In situ study of fracture mechanisms in advanced ceramics using fluorescence and Raman microprobe spectroscopy
✍ Scribed by Giuseppe Pezzotti
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 478 KB
- Volume
- 30
- Category
- Article
- ISSN
- 0377-0486
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✦ Synopsis
A procedure is described for the evaluation of the fracture behaviour of polycyrstalline ceramics using an in-situ stress analysis involving either fluorescence or Raman microprobe spectroscopy. The full details of the experimental set-up, calibration procedures and stress calculations are shown, and their reliability discussed in some detail. Stress maps were obtained along the wake of cracks stably propagated in six selected polycrystalline ceramics with representative microstructures. A conventional fracture mechanics assessment was concurrently performed to relate microscopic stress data to the macroscopic fracture resistance of the materials. It is demonstrated that the most effective toughening mechanism in polycrystalline ceramics takes place in the crack wake and arises from both elastic and frictional shielding tractions operated by crystallites which are left unfractured behind the crack tip.