Conventional sintering processes convert a portion of cBN to hBN which is softer than cBN which negatively affects functional properties of an alumina composite. The invention is directed to method for making an alumina-cubic boron nitride (Al.sub.2O.sub.3-cBN) composite that contains substantially no hexagonal boron nitride (hBN) by non-conventional spark plasma sintering of cBN with nano-sized alumina particles. The invention is also directed to Al.sub.2O.sub.3-cBN/Ni composites, which contain substantially no hBN, and which exhibit superior physical and mechanical properties compared to alumina composites containing higher amounts of hBN.

The invention relates to a refractory plate for a sliding shutter for regulating a flow rate of liquid steel, to the use of a melt raw material as material in a plate of this kind and to a melt vessel for receiving liquid steel which has a plate of this kind for regulating a flow rate of liquid steel from the melt vessel.

A porous refractory cast material contains a closed refractory aggregate fraction having a minimum particle size and a maximum particle size; the ratio of maximum particle size to minimum particle size is 10:1 or less. This closed refractory aggregate fraction comprises all of the porous refractory cast material having a particle diameter greater than 0.1 mm. The porous refractory cast material also contains a binder phase containing refractory selected from calcium aluminate cement, alumina phosphate, hydratable alumina, colloidal silica and combinations thereof. Also disclosed is a metallurgical vessel with an interior lining incorporating the porous refractory cast material.

A porous refractory cast material contains a closed refractory aggregate fraction having a minimum particle size and a maximum particle size; the ratio of maximum particle size to minimum particle size is 10:1 or less. This closed refractory aggregate fraction comprises all of the porous refractory cast material having a particle diameter greater than 0.1 mm. The porous refractory cast material also contains a binder phase containing refractory selected from calcium aluminate cement, alumina phosphate, hydratable alumina, colloidal silica and combinations thereof. Also disclosed is a metallurgical vessel with an interior lining incorporating the porous refractory cast material.

This composite sintered body is a ceramic composite sintered body which includes aluminum oxide which is a main phase, and silicon carbide which is a sub-phase, the composite sintered body including an interface layer which includes, as a forming material, a material other than the aluminum oxide and the silicon carbide, at an interface between a crystal grain of the aluminum oxide and a crystal grain of the silicon carbide in a grain boundary.

This composite sintered body is a ceramic composite sintered body which includes aluminum oxide which is a main phase, and silicon carbide which is a sub-phase, the composite sintered body including an interface layer which includes, as a forming material, a material other than the aluminum oxide and the silicon carbide, at an interface between a crystal grain of the aluminum oxide and a crystal grain of the silicon carbide in a grain boundary.

Disclosed is a refractory product for casting of steel, which is capable of forming a dense surface layer which is high in terms of a slag infiltration suppressing ability and strong, in a surface region thereof efficiently or sufficiently or in an optimum state. The refractory product contains 1 mass % or more of free carbon, and 2 mass % to 15 mass % of an aluminum component as metal, with the remainder comprising a refractory material as a main composition, wherein the refractory product has a permeability of 110.sup.16m.sup.2 to 1510.sup.16m.sup.2.

It is intended to suppress flaming and smoking due to combustion of combustible substances in a certain-shaped joint material, while maintaining hot sealability of the certain-shaped joint material. A certain-shaped joint material for hot installation is obtained by: adding organic additives to a blend in a combined amount of 26 mass % to 50 mass %, with respect to and in addition to 100 mass % of the blend, wherein the blend comprises 50 mass % to 90 mass % of gibbsite type aluminum hydroxide raw material, 1 mass % to 9 mass % of clay, and 9 mass % to 23 mass % of graphite, with the remainder mainly composed of an additional refractory raw material; and subjecting the resulting mixture to kneading, forming and drying.

It is intended to suppress flaming and smoking due to combustion of combustible substances in a certain-shaped joint material, while maintaining hot sealability of the certain-shaped joint material. A certain-shaped joint material for hot installation is obtained by: adding organic additives to a blend in a combined amount of 26 mass % to 50 mass %, with respect to and in addition to 100 mass % of the blend, wherein the blend comprises 50 mass % to 90 mass % of gibbsite type aluminum hydroxide raw material, 1 mass % to 9 mass % of clay, and 9 mass % to 23 mass % of graphite, with the remainder mainly composed of an additional refractory raw material; and subjecting the resulting mixture to kneading, forming and drying.

A graphite-containing refractory has higher bending strength and fracture energy than known refractories. The graphite-containing refractory has a graphite content of 1% to 80% by mass. 1000 to 300000 carbon fibers with a fiber diameter of 1 to 45 m/fiber are bundled. The carbon fiber bundle has a length of 100 mm or more and is placed within the graphite-containing refractory to form the same.