Finite element simulation of ceramic deformation during sintering

Abstract : The control of the deformation of ceramic parts during the sintering process is essential, in order to avoid post-treatment and subsequent machining which increase the production costs. The procedure for obtaining the desired form after sintering is usually carried out by trial and error. An alternative to this costly approach is the prediction of shape instabilities during sintering by finite element simulation. With this aim, constitutive models have to be developed, taking into account the different deformation mechanisms induced by sintering. These phenomenological constitutive models use different material parameters which must be determined by experiment. This thesis aims to propose a methodology for modelling the deformation of ceramics during sintering. This methodology consists in experimental analysis of densification and pyroplastic behaviour of ceramics, developing a phenomenological constitutive model and material parameters identification. Two different materials have been studied: 1. A porcelain manufactured by slip casting process: Although slip casting process has been used for many years, it involves some technical problems that hinder the development of innovative products. Anisotropic deformation during sintering of slip cast parts is one of these problems. This behaviour is related to the rheological properties of the slurry and the orientation of anisotropic particles in the green part. An anisotropic constitutive model of sintering has been developed in order to predict the deformation of slip cast porcelain during firing process. 2. Ceramic cores made by injection moulding and used for investment casting of superalloys: Thermomechanical behaviour of zircon-silica cores has been studied by dilatometry and sinter-bending tests. The technical specificity of these materials is their low shrinkage during sintering process. This behavior is related to the crystallization of silica at high temperature. The crystallization inhibits the viscous flow and stops sintering shrinkage. A constitutive model predicting this behaviour is also proposed. These constitutive models have been implemented in the ”Zset” finite element program. After identifying the model parameters, the finite element numerical simulation has been performed on representative parts. Finally, the sensitivity of numerical results to mechanical parameters of an isotropic sintering model is analysed using a model reduction approach.
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  • HAL Id : tel-01085057, version 1

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Bahram Sarbandi. Finite element simulation of ceramic deformation during sintering. Mechanics of materials [physics.class-ph]. Ecole Nationale Supérieure des Mines de Paris, 2011. English. ⟨NNT : 2011ENMP0112⟩. ⟨tel-01085057⟩

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