Abstract: It is an object to provide an aluminum oxycarbide composition capable of suppressing oxidation of Al4O4C during use to maintain advantageous effects of Al4O4C for a long time. In an aluminum oxycarbide composition comprising Al4O4C crystals, the Al4O4C crystals have an average diameter of 20 ?m or more, based on an assumption that a cross-sectional area of each Al4O4C crystal during observation of the aluminum oxycarbide composition in an arbitrary cross-section thereof is converted into a diameter of a circle having the same area as the cross-sectional area. This aluminum oxycarbide composition can be produced by subjecting a carbon-based raw material and an alumina-based raw material to melting in an arc furnace and then cooling within the arc furnace.

Abstract: Disclosed is a method of producing a plate brick, which comprises: adding an organic binder to a refractory raw material mixture containing aluminum and/or an aluminum alloy; kneading them; forming the kneaded mixture into a shaped body; and burning the shaped body in a nitrogen gas atmosphere at a temperature of 1000 to 1400° C., wherein: when a temperature of a furnace atmosphere is 300° C. or more, the atmosphere is set to a nitrogen gas atmosphere; and when the temperature of the furnace atmosphere is 1000° C. or more, an oxygen gas concentration in the atmosphere is maintained at 100 volume ppm or less, and a sum of a carbon monoxide gas concentration and a carbon dioxide gas concentration is maintained at 1.0 volume % or less.

Abstract: Provided is an aluminum oxycarbide composition production method capable of increasing a yield of Al4O4C while reducing a content rate of Al4C3 and achieving high productivity, and an aluminum oxycarbide composition. The method comprises: preparing a blend substantially consisting of a carbon-raw material having a mean particle diameter of 0.5 mm or less and an alumina-raw material having a mean particle diameter of 350 ?m or less, wherein a mole ratio of the carbon-raw material to the alumina-raw material (C/Al2O3) is in a range of 0.8 to 2.0; homogeneously mixing the blend to allow a variation in C component to fall within ±10%; and melting the obtained mixture in an arc furnace at 1850° C. or more.

Abstract: In a carbon-containing refractory composed of a refractory aggregate, a carbon based raw material, and a carbon bond connecting between the refractory aggregate or the carbon based raw material, transition metal-containing nanoparticles having particle diameters of 1,000 nm or less and containing a transition metal are contained in the above-described carbon bond while being dispersed. When the carbon-containing refractory is heat-treated, flexible structures of carbon fiber-shaped textures having diameters of 50 nm or less are formed in the inside of a carbon bond and, thereby, an increase in strength, a reduction in modulus of elasticity, and a reduction in thermal expansion coefficient are facilitated. Therefore, a carbon-containing refractory exhibiting high thermal shock resistance, high abrasion resistance, and high corrosion resistance are provided.

Abstract: It is an object to provide an aluminum oxycarbide composition capable of suppressing oxidation of Al4O4C during use to maintain advantageous effects of Al4O4C for a long time. In an aluminum oxycarbide composition comprising Al4O4C crystals, the Al4O4C crystals have an average diameter of 20 ?m or more, based on an assumption that a cross-sectional area of each Al4O4C crystal during observation of the aluminum oxycarbide composition in an arbitrary cross-section thereof is converted into a diameter of a circle having the same area as the cross-sectional area. This aluminum oxycarbide composition can be produced by subjecting a carbon-based raw material and an alumina-based raw material to melting in an arc furnace and then cooling within the arc furnace.

Abstract: Provided is an aluminum oxycarbide composition production method capable of increasing a yield of Al4O4C while reducing a content rate of Al4C3 and achieving high productivity, and an aluminum oxycarbide composition. The method comprises: preparing a blend substantially consisting of a carbon-raw material having a mean particle diameter of 0.5 mm or less and an alumina-raw material having a mean particle diameter of 350 ?m or less, wherein a mole ratio of the carbon-raw material to the alumina-raw material (C/Al2O3) is in a range of 0.8 to 2.0; homogeneously mixing the blend to allow a variation in C component to fall within ±10%; and melting the obtained mixture in an arc furnace at 1850° C. or more.

Abstract: Disclosed is a magnesia-carbon based sleeve brick for steelmaking converters, which is obtained by adding, to a refractory raw material mix containing 60 to 95 mass % of a magnesia raw material and 5 to 20 mass % of graphite, a metal powder of one or more selected from the group consisting of Al, Si, Mg, Ca, Cr and an alloy thereof, in an amount of greater than 3 to 6 mass %, and an organic binder, in addition to 100 mass % of the refractory raw material mix, and subjecting the resulting mixture to kneading, forming and heat treatment, wherein the sleeve brick is used under a condition that a thickness thereof is set at 70 mm or less. This makes it possible to prevent cracking which would otherwise occur in the sleeve brick itself, to allow the sleeve brick to have enhanced durability. One or more selected from the group consisting of B, B4C, MgB2, CaB6, and CrB may be further added in an amount of 0.

Abstract: Disclosed is a method of producing a plate brick, which comprises: adding an organic binder to a refractory raw material mixture containing aluminum and/or an aluminum alloy; kneading them; forming the kneaded mixture into a shaped body; and burning the shaped body in a nitrogen gas atmosphere at a temperature of 1000 to 1400° C., wherein: when a temperature of a furnace atmosphere is 300° C. or more, the atmosphere is set to a nitrogen gas atmosphere; and when the temperature of the furnace atmosphere is 1000° C. or more, an oxygen gas concentration in the atmosphere is maintained at 100 volume ppm or less, and a sum of a carbon monoxide gas concentration and a carbon dioxide gas concentration is maintained at 1.0 volume % or less.

Abstract: Disclosed is a magnesia-carbon based sleeve brick for steelmaking converters, which is obtained by adding, to a refractory raw material mix containing 60 to 95 mass % of a magnesia raw material and 5 to 20 mass % of graphite, a metal powder of one or more selected from the group consisting of Al, Si, Mg, Ca, Cr and an alloy thereof, in an amount of greater than 3 to 6 mass %, and an organic binder, in addition to 100 mass % of the refractory raw material mix, and subjecting the resulting mixture to kneading, forming and heat treatment, wherein the sleeve brick is used under a condition that a thickness thereof is set at 70 mm or less. This makes it possible to prevent cracking which would otherwise occur in the sleeve brick itself, to allow the sleeve brick to have enhanced durability. One or more selected from the group consisting of B, B4C, MgB2, CaB6, and CrB may be further added in an amount of 0.

Abstract: Disclosed is a continuous casting nozzle, which comprises a layer formed to have high functions, such as high corrosion resistance and high anti-deposition capability, and disposed on the side of an inner bore thereof to serve as an inner bore-side layer, so as to enhance durability, wherein the continuous casting nozzle is capable of preventing expansion cracking of an outer periphery-side layer serving as a nozzle body thereof, due to a difference in thermal expansion between respective compositions of the inner bore-side layer and the outer periphery-side layer, while preventing peel-off of the inner bore-side layer during casting.

Abstract: A carbon-containing refractory is provided, which can improve the thermal shock resistance, the abrasion resistance, and the corrosion resistance without degrading the oxidation resistance. In a carbon-containing refractory composed of a refractory aggregate, a carbon based raw material, and a carbon bond connecting between the refractory aggregate or the carbon based raw material, transition metal-containing nanoparticles having particle diameters of 1,000 nm or less and containing a transition metal are contained in the above-described carbon bond while being dispersed. When the carbon-containing refractory is heat-treated, flexible structures of carbon fiber-shaped textures having diameters of 50 nm or less are formed in the inside of a carbon bond and, thereby, an increase in strength, a reduction in modulus of elasticity, and a reduction in thermal expansion coefficient are facilitated.

Abstract: A nozzle for continuous casting of clean steel is capable of preventing adhesion of Al2O3-based inclusions to a wall surface of the inner hole of the nozzle while fully achieving an effect of a swirl vane. The swirl vane prevents drift in molten steel passing through the inner hole. The swirl vane is disposed in the inner hole. A wall surface is at least partly formed as a tubular-shaped refractory layer and is prepared by controlling a weight ratio of CaO/MgO and an apparent porosity to have a thickness of 3 to 20 mm, so as to prevent adhesion of Al2O3-based inclusions to the wall surface and the swirl vane while effectively maintaining the anti-drift effect for long hours. Further, inert gas is injected into a molten steel flow between an upper nozzle and the swirl vane to facilitate surfacing of Al2O3-based inclusions in a mold and reduce Al2O3-based inclusions in molten steel so as to achieve stable casting operation and high-quality steel with high cleanness.

Abstract: Disclosed is a nozzle for continuous casting of clean steel, capable of preventing adhesion of Al2O3-based inclusions to a wall surface of the inner hole of the nozzle while fully achieving an effect of a swirl vane provided as a means to prevent occurrence of drift in molten steel passing through the inner hole. The swirl vane is disposed in the inner hole having the wall surface at least partly formed as a tubular-shaped refractory layer prepared by controlling a weight ratio of CaO/MgO and an apparent porosity to have a thickness of 3 to 20 mm, so as to prevent adhesion of Al2O3-based inclusions to the wall surface and the swirl vane while effectively maintaining the anti-drift effect for long hours. Further, inert gas is injected into a molten steel flow between an upper nozzle and the swirl vane to facilitate surfacing of Al2O3-based inclusions in a mold and reduce Al2O3-based inclusions in molten steel so as to achieve stable casting operation and high-quality steel with high cleanness.

Abstract: The present invention provides a technique of applying a CaO-containing material to a nozzle unit for casting of aluminum-killed steel, in such a manner that the amount of large-size alumina inclusions in slabs can be reduced irrespective of nozzle type, such as single-part type or multi-part type. The amount of large-size alumina inclusions in slabs obtained using a single-part type or multi-part type nozzle unit, which has an inner hole to be used for pouring molten steel from a tundish to a mold therethrough and CaO-containing refractories applied to a surface of the inner hole, has a strong correlation with the entire surface area of the inner hole of the nozzle unit and the amount of CaO contained in the employed refractories. According to the present invention, 50% or more of the entire surface area of the inner hole of the nozzle unit is formed of refractories containing 20 mass % or more of CaO to allow the amount of large-size alumina inclusions to be reduced.