Abstract: Ceramic compositions based on yttrium oxide contain a minor amount of a titanium oxide and are readily sintered into dense ceramic shaped articles well adopted for metallurgical applications.

Abstract: The present invention relates to a ceramic based on yttrium oxide and titanium oxide. This ceramic has a light transmission percentage of at least 20% in a wavelength range between 0.5 and 8 .mu.m.It also relates to a sintering process for obtaining said ceramic.

Abstract: Shaped, porous filter members having a size and shape adapted for the filtration of liquid metals, e.g., the configuration of a honeycomb, are comprised of a porous alveolar ceramic material including from 10 to 20% SiO.sub.2, from 50 to 60% Al.sub.2 O.sub.3 and from 20 to 40% ZrO.sub.2, each percentage being by weight with respect to the total weight of said oxides, said Al.sub.2 O.sub.3 and SiO.sub.2 being present in the form of mullite, 3Al.sub.2 O.sub.3 /2SiO.sub.2, and the combined weight of the zirconia and mullite comprising at least 90% by weight of said alveolar ceramic material.

Abstract: Method of welding two hollow ceramic half-components containing an organic binder whereby each half-component is first loaded into a die, the jointing planes of the two half-components are then brought into contact by bringing together the two dies, working pressure is thereafter applied to one of the half-components in a direction perpendicular to the jointing planes and vibration is simultaneously applied to the other half-component in a direction parallel to the jointing planes to effect the welding of the two half-components by interpenetration. The two dies are then separated and the joined monobloc component is removed and sintered without altering the component's monolithic quality.

Abstract: A method of manufacturing a composite structure of ceramic material which is reinforced by refractory fibers, wherein a slip (11) is prepared from a synthetic resin having good wetting properties on ceramic material and fibers, embedding fibers (15) in the slip, eliminating the liquid phase from the slip by drying (16), eliminating the synthetic resin from the formed structure by heating, and sintering the fiber-impregnated ceramic material, wherein a synthetic resin solvent is incorporated in the slip, and wherein the fibers are inserted in the slip in the form of an assembly which is a sheet or roving, before the drying.

Abstract: An improved method of manufacturing a composite structure of ceramic material reinforced by refractory fibers is disclosed, whereby the fibers are first embedded in a slip of the ceramic material containing a synthetic resin with good ceramic and fiber wetting properties and a solvent of said resin, the liquid phase is thereafter eliminated from the slip by drying, the synthetic resin is driven from the formed structure by heating, and the fiber-reinforced ceramic material is sintered. The improvement consists in avoiding the use of costly aluminum-nitride powder by initially incorporating an aluminum powder in the slip along with the resin solvent and nitriding the powder in the structure, after drying and firing, but before sintering.

Abstract: In a method of manufacturing parts or powders made of a compound of silicon or of a metal by exothermally reacting parts or powders of silicon or a metal in the solid state with a gas, wherein the differential flow rate or the pressure variation of the reactive gas in contact with the part or the powder is sensed, and the reaction is performed at increasing temperatures as a function of the said differential flow rate or pressure of the reactive gas:the improvement wherein a maximum differential flow rate or a maximum speed of pressure drop of the reactive gas is predetermined as a function of the chemical nature of the parts or powders, and optionally as a function of the density and the size of the parts, and the rise in temperature is suspended when the differential flow rate or the speed of pressure drop of the reactive gas reaches the predetermined maximum value, beyond which the reaction would run away and prevent complete transformation of the parts or the powders being obtained.

Abstract: The present invention relates to a ceramicized refractory composite and to a process for manufacturing same, wherein a multidirectional woven network is impregnated with a suspension of a ceramic powder and a fluid composition of a substance producing, under the action of heat treatment, a body of the same nature as the ceramic powder of said suspension.

Abstract: A method of manufacturing a sintered silicon carbide ceramic part in which is formed a mixture of carbide powder with a sintering additive based on boron, beryllium or aluminium, and an injection moulding additive comprising a mixture of polystyrene and a wax. A moulded part is manufactured by injection moulding and is then baked and is finally sintered.Polystyrene is used simultaneously as a moulding agent and as a carbonizable substance. When the moulded part is baked it is heated in air to a temperature between 230.degree. C. and 330.degree. C. and is then kept at that temperature for a fairly long time to remove the wax and to reticulate and oxidize the polystyrene.Application to manufacturing dense sintered parts.

Abstract: A silicon nitride material is obtained by natural sintering in the presence of a small quantity of yttrium oxide. The method comprises the steps of mixing silicon powder with relatively small quantities of aluminum powder and yttrium oxide powder, nitriding the mixture of powders, re-crushing the nitrided mixture of powders, shaping the re-crushed powders, and then sintering the shaped re-crushed powders.

Abstract: The invention relates to the manufacture of a body of a cellular structure by extruding a ceramic material through a die. The die comprises a succession of coaxial components (6, 10) fitted one round another, with two adjacent components defining between them longitudinal ducts (2) whose downstream ends communicate with an annular duct (3) and wherein the bottoms of said coaxial components fitted one round another have essentially radial notches (4) level with the annular ducts, the width of said notches being less than that of the longitudinal ducts, so that the ceramic material which flows through said longitudinal ducts is evenly distributed in the annular ducts and in the radial notches to form a body with a cellular structure directly on extrusion.The invention has application to thin-walled honeycomb ceramic structures.

Abstract: A ceramic unit for indirect heat exchange, said unit being formed by extruding raw ceramic material in a parallel duct configuration, piercing a first series of inlet and outlet orifices for a fluid at the ends of a first series of ducts, the axes of said orifices being perpendicular to those of the ducts, and firing the unit. The inlet orifices (5) and/or the outlet orifices (9) are formed by making oblique cuts (7,10) on the ends of the rows of ducts to provide inlet or outlet openings perpendicular to the common direction of the ducts and then closing off the ends of the obliquely cut rows. Application to heat exchangers for turbine engines.

Abstract: The invention relates to a process and apparatus for applying a covering on heat-sensitive articles by means of a blowpipe. The covering is applied by a sequence of very short spraying or blasting steps separated from one another by comparatively long cooling stages. The article is carried by a continuous moving support member in the form of a circular wheel, the articles being rotatably mounted in lateral rims on the wheel.