Abstract: There is described a process for the continuous production of alpha-calcium sulphate hemihydrate, the process comprising the steps of: mixing particulate gypsum, a habit modifier and water to form a gypsum slurry. The process further comprises calcining the gypsum slurry to provide an alpha-calcium sulphate hemihydrate slurry and filtering the alpha-calcium sulphate hemihydrate slurry to separate at least one fluid stream from the slurry, measuring a first control parameter of the at least one fluid stream or the alpha-calcium sulphate hemihydrate slurry; and combining the at least one fluid stream with further gypsum, further water and further habit modifier to form a further gypsum slurry wherein the process further comprises varying the amount of further habit modifier depending on a measured value of the first control parameter. An apparatus for performing the described process is also provided.

Abstract: An insulated tuckstone that includes a basic tuckstone and an insulating layer exhibiting a thermal conductivity lower than 2.0 W·m 1·K?1 between 20° C. and 500° C., exhibiting enough rigidity to be self-supporting and covering an insulated surface of the basic tuckstone. The insulated surface is included in the lower surface of the basic tuckstone, extending into the lower transition surface and representing more than 20% of the lower transition surface. The insulating layer has a chemical composition, as a percentage by mass on the basis of the oxides, such that Al2O3+SiO2+ZrO2+CaO+Na2O+MgO+K2O+TiO2+Fe2O3+HfO2+P2O5+Y2O3>80%.

Abstract: A prepreg including a support with, for more than 90% of the weight thereof, of ceramic fibers, and a thermoreversible liquefiable gel covering, at least in part, at least one portion of the ceramic fibers. The liquefiable gel including: 20% to 60% of ceramic particles and 0% to 10% of metal particles, both as percentage by volume based on the volume of the liquefiable gel; 0.2% to 10% of a thermoreversible hydrocolloid and 0% to 7% of one or more other constituents, both as a percentage by weight on the basis of the total weight of the ceramic particles and metal particles; the balance to 100% being water. It being possible for the ceramic particles and the metal particles to be replaced, partially or completely, by precursors of ceramic particles and of metal particles, respectively, capable of forming, by heat treatment above 200° C., ceramic particles and metal particles, respectively.

Abstract: Sintered product having a relative density of greater than 90%, with, to more than 80% of the volume thereof, a stack of flat ceramic platelets, the assembly of the platelets having a mean thickness of less than 3 ?m, having a width of greater than 50 mm, and including more than 20% of alumina, as a percentage on the basis of the weight of the product. The width of the product is the largest dimension measured in the plane in which the length of the product is measured, along a direction perpendicular to the direction of the length. The length of the product is the largest dimension thereof in a plane parallel to the general plane in which the platelets extend.

Abstract: A sintered material exhibiting the following chemical composition, as percentages by weight: iron oxide(s), expressed in the Fe2O3 form, ?85%, CaO: 0.1%-6%, SiO2: 0.1%-6%, 0.05% ?TiO2, 0?Al2O3, TiO2+Al2O3?3%, and constituents other than iron oxides, CaO, SiO2, TiO2 and Al2O3: ?5%. The CaO/SiO2 ratio by weight is between 0.2 and 7. The TiO2/CaO ratio by weight is between 0.2 and 1.5.

Abstract: Sintered product having a chemical analysis such that, in mass percentages: SiO2 content is greater than 0.2% and less than 2%, and CaO content is greater than 0.1% and less than 1.5%, and MgO content is less than 0.3%, and alumina and other elements being the complement at 100%, the content of other elements being less than 1.5%, having a relative density greater than 90%, comprising, for more than 90% of its volume, a stack of ceramic platelets (10) laid flat, all of said platelets having an average thickness less than 3 ?m, more than 95% by number of said platelets each containing more than 95% by mass of alumina, having a width (l) greater than 81 mm.

Abstract: An insulated tuckstone that includes a basic tuckstone and an insulating layer exhibiting a thermal conductivity lower than 2.0 Wm 1.K?1 between 20° C. and 500° C., exhibiting enough rigidity to be self-supporting and covering an insulated surface of the basic tuckstone. The insulated surface is included in the lower surface of the basic tuckstone, extending into the lower transition surface and representing more than 20% of the lower transition surface. The insulating layer has a chemical composition, as a percentage by mass on the basis of the oxides, such that Al2O3+SiO2+ZrO2+CaO+Na2O+MgO+K2O+TiO2+Fe2O3+HfO2+P2O5+Y2O3>80%.

Abstract: Sintered product having a relative density of greater than 90%, with, to more than 80% of the volume thereof, a stack of flat ceramic platelets, the assembly of the platelets having a mean thickness of less than 3 ?m, having a width of greater than 50 mm, and including more than 20% of alumina, as a percentage on the basis of the weight of the product. The width of the product is the largest dimension measured in the plane in which the length of the product is measured, along a direction perpendicular to the direction of the length. The length of the product is the largest dimension thereof in a plane parallel to the general plane in which the platelets extend.

Abstract: A sintered material exhibiting the following chemical composition, as percentages by weight: iron oxide(s), expressed in the Fe2O3 form, ?85%, CaO: 0.1%-6%, SiO2: 0.1%-6%, 0.05% ?TiO2, 0?Al2O3, TiO2+Al2O3?3%, and constituents other than iron oxides, CaO, SiO2, TiO2 and Al2O3: ?5%. The CaO/SiO2 ratio by weight is between 0.2 and 7. The TiO2/CaO ratio by weight is between 0.2 and 1.5.

Abstract: A sintered refractory product having the form of a block and consisting of a granulate formed by all the grains having a size larger than 100 ?m, referred to as “coarse grains”, and a matrix binding the coarse grains and consisting of the grains having a size smaller than or equal to 100 ?m, the granulate representing between 45% and 90% by mass of the product, the product having a composition such that, in a mass percentage based on the oxides: Al2O3>80%, SiO2<15%, Na2O<0.15%, Fe2O3<0.05%, CaO<0.1%, the other oxides forming the remainder up to 100%, and the Na2O content in the matrix being greater than 0.010%, in a mass percentage based on the mass of the product.

Abstract: Sintered product having a chemical analysis such that, in mass percentages: SiO2 content is greater than 0.2% and less than 2%, and CaO content is greater than 0.1% and less than 1.5%, and MgO content is less than 0.3%, and alumina and other elements being the complement at 100%, the content of other elements being less than 1.5%, having a relative density greater than 90%, comprising, for more than 90% of its volume, a stack of ceramic platelets (10) laid flat, all of said platelets having an average thickness less than 3 ?m, more than 95% by number of said platelets each containing more than 95% by mass of alumina, having a width (l) greater than 81 mm.

Abstract: A powder is disclosed having a coarse fraction representing more than 60% and less than 85% of the powder, as a weight percentage on the basis of the oxides, and that is constituted of particles having a size greater than or equal to 50 ?m, referred to as “coarse particles”, the powder comprising at least 5% of coated grains having a size greater than or equal to 50 ?m, as a weight percentage on the basis of the oxides of the powder, and a fine fraction, forming the balance to 100% as a weight percentage on the basis of the oxides, constituted of particles having a size of less than 50 ?m, referred to as “matrix particles”. The powder can be applied in combustion chambers in which the temperature may reach 1400° C.

Abstract: A sintered refractory product having the form of a block and consisting—of a granulate formed by all the grains having a size larger than 100 ?m, referred to as “coarse grains”, and—a matrix binding said coarse grains and consisting of the grains having a size smaller than or equal to 100 ?m, the granulate representing between 45% and 90% by mass of the product, said product having a composition such that, in a mass percentage based on the oxides: —Al2O3>80%, —SiO2<15%, —Na2O<0.15% —Fe2O3<0.05%, —CaO<0.1%,—the other oxides forming the remainder up to 100%, the Na2O content in the matrix being greater than 0.010%, in a mass percentage based on the mass of the product.

Abstract: A powder is disclosed having a coarse fraction representing more than 60% and less than 85% of the powder, as a weight percentage on the basis of the oxides, and that is constituted of particles having a size greater than or equal to 50 ?m, referred to as “coarse particles”, the powder comprising at least 5% of coated grains having a size greater than or equal to 50 ?m, as a weight percentage on the basis of the oxides of the powder, and a fine fraction, forming the balance to 100% as a weight percentage on the basis of the oxides, constituted of particles having a size of less than 50 ?m, referred to as “matrix particles”. The powder can be applied in combustion chambers in which the temperature may reach 1400° C.

Abstract: A device having a first part shrink-fitted with a first shrink ring, the first shrink ring being shrink-fitted with a second shrink ring exhibiting a lower thermal expansion coefficient than a thermal expansion coefficient of the first shrink ring.

Abstract: A device including a first part made of ceramic material shrink fitted with a first shrink ring, in which an edge of an axial end of a cylindrical portion of the first part to which the first shrink ring is fitted and an edge of an axial end of the first shrink ring belong to one and the same transverse plane.

Abstract: A device including a first part having a substrate made of a material based on a silicon compound, a coating made of a coating material having a ceramic oxide, a transition layer having silica extending between the substrate and the coating, the transition layer exhibiting a thickness of less than 10 ?m, and a first shrink ring and/or a layer made of a compliant material having an alloy with at least two materials selected from silver, gold and palladium, the coating defining at least a portion of the interface between the first part, and the first shrink ring and/or the layer made of a compliant material.

Abstract: Sintered refractory product including, in percentages by weight on the basis of the oxides, —more than 10% of chromium oxide Cr2O3, —more than 2% of hafnium oxide HfO2, —more than 1% of zirconium oxide ZrO2, the total content of chromium, hafnium and zirconium oxides Cr2O3+HfO2+ZrO2 being greater than 70%.

Abstract: A device including a first member joined to a second member, the joining being carried out via a compliant material having an alloy with at least two materials selected from silver, gold, and palladium, the second member being a shrink ring of the first member.

Abstract: A method of manufacturing a porous ceramic part, comprising the following steps in succession: a) preparing a mixture M containing a ceramic powder in suspension, at least one gelling agent and at least one foaming agent, at a mixing temperature which is higher than the gelling temperature of the gelling agent; b) shearing the mixture M at a foaming temperature which is higher than the gelling temperature, to obtain a foam; c) gelling the foam by cooling the mixture M to a temperature below the gelling temperature of the gelling agent; and d) drying the gelled foam to obtain a perform. According to the invention, a stabilizing agent is added to the mixture M, which agent has an instantaneous viscosity, in Pa·s, that increases by a factor of at least ten when a shear rate of the stabilizing agent is reduced from 100 s?1 to 0.