Method of the preparation of a ceramic cordierite powder sinterable at low temperatures, powder obtainable by the method and ceramic composition obtained by sintering the powder

摘要

The present invention relates to a ceramic powder of cordierite (2 MgO 2 Al ₂ O _3, 5 Si0 ₂₎ sintering at low temperature, characterized in that its composition is from 60 to 50% Si0 _2, 5 to 20% MgO and 20 40% AI ₂ 0 _3, and in that its specific surface is at least equal to 50 m ² / g, this powder having a sintering temperature below 1100 ° C.; The invention also relates to a powder of this preparation process, comprising preparing a mixed alcoholic solution of an aluminum and silicon salt, to prepare a solution of a soluble magnesium salt in alcohol, mixing the two solutions, adding to this solution a hydrolyzing agent in the form of weak base completely volatile, which leads to the formation of a gel, subjecting said gel to a first heat treatment at a temperature at most equal to 450 ° C, and subjecting said powder to a second heat treatment at a temperature between 450 ° C and 900 ° C.; By sintering can be carried out at a temperature below 950 ° C, the resultant powder leads to dielectric ceramic having a coefficient of expansion less than 1: 10- ^6BC-1, and a dielectric constant less than 5.