken ligaments in the wake of the crack path, were measured by piezospectroscopy. Stress measurements were performed both at fixed sites as a function of the external load and at a fixed external load along the crack profile. Frictional stresses were {approx} 50 MPa, while unbroken ligaments between the crack faces were found to support tensile stresses up to {approx} 100 MPa. The maximum bridging stress was dictated by the weak (intrinsic) interface bonding of the polycrystal. Average bridging stresses, either theoretically calculated from R-curve data or experimentally measured by piezospectroscopy on frictional/bridging sites, were similar. Such a circumstance enables them to explain the fracture behavior of polycrystalline alumina by considering crack-wake shielding as the main micromechanism contributing to toughening.

• Sponsoring Organization: USDOE
• OSTI ID: 616216
• Journal Information: Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 1 Vol. 81; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
CRACK PROPAGATION
FRACTURE MECHANICS
FRACTURE PROPERTIES
STRESSES