Krosakiharima Corporation

Lwb Refractories Company

Koji Ogata

Donald Bruce Hoover

Shinichi Fukunaga

Saeko Koga

Disclosed is anti-alumina-buildup refractories for casting nozzles, which comprises a refractory aggregate including 20 mass % or more of CaO component, and 10 mass % or more of clinker particles each containing CaO as a mineral phase, on the basis of 100 mass % of the entire composition. At least a part of the surfaces of the CaO exposed from the surfaces of the corresponding clinker particles is formed with a CaCOfilm. The CaCOfilm releases COgas through thermal decomposition to smooth an operative surface of the nozzle so as to prevent the accretion of metal thereon, so that CaO is continuously supplied to alumina attached on the operative surface to prevent alumina buildup. In addition, the CaCOfilm effectively prevents the hydration of CaO due to a hydration reaction.

Anti-alumina-buildup refractories for casting nozzles

A method of producing an immersion nozzle for continuous casting, which includes integrally molding a first zirconia-graphite compound applied to a powder-line portion of the nozzle, and a second compound applied to at least an inner hole portion of the nozzle. The second compound includes 10 mass % or more of clinker particles each containing CaO as a mineral phase, and the surface of at least a part of the clinker particles is subjected to an anti-hydration treatment, such as a heat treatment to be performed under a COatmosphere to convert CaO to CaCO. The method can suppress volume expansion caused by the reaction between CaO and water released from resin added as binder, so as to prevent the occurrence of cracks during a burning process of the molded piece.

Method of producing anti-alumina-buildup immersion nozzle for continuous casting

Disclosed is a continuous casting nozzle having a refractory portion formed to contain a dolomite clinker and arranged to define a surface region adapted to be in contact with molten steel, which is capable of protecting a working surface of the nozzle from alumina build-up due to alumina in molten steel, while improving corrosion resistance, even during long-term continuous casting of molten steel. The refractory portion is prepared by adding a binder to a mixed material and subjecting the obtained mixture to kneading, forming and heat treatment. The mixed material comprises a dolomite clinker which has an average particle size of 0.8 mm or less and a CaO content of 50 mass % or less. The mixed material has a ratio W1/W2 of 0.33 or more, wherein W1 is a content by mass of CaO, and W2 is a content by mass of MgO. The mixed material comprises a dolomite clinker and a magnesia clinker. Alternatively, the mixed material comprises a dolomite clinker and a magnesia clinker. The mixed material has a ratio WD/WM in the range of 0.5 to 15, wherein WD is a mass % of dolomite clinker particles having a particle size of 1 mm or less in a particle size distribution of the dolomite clinker, and WM is a mass % of magnesia clinker particles having a particle size of 1 mm or less in a particle size distribution of the magnesia clinker. Further, the mixed material has a ratio W1/W2 in the range of 0.33 to 3.0, wherein W1 is a content by mass % of a CaO component in the dolomite clinker, and W2 is a content by mass % of an MgO component in the magnesia clinker.

Nozzle for use in continuous casting

A bonding structure between a nozzle body of a continuous casting nozzle and a refractory sleeve inserted into the nozzle body, wherein the refractory sleeve contains 20 mass % or more of CaO. An adhesive including a mixture of a refractory aggregate and a binder is applied to a joint zone defined in either one of at least a portion of the outer peripheral surface of the refractory sleeve and at least a portion of the inner surface of the hollowed nozzle to which the refractory sleeve is attached, or between the inner surface of the nozzle body and the outer peripheral surface of the refractory sleeve inserted into the nozzle body. The adhesive is adjusted to have a porosity in the range of 15 to 90% after dried in the joint zone. The bonding structure has a function of relaxing a thermal stress due to exponential expansion of the refractory sleeve caused by molten steel flowing into an inner hole of the nozzle during use, so as to prevent the detachment of the refractory sleeve and adverse affects on the nozzle body due to thermal expansion of the refractory sleeve.

Growing community of inventors

Kitakyushu, Japan

Koji Ogata