PRODUCT COMPRISING AN ORIENTED FUNCTION AND PROCESS FOR OBTAINING SAME

摘要

Preparation of a slip including more than 4% and less than 50% of ceramic particles and including more than 1% of orientable ceramic particles made of a material including an oriented function, as volume percentage on the basis of the set of ceramic particles, wherein the fraction of non-orientable ceramic particles has a median length less than ten times the median length of the orientable ceramic particles if the set of ceramic particles includes less than 80%, as volume percentage, of orientable ceramic particles, oriented freezing of the slip by movement of a solidification front at a speed less than the speed of encapsulation of the ceramic particles; elimination of the crystals of solidified liquid phase of said block, optionally, sintering.

主权项

1. Process for manufacturing a product, optionally sintered, said process comprising the following steps:
a) preparing a slip comprising an ensemble of ceramic particles in suspension in a liquid phase, the ensemble of ceramic particles representing more than 4% and less than 50% of the volume of the slip and comprising, in percentage by volume based on the ensemble of ceramic particles, more than 1% of orientable ceramic particles of a material with oriented function, the fraction of the nonorientable ceramic particles having a median length ten times less than the median length of the orientable ceramic particles L50 if the ensemble of ceramic particles comprises less than 80%, in percentage by volume, of orientable ceramic particles, b) optionally, pouring the slip into a mould and/or removing air bubbles contained in the slip, c) oriented freezing of the slip by displacement of a solidification front so as to form a block of frozen slip, the velocity Vp of the solidification front being less than the velocity of encapsulation of the ceramic particles Vc and adjusted so as to form crystals of solidified liquid phase separated by walls with an average thickness “e” greater than or equal to the average thickness of the orientable ceramic particles W150; d) optionally, removing said block from the mould, e) removal of the crystals of solidified liquid phase from said block, optionally removed from the mould, so as to obtain a macroporous preform, f) optionally, removal of binder from the macroporous preform obtained at the end of step e), g) optionally, sintering the macroporous preform so as to obtain a sintered product, this step g) being obligatory if, in step a), the amount of orientable ceramic particles of a material with oriented function is less than 80%, in percentage by volume based on the ensemble of the ceramic particles; h) optionally, machining and/or impregnation of said sintered product; the ceramic particles being replaceable, partially or completely, with equivalent amounts of precursors that are transformed into ceramic particles so as to obtain said ensemble of ceramic particles before step c), and/or the ceramic particles being replaceable, partially or completely, with equivalent amounts of particles of the same shape of a ceramic precursor that is transformed into ceramic in step f) or g), the form of the orientable particles being determined so that the orientation of the orientable particles under the effect of the freezing in step c) results, in the macroporous preform, in an intensity of said function which is variable in the direction under consideration.