Abstract:
A process and powder mixture are provided for the ceramic welding repair of electrocast refractory oxide materials, such as those used in parts of glassmaking and metallurgical furnaces exposed to severe high temperature conditions. The powder mixture, which is to be projected in an oxygen gas stream against a refractory surface to be repaired, comprises combustible particles such as aluminium and silicon and refractory oxide particles plus at least one constituent, for example sodium carbonate and/or excess silica, which produces a vitreous phase in the repair mass, thereby enhancing the bond between the repaired refractory material and the repair mass.
Abstract:
Electrical heating elements operable at high temperatures for long periods are produced by a method involving micropyretic synthesis. Compositions subjected to micropyretic synthesis comprises a powdery mass of electrically conductive and semiconductive material, a reactive system including a sub-micron particle size reactant capable of undergoing micropyretic synthesis, a grain growth inhibitor and a plasticizer or extrusion agent.
Abstract:
A method to at least partially impregnate a porous ceramic body with a metal comprising positioning a sacrificial porous ceramic transport means in physical contact with the metal and between the porous ceramic body to be impregnated and the metal; interposing a sufficient amount of a ceramic powder in contacting relationship between the ceramic body and the transport means to enable the metal to flow from the ceramic transport means to the ceramic body and insufficient to permit metal bonding between the transport means and the ceramic body, at least one constituent of the powder being wettable by, and chemically reactive with the metal; and maintaining at least the ceramic body and metal transport means at a temperature, and for a time, sufficient for at least a portion of the metal to flow through the transport means and into the ceramic body to impregnate the ceramic body a predetermined amount to form a metal impregnated ceramic body of near net shape.
Abstract:
The method provides for grinding of at least one component chosen from a group, which comprises iron, iron oxide, an oxide of an element of group I-VIII of the periodic system and its compound generating said oxide under heating, introduction of at least one metal of group I-VIII of the periodic system into the powder-like material obtained, after which the mixture obtained is subjected to thermal treatment in combustion conditions in an atmosphere of oxygen or air.
Abstract:
A ceramic sinter is produced by utilizing the heat of reaction of the thermit process as the heat source, wherein a preheating step precedes a sintering step, or a mixture of: (A) at least one ceramic powder, (B) at least one nonmetallic powder selected from the group consisting of carbon, boron and silicon powders, and (C) a metal powder and/or a nonmetallic powder other than the above-mentioned powder (B), is used as the raw material. This method gives homogeneous dense ceramic sinter and composite ceramic sinter. Furthermore the fine textures of the sinter and the composition and distribution of the composite ceramic phase can appropriately be controlled thereby.
Abstract:
The method provides for thermal treatment of an exothermic mixture in a burning regime and subjecting the resulting solid products to the influence of external forces directed tangentially and/or perpendicularly to their surface at a temperature from around or below their burning point up to 0.5 of their melting point with subsequent extraction of the obtained powdered refractory material. The reactor comprises a casing (1) with a reaction cavity (8) inside which are mounted a device (11) for feeding into it on exothermic mixture under pressure and a rotor (9) with a tip (10), both being connected to the cavity (8). The external surface of the tip (10) forms, together with the internal surface of the casing (1), an annular gap (12) for removing the powder refractory material.
Abstract:
A dense essentially non-porous composite ceramic material of a diboride of a group IVa metal, preferably titanium, and alumina in a 3 : 5 mole ratio has a macroscopically uniform structure made up of non-uniformly dispersed agglomerates of alumina of random shapes and dimensions and a fibrous sponge-like electrically conductive structure of submicronic grains of the group IVa metal boride in intimate wetting contact with the alumina agglomerates. The material is made by reaction hot pressing of coarse grain precursor powders.
Abstract:
A method of additive manufacturing to form a component comprises successively depositing a plurality of layers to form the component. Depositing at least one of the plurality of layers includes depositing a layer of a first particulate precursor over a platen, depositing a second particulate precursor on portions of the platen over the layer of the first particulate precursor specified by a controller, and directing energy to the second particulate precursor deposited on the portion of the platen to cause an exothermic chemical reaction between the first particulate precursor and the second particulate precursor. The exothermic chemical reaction produces heat that sinters products of the chemical reaction to fabricate the layer of the component.
Abstract:
Composition pulvérulente à base de silice poreuse pour soudure céramique, en particulier par projection, comprenant de 10 à 90 % d'une phase de particules siliceuses poreuse comprenant au moins 80 % en poids de cristobalite et au plus 15% en poids de tridymite et de phase amorphe résiduelle, par rapport au poids total de la composition, et de 90 à 10 % en poids d'additifs conventionnels formant une phase liante, par rapport au poids total de la dite composition, lesdites particules siliceuses poreuses présentant un d 50 compris entre 200 et 1000 μm, de préférence entre 350 et 800μm.
Abstract:
Herein described is a process for the preparation of dense ZrB2-SiC-ZrC based Ultra-High-Temperature Composite (UHTC) products, comprising the application of the self-propagating high temperature synthesis technique and/or of the electric current activated sintering technique on mixtures of Zirconium, Silicon, Boron carbide and optionally graphite, in powder form.