Micromechanics applied to the thermal shock behavior of refractory ceramics
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- 作者：Schmitt ; N. ; Burr ; A. ; Berthaud ; Y. ; Poirier ; J.
- 关键词：Thermal shock ; Multi-scale analyses ; Micromechanics ; Refractories ; Finite element computations
- 刊名：Mechanics of Materials
- 出版年：2002
- 出版时间：November, 2002
- 年：2002
- 卷：34
- 期：11
- 页码：725-747
- 全文大小：930 K
文摘
Oxides–carbon refractories are ceramics with a complex microstructure due to the variety of components present in the composition: namely, oxide aggregates and metallic additions, microcracks, porosity and a continuous carbon phase. The main aim of this work is to highlight the role of each component of a refractory subjected to severe thermal loading through the use of micromechanics. First, a multi-scale generalized self-consistent scheme (GSCS) is used to predict the macroscopic thermoelastic behavior of the refractory. Experiments on two-component specimens are performed to determine, through an inverse analysis, the properties of some components that were difficult to collect or to measure directly. The micromechanical model is validated by comparison with experimental data. Second, a microthermomechanical analysis is used to study the behavior of brittle two-phase ceramics subjected to thermal shock. A macroscopic fracture criterion is proposed that accounts for local failure mechanisms. This approach allows one to improve the classical thermal shock criteria for fracture initiation by accounting for some mechanisms of local failure in tension and the heterogeneity of the microstructure of the material. Third, this approach is used to predict the material degradation of a submerged nozzle subjected to high thermal loads. Finite element computations permit us to understand the contribution of the heterogeneity of the material to the resistance to damage of the part and to compare this approach with the prediction of classical thermal shock criteria.