Reliability assessment in stress analysis of alumina/zirconia composites using Raman and fluorescence piezo-spectroscopy

摘要

Alumina/zirconia composites have found practical application as structural and functional materials because of their superior mechanical strength characteristics. However, the micromechanical origin of such a high strength yet remains unclear and new characterization tools, capable to give deeper physical insight into the observed strengthening phenomenon, need to be developed on a microscopic scale. Raman and fluorescence piezo-spectroscopies can be used as valuable tools for microscopic stress analysis in ceramic materials and appear to possess a suitable spatial resolution for properly assessing the micromechanical behavior of alumina/zirconia composites. In this paper, we evaluate quantitatively the stress dependence of the spectroscopic shift of Raman bands of zirconia and fluorescence bands of alumina, when these two phases are mixed and sintered with different volume fractions, to form dense composite materials. We address here the reliability of stress measurements in these composites by judging from the maximum error involved in the assessment of a known elastic stress field in a bending bar. An explanation is given of the spectroscopic reasons leading to such error and a method proposed to minimize it.