Krosakiharima Corporation

Nippon Steel Sumitomo Metal Corporation

Akinari Sasaki

Katsumi Morikawa

Ling Li

Shinichi Fukunaga

Joki Yoshitomi

Hiroshi Otsuka

Yoshitaka Hiraiwa

Kazuhisa Tanaka

Takashi Sadano

Taro Makino

Naomi Yoshitsugu

Koichi Haren

Yuichi Tsukaguchi

Keiichiro Neba

Li Ling

A refractory material contains: 40 mass % or more of MgO; 4 to 30 mass % of a free carbon component; and one or more of BO, PO, SiOand TiO, in a total amount of 0.3 to 3 mass %, with the remainder being at least one other type of additional refractory component. A void layer exists in an interface between a carbon-containing matrix microstructure residing at least on opposite sides of a maximum-size one of a plurality of MgO-containing particles in the refractory material, and the maximum-size MgO-containing particle. A sum of respective thicknesses of the void layer at two positions on the opposite sides is 0.2 to 3.0% of a ratio with respect to particle size of the maximum-size MgO-containing particle. An inorganic compound of MgO and the one or more of BO, PO, SiOand TiOexists entirety or partially in a surface of each of the MgO-containing particles.

Refractory material and casting nozzle

A refractory product includes CaO component-containing refractory particles and MgO component-containing refractory particles. The refractory material contains, a chemical composition measured after it has undergone heating in a non-oxidizing atmosphere at 1000&#xb0; C., one or more of the following metal oxides BO, TiO, VO, POand SiOin a total amount of 0.1 to 5.0 mass %, and free carbon in an amount of 2 to 35 mass %, with the remainder including CaO and MgO whose mass ratio (CaO/MgO) is in the range of 0.1 to 1.5. In microscopic observation performed at room temperature on the refractory material which has undergone the above heating, an inorganic film comprised of CaO and the one or more metal oxides is formed in at least each CaO surface of the refractory particles each containing either one or both of a CaO component and an MgO component, with a thickness of 0.1 to 25 &#x3bc;m.

In an operation of continuous casting of steel grade such as aluminum-killed steel where a nozzle clogging phenomenon is particularly likely to occur, it is intended to prevent adhesion of inclusions (typically, AlO) on a nozzle used in the casting operation, and clogging of the nozzle due to the inclusions. A refractory materialis arranged to define a part or an entirety of a molten steel-contacting surface of a continuous casting nozzle, wherein the refractory materialcontains: a CaO component in an amount of 0.5 mass % or more; one or both of BOand RO (R is one selected from the group consisting of Na, K and Li) in an amount of 0.5 mass % or more; AlOin an amount of 50 mass % or more; and free carbon in an amount of 8.0 to 34.5 mass %, and wherein a total amount of CaO, BOand RO is in the range of 1.0 to 15.0 mass %, and a mass ratio of CaO/(BO+RO) is in the range of 0.1 to 3.0.

Refractory material, continuous casting nozzle using the refractory material, production methods for the continuous casting nozzle, and continuous casting methods using the continuous casting nozzle

In a insert-type continuous casting nozzle comprising a highly functional layer formed to have a high corrosion resistance, a high anti-attachment capability, etc., and provided to define an inner bore thereof, the present invention is directed to providing a refractory material (mortar) for an intermediate layer of the continuous casting nozzle, which has a property capable of fixing an inner bore-side layer to an outer periphery-side layer (a nozzle body) of the continuous casting nozzle, while preventing the occurrence of expansion splitting in the outer periphery-side layer due to a difference in thermal expansion between the inner bore-side and outer periphery-side layers, and a continuous casting nozzle using the refractory material for the intermediate layer. The refractory material for the intermediate layer contains a hollow refractory aggregate in an amount of 10 to 75 volume %, wherein a ratio of an average radius R of each particle of the aggregate to an average wall thickness t of the particle satisfies the following relation: R/t&#x2267;10. This refractory material is disposed between an inner bore-side layer () and an outer periphery-side layer () of a continuous casting nozzle.

Refractory material for nozzle for use in continuous casting, and continuous casting nozzle

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Fukuoka, Japan

Akinari Sasaki