Societe Europeenne Des Produits Refractaires

Saint-gobain/norton Industrial Ceramics Corporation

Societe Europeene Des Produits Refractaires

Societe Europeen Des Produits Refractaires

Daniel Urffer

Joseph Recasens

Pierre Ferlanda

Christophe Bert

Yves Stefani

Edward Lilley

Bernard Cales

Marc Abouaf

This invention relates to a biojoint prosthesis comprising:

Hip joint prosthesis having a zirconia head and a ceramic cup

The invention relates to a refractory thermally-insulating component consisting essentially of refractory ceramic fibers which are mechanically combined with one another, the composition of which comprises at least 97.5% by weight of alumina, silica and zirconia in total, wherein:

Thermally-insulating components made of thermally-stabilized refractory

The invention relates to fused ceramic beads, which have the following chemical composition in % by weight on the basis of the oxides: 40 to 95% of ZrO.sub.2 and HfO.sub.2 ; at least one of Y.sub.2 O.sub.3 and CeO.sub.2, with the provisos that Y.sub.2 O.sub.3, when present, represents 0.1 to 10% and CeO.sub.2, when present, represents 1 to 25%, the total of Y.sub.2 O.sub.3 and CeO.sub.2 representing 0.1 to 25%; a quantity of SiO.sub.2 representing 10 to 45% of the composition when CeO.sub.2 is absent from the composition and 0.5 to 45% when CeO.sub.2 is present in the composition. Application to grinding and to dispersion in wet medium is provided.

Fused ceramic beads

Reactive derivatives of zirconium, are provided which are in the form of a pulverulent white, non-crystallized solid which is dry in appearance, and consist of metazironic acid, ZrO (OH).sub.2, accompanied by free or weakly bound water, some of the OH.sup.- ions being optionally replaced by halide ions. The ZrO.sub.2 content of these derivatives is from 60 to 92% by weight inclusive, the water content ranges from 3 to 40%, and the halide ion content can range up to approximately 5% by weight. The solid derivatives of the invention can be easily converted into usual reactive derivatives of zirconium by reaction with an aqueous solution of an acid.

Reactive derivative of zirconium and its preparation

A process for the preparation of improved zirconium oxides comprising A) providing a zirconium oxide which has been produced by thermal decomposition of zircon followed by chemical digestion of the resultant silicate phases, B) reacting the zirconium oxide at high temperature with an alkali metal hydroxide or carbonate so as to form an alkali metal zirconate, C) hydrolyzing the resultant alkali metal zirconate so as to produce a suspension of zirconium oxide hydrate in a concentrated solution of alkali metal hydroxide, D) separating the zirconium oxide hydrate from the concentrated solution and washing the zirconium oxide hydrate which has been isolated, and E) drying the zirconium oxide hydrate at a temperature in the range of from 110.degree. to 570.degree. C.

Reactive zirconium oxide and its preparation

A process for the preparation of zirconia hydrate from zirconia by reaction of the latter with solid sodium hydroxide at 550.degree.-1,400.degree. C. to form Na zirconate; hydrolysis of the latter to form a suspension of zirconia hydrate in aqueous sodium hydroxide; separation of most of the aqueous sodium hydroxide; treatment of the zirconia hydrate containing residual aqueous sodium hydroxide with an ammonium salt; and separation, washing and dewatering of the purified zirconia hydrate obtained. The zirconia hydrate can be used for the preparation of zirconium compounds.

Process for the manufacture of zirconium oxide hydrate from granular

The invention relates to the chemistry of zirconium. It relates particularly to a reactive zirconium oxide in the form of fine particles whose median diameter does not exceed 10 .mu.m, which has a structure chosen from the amorphous structure and the structure crystallized in the tetragonal form, the size of the elementary coherence regions in the latter case being between 10 and 30 nm, and which has a B.E.T. surface area of at least 30 m.sup.2 /g, and to a process for its preparation. Use in the field of ceramic materials.

The invention relates to ceramic articles. It relates to an article made of ceramic material produced by fusing and casting in a mold a composition based on alumina, zirconia, silica and an alkali metal oxide, said article consisting of crystalline corundum and zirconia phases and of a vitreous phase, said zirconia being substantially in monoclinic form from the core to the skin of said article, and having, in at least one of its parts, a thickness lower than or equal to 30 mm and being intended for an application where mechanical strength and/or abrasion resistance are of primary importance, said composition consisting essentially, in % by weight based on the oxides, of:

Thin ceramic articles obtained by fusing and casting in a mold a

The invention relates to a granular propping for use in petroleum extraction which has a high mechanical resistance and a density of between 3150 and 3250 kg/m.sup.3, the propping agent consisting of balls formed by melting, granulating and solidifying an initial composition comprising by weight, on the basis of the oxides, 47.1 to 48.7 parts of ZrO.sub.2, 52.9 to 51.3 parts of SiO.sub.2, the total of ZrO.sub.2 +SiO.sub.2 amounting to 100 parts, 8.2 to 16.9 parts of Al.sub.2 O.sub.3 and 4.1 to 8.5 parts of at least one oxide selected from the group formed by MgO, CaO, FeO and TiO.sub.2.

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Morieres, France

Daniel Urffer