The invention concerns an exchangeable nozzle for a nozzle changer system for billet casting, a method for manufacturing such a nozzle, a nozzle changer system comprising such a nozzle and a tundish comprising such a nozzle changer system.

The invention concerns an exchangeable nozzle for a nozzle changer system for billet casting, a method for manufacturing such a nozzle, a nozzle changer system comprising such a nozzle and a tundish comprising such a nozzle changer system.

Provided is a refractory product which is not impregnated with pitch or the like, wherein it has higher corrosion-erosion resistance and thermal shock resistance as compared to a refractory product subjected to pitch or the like-impregnation treatment. The refractory product which is not impregnated with tar or pitch is characterized in that, in terms of values of physical properties of a sample of the refractory product as measured after heat-treating the sample in a non-oxidizing atmosphere at 1200° C.: an apparent porosity is 7% or less; a total void volume of pores having a pore diameter of 1 μm or less is 80% or more of an integrated void volume of pores of the entire sample of the refractory product; and a gas permeability is 50×10.sup.−17 m.sup.2 or less.

Provided is a refractory product which is not impregnated with pitch or the like, wherein it has higher corrosion-erosion resistance and thermal shock resistance as compared to a refractory product subjected to pitch or the like-impregnation treatment. The refractory product which is not impregnated with tar or pitch is characterized in that, in terms of values of physical properties of a sample of the refractory product as measured after heat-treating the sample in a non-oxidizing atmosphere at 1200° C.: an apparent porosity is 7% or less; a total void volume of pores having a pore diameter of 1 μm or less is 80% or more of an integrated void volume of pores of the entire sample of the refractory product; and a gas permeability is 50×10.sup.−17 m.sup.2 or less.

Provided is a ZrO.sub.2—CaO—C based refractory material which is capable of maintaining high adhesion resistance over a long period of time, while exhibiting significant slaking resistance, and suppressing self-fluxing, i.e., exhibiting corrosion-erosion resistance. The refractory material comprises a CaO—ZrO.sub.2 composition containing a CaO component in an amount of 40% by mass to 60% by mass, wherein a mass ratio of the CaO component to a ZrO.sub.2 component is 0.67 to 1.5, and wherein the CaO—ZrO.sub.2 composition includes a eutectic microstructure of CaO crystals and CaZrO.sub.3 crystals, wherein a width of each of the CaO crystals observable in a cross-sectional microstructure is 50 μm or less.

An isostatically pressed product (10, 11, 12, 13, 14) for use in handling of molten metals comprising: a body (20) made from a first refractory composition (50); the body (20) comprises a surface (21); and at least one liner section (30.1) applied partially onto the surface (21) of the body (20); the at least one liner section (30.1) is made from a second refractory composition (51); the at least one liner section (30.1, 30.2) forming the liner (30) of the body (20); whereas in at least one cross-section of the product, the surface (21) of the body (20) in a region covered with the liner (30), comprises at least one convex (41) and at least two concave (42) sections and a method for manufacturing an isostatically pressed product (10, 11, 12, 13, 14) for use in handling of molten metals.

A refractory material contains: 40 mass % or more of MgO; 4 to 30 mass % of a free carbon component; and one or more of B.sub.2O.sub.3, P.sub.2O.sub.5, SiO.sub.2 and TiO.sub.2, 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 B.sub.2O.sub.3, P.sub.2O.sub.5, SiO.sub.2 and TiO.sub.2 exists entirety or partially in a surface of each of the MgO-containing particles.

A refractory material contains: 40 mass % or more of MgO; 4 to 30 mass % of a free carbon component; and one or more of B.sub.2O.sub.3, P.sub.2O.sub.5, SiO.sub.2 and TiO.sub.2, 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 B.sub.2O.sub.3, P.sub.2O.sub.5, SiO.sub.2 and TiO.sub.2 exists entirety or partially in a surface of each of the MgO-containing particles.

A collector nozzle for continuous casting may include: a nozzle body extended toward a shroud nozzle, and having an internal movement path through which molten steel is moved; a first case covering a side surface of the nozzle body; and a second case including a second metal component, connected to the first case, and covering an exit surface of the nozzle body facing the shroud nozzle. The first case can include a first metal component, and the first and second cases may be connected through welding or formed as one body.

A collector nozzle for continuous casting may include: a nozzle body extended toward a shroud nozzle, and having an internal movement path through which molten steel is moved; a first case covering a side surface of the nozzle body; and a second case including a second metal component, connected to the first case, and covering an exit surface of the nozzle body facing the shroud nozzle. The first case can include a first metal component, and the first and second cases may be connected through welding or formed as one body.