Abstract: A process for manufacturing SiC wherein the emissions of polluting gases are minimized, by reduction of silicon oxide by an excess of carbon, the process including electrically heating a resistor at the heart of a mixture of raw materials consisting of a carbon-based source chosen from petroleum cokes and a source of silicon, especially a silica having a purity of greater than 95% of SiO2, in order to give rise, at a temperature above 1500° C., to the simplified reaction: SiO2+3C=SiC+2CO (1), wherein the carbon-based source first undergoes a treatment for removing the contained hydrogen, so that its elemental hydrogen content (EHWC) is less than 2% by weight.

Abstract: A process for producing fused alumina-zirconia grits includes mixing raw materials suitable to produce grits with the following chemical composition, in % by weight: ZrO2+HfO2: 10–60%, Al2O3: 38–90%, SiO2: <0.8%, and Impurities: <1.2%. The process also includes adding carbon and aluminum metal to the mixture of raw materials to obtain a charged batch containing, in % by weight,: Carbon: 0.4–1% Aluminum metal: 0.5–2.5%. The process further includes melting the charged batch in an electric arc furnace with a voltage of 175–205 V and a delivered specific electrical energy of 2.5 to 4 kWh per kg of charge.

Abstract: The use of blocks (1, 2, 3, 4) based on sintered tin oxide for producing the throat of a glass furnace.

Abstract: Oxidized alumina-zirconia-silica (AZS) refractories containing 40 wt % to 55 wt % Al2O3, 32 wt % to 45 wt % ZrO2, 10 wt % to less than 16 wt % SiO2 and 1 wt % to 3 wt % of an alkali metal oxide selected from Na2O, K2O and mixtures thereof have a microstructure essentially comprising alpha-alumina crystals, free zirconia crystals, eutectic crystals and an intercrystalline vitreous phase. At least in an active area, more than 20% by number of the free zirconia crystals have a dendritic shape and are interleaved with each other and with eutectic crystals and at least 40% by number of the dendritic free zirconia crystals have a dimension greater than 300 &mgr;m.

Abstract: Fused cast AZS products that contain: Al2O3: 45-65 wt. %, ZrO2: 10.0-29.0 wt. %, SiO2: 20.0-24.0 wt. %, SiO2/(Na2O+K2O) weight ratio: 4.5-8, and other species: 0.5-4.0 wt. % These products may be produced from manufacturing waste or recycled spent materials.

Abstract: Fused and cast AZS products, characterized in that they contain:

Abstract: Oxidized alumina-zirconia-silica (AZS) refractories containing 40 wt % to 55 wt % Al2O3, 32 wt % to 45 wt % ZrO2, 10 wt % to less than 16 wt % SiO2 and 1 wt % to 3 wt % of an alkali metal oxide selected from Na2O, K2O and mixtures thereof have a microstructure essentially comprising alpha-alumina crystals, free zirconia crystals, eutectic crystals and an intercrystalline vitreous phase. At least in an active area, more than 20% by number of the free zirconia crystals have a dendritic shape and are interleaved with each other and with eutectic crystals and at least 40% by number of the dendritic free zirconia crystals have a dimension greater than 300 &mgr;m.

Abstract: The invention relates to a novel sintered material, characterized in that it is produced from a batch containing 5 to 40% zircon and in that it has the following chemical composition in % by weight:______________________________________ ZrO.sub.2 + HfO.sub.2 82-96 SiO.sub.2 1.7-14 TiO.sub.2 0.2-3 Y.sub.2 O.sub.3 0.4-5 Al.sub.2 O.sub.3 0.2-2.

Abstract: The invention covers a fused cast refractory material essentially consisting of .beta. alumina and having the following chemical analysis expressed as molar percentages:11.25% to 15.45% of at least one alkaline metal oxide selected from the group comprising Na.sub.2 O, Li.sub.2 O and K.sub.2 O provided that Na.sub.2 O represents at least 9.3%,0 to 2.97% SiO.sub.2,81.38% to 88.75% Al.sub.2 O.sub.3, andat most 0.2% impuritiesand in which .beta. alumina represents at least 98% of the crystallized phases.

Abstract: A modular ceramic protective part for a metal blowing grate (1) in a catalytic cracker regenerator, comprises a tubular nozzle portion (4) and a flange portion (6) extending substantially perpendicularly from one end thereof. The part is useful in chemical engineering.

Abstract: 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:a) no organic or inorganic binder binds the fibers to one another;b) the fibers have the following chemical composition, as % by weight:Al.sub.2 O.sub.3 : 33-45%SiO.sub.2 : 41-53%ZrO.sub.2 : 5.5-17%MgO: 0.02-2%other oxides:<0.50% with Fe.sub.2 O.sub.3 +TiO.sub.2 .ltoreq.0.20% and Na.sub.2 O+CaO+K.sub.2 O.ltoreq.0.30%;c) the said fibers homogeneously have, throughout the entire body of the component, a degree of crystallinity of not less than 30% and not more than 64%, the crystals present being essentially formed of mullite crystals and of quadratic zirconia; andd) the said component has a linear shrinkage of no more than 3% after being held for 24 hours at 1450.degree. C.

Abstract: 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.

Abstract: The invention relates especially to a mixture of grains and particles of fused vitreous silica produced by dry mixing: (i) a moderately coarse particle size fraction of fused vitreous silica, (ii) a fine particle size fraction of fused vitreous silica, in which at least 95% by weight of the grains are smaller than 40 .mu.m, (iii) substantially spherical particles of fume silica, and (iv) optionally, at least one particle size fraction of fused vitreous silica which is coarser than fraction (i), the constituents (i) to (iv) being employed in the following proportions by weight: (i) 15-70%, (ii) 15-55%, (iii) 3-15% and (iv) 0-52%. The mixture can be used for the production of articles made of sintered vitreous silica.

Abstract: 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.

Abstract: A feeder trough for transferring molten glass from a glass furnace to an object-forming station, the feeder trough comprising a channel at one of its ends to the furnace and at its other end to a bowl having at least one feeder orifice a sill which has, on its downstream face, a substantially vertical wall, occupies the entire width of the channel and has a thickness of approximately 4 to 10 cm and a height such that it allows a stream of glass approximately 8 to 10 cm thick to pass over it; and a heatable bottom drain provided upstream of the sill and practically adjoining the latter.

Abstract: The invention relates to the regenerators of glass melting furnaces. It relates more particularly to a ceramic element for equipping regenerators of glass melting furnaces, having at least one vertical wall, the mean thickness of which is at the most 40 mm, characterized by the presence, on at least one face of this vertical wall, of a plurality of obstacles forming an integral part of the element, the protrusion of the obstacles relative to the base surface of the wall being at least 5 mm, the ratio of the distance separating two consecutive obstacles in the vertical direction to the said protrusion being comprised between 3 and 15, and the angle x formed by the obstacle with the base surface of the wall in the given direction of movement of the fumes and the angle y formed by the obstacle with the base surface of the wall in the given direction of movement of the air to be heated being such that x is less than or equal to y. Application in the glass industry.

Abstract: 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.

Abstract: 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:______________________________________ Al.sub.2 O.sub.3 40-75 ZrO.sub.2 20-55 SiO.sub.2 5-20 Na.sub.2 O 0-2.7 K.sub.2 O 0.15-4.25 Fe.sub.2 O.sub.3 + TiO.sub.2 + CaO + MgO 0-2, ______________________________________with the condition that the weight ratio ##EQU1## is between 0.07 and 0.14 inclusive.

Abstract: A process for making a monolithic heat-exchanger body includes the steps of arranging a plurality of rigid plastic tubular members in a mold, casting a composition comprising a refractory material and water into the mold and around the tubular member to form molded body, drying the molded body, and passing a hot gas through the tubular members in the molded body to remove them.

Abstract: A heat exchanger for use in industries concerned with utilizing corrosive or abrasive fluids, either at low or high temperatures, is made of a monolithic body molded from refractory material and includes at least one channel for the fluid to be heated and at least one channel for the fluid to be cooled, these channels being integrally molded and in a mutual heat-exchange relationship.