MATETPRO - Matériaux et Procédés pour des Produits Performants

Alternative Sustainable Zirconia Technology (for glass melting) – ASZTech

Submission summary

The high quality level required by the new applications of glass (flat LCD, PDP screens,…), combined with the increase of the lifetime of glass furnaces implies the development of new high zirconia fused-cast refractories that are necessary for their production. One issue consists in developing new product compositions with modified dilatometric behaviour. The final goal is to increase the flexibility in the use of furnaces by limiting the joints openings and the residual deformations created at each cycle stop-restart of the furnace. The development of new products involves expansive trial-error methods, which justify the development of a numerical simulation of the thermomechanical behaviour of these materials, suitable for both processing of materials and warm-up of furnaces.

The proposed programme, ASZTech, is an extension of the NOREV project, already funded by ANR. The aim of this programme was to provide to Saint Gobain CREE numerical tools based on finite element calculations. These tools are currently used by the industrial partner, in particular to simulate the controlled cooling-down after casting, to increase the production efficiency. The influences of cooling conditions modifications can be simulated in order to improve the capacity of making complex shapes and the service quality of the final product. These models also allowed a better definition, for the glass maker, of recommendations for an improved service behaviour, particularly for the first warm-up of the furnace. These points are of prime importance to maintain Saint Gobain as a leader on the strongly increasing market of high zirconia fused-cast refractories and to maintain -or even increase- its activity in the Le Pontet site, generating hundreds of jobs.

If the models developed in the framework of NOREV programme can be considered as robust concerning the thermal aspects, they still presents two misses from the mechanical aspects: the consideration of the plasticity associated to the zirconia transformation from tetragonal to monoclinic and the validation of the prediction capability of the model to calculate realistic stresses. Previous studies revealed the major importance of the phase transformation for the processing of new products, that the model cannot yet take in consideration. This phenomenon was firstly considered as detrimental because of the associated volume increase of 4% and of the subsequent internal stresses in the material. But the transformation is also accompanied by a transformation-induced plasticity (TRIP) which can be beneficial for stress relaxation. Very few studies are available about the mechanical effects induced by the zirconia transformation, because the problem has been solved by the total or partial stabilisation of zirconia. Unfortunately, this solution does not work for fused-cast materials as well as for sintered materials.

The proposed programme aims four main targets:
1-To improve the existing model and to implement, from specific tests results, a realistic description of the zirconia transformation, including swelling and transformation-induced plasticity, for different compositions.
2-To analyse the microstructural deformation mechanisms associated to the transformation, with the aim of anticipate them and, if possible, to control them during the fabrication of new products.
3-To measure the internal stresses on specimens or actual blocks, for different cooling conditions, using various techniques.
4- To validate the model by comparing its previsions to mechanical tests results, to internal stresses measurements and to the behaviour of a block in an actual glass furnace.

Project coordination

Michel BOUSSUGE (ARMINES Centre des Matériaux de MINES ParisTech) – michel.boussuge@mines-paristech.fr

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

ARMINES CdM ARMINES Centre des Matériaux de MINES ParisTech
SPCTS Laboratoire de Science des Procédés Céramique et Traitement de Surfaces
PIMM Procédés et Ingénierie en Mécanique et Matériaux
LEM3 Laboratoire d'Etude des Microstructures et de Mécanique des Matériaux
SG CREE Saint Gobain CREE, Centre d'Etudes et de Recherches Européen
MGSA Mistras Group SA
PIMM Laboratoire PIMM

Help of the ANR 1,044,267 euros
Beginning and duration of the scientific project: March 2013 - 48 Months

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