Centre National De La Recherche Scientifique

Pechiney Recherche Groupement D'interet Economique

Jean-Claude Bernier

Paul J Poix

Jean-Louis Guille

Claude Drapier

Serge Vilminot

Jean L Rehspringer

Jean-Luc Rehspringer

Veronique Oliver

Gabriel G Vilmin

The invention concerns a process for preparing titanates and zirconates respectively of formulas MTiO.sub.3 and MZrO.sub.3 where M is Ba.sup.2+, Sr.sup.2+, Ca.sup.2+, Pb.sup.2+ and Mg.sup.2+ to the exclusion of MgZro.sub.3, consisting of reacting an ester of formula M[H-(CH.sub.2).sub.n CO.sub.2 ].sub.2 where n=1-4 with the formula M'[O(CH.sub.2).sub.n CH.sub.2).sub.n CH.sub.3 ].sub.4 where M' is Ti or Zr bringing the reaction mixture to boil until the solvent is removed to yield a viscous translucent resin. The resin is cooled and further treated to obtain the desired product.

Process for preparing titanates and zirconates

The invention comprises a process for co-sintering of conductors of copper or copper-based alloy and a ceramic substrate, the substrate being produced from a ceramic powder of cordierite type, having a sintering temperature of lower than 950.degree. C. The process comprises the following steps:

Process for co-sintering conductors of copper or copper-base alloys and

The present invention relates to a cordierite (2MgO.2Al.sub.2 O.sub.3.5SiO.sub.2) type ceramic powder sintering at low-temperature defined in that its composition is: 60 to 50% SiO.sub.2, 5 to 20% MgO and 20 to 40% Al.sub.2 O.sub.3, and in that its specific surface area is not less than 50 m.sup.2 /g, this powder having a fritting temperature of less than 1,100.degree. C. The invention also relates to a process for the preparation of this powder, which consists in preparing a mixed alcoholic solution of an aluminum and silicon salt, in preparing a solution of an alcohol-soluble magnesium salt, in mixing the two solutions, in padding a hydrolyzing agent in the form of a totally volatile weak base to the solution, which leads to the formation of a gel, in subjecting the said gel to a first thermal treatment at a temperature not exceeding 450.degree. C., and in subjecting the said powder to a second thermal treatment at a temperature of between 450.degree. C. and 900.degree. C. By a sintering which may be carried out at a temperature lower than 950.degree. C., the powder obtained leads to dielectric ceramics which have a coefficient of expansion less than 1.10.sup.-6 C.sup.-1, and a dielectric constant less than 5.

Low-temperature sinterable cordierite type ceramic powder, preparation

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Lingolsheim, France

Jean-Claude Bernier