Abstract: The invention relates to refractory materials that may be used in iron and steel metallurgy comprising, in % by weight:A! 32 to 87% of particles and/or grains of at least one refractory material, the melting temperature and thermal dissociation temperature of which are greater than 1700.degree. C.;B! 7 to 50% of an in situ-formed binding matrix and consisting of a sialon, AIN or one of its polytypes, or a mixture thereof;C! 2 to 40% of a material based on titanium nitride TiN dispersed in the matrix; and, optionally,D! 0 to 42% of hexagonal boron nitride, amorphous carbon and/or crystallized graphite dispersed in the binding matrix.

Abstract: The invention relates to refractory materials which comprise:(A) grains of at least one refractory material whose melting point and thermal decomposition temperature are higher than 1700.degree. C.;(B) a binding matrix which binds these grains together and predominantly consists of aluminum nitride AlN of hexagonal structure and/or of at least one of the polytypes of AlN; and(C) hexagonal boron nitride particles and/or crystalline graphite flakes dispersed in the binding matrix.Applications in iron and steel metallurgy, in particular as plates in a slide closure device.

Abstract: The invention relates to a refractory part for a device for regulation or interruption of a jet of steel, characterized in that it is formed from a refractory material essentially consisting ofa) 61 to 77% by weight of grains having an alumina content of more than 50% by weight and a melting point higher than 1800.degree. C., andb) 39 to 23% by weight of a binding phase having a X-ray diagram in which the most intense lines are the lines characteristic of a sialon of the formula Si.sub.6-z Al.sub.z N.sub.8-z where z ranges from 2.5 to 4.Application in particular as plate in a slide closing device.

Abstract: The invention relates to refractory materials having high resistance to corrosion, high mechanical strength at elevated temperature and high resistance to thermal shock, comprising:(A) grains of at least one refractory material whose melting point or, where appropriate, thermal decomposition temperature is higher than 1700.degree. C., these particles being dispersed in(B) a binding matrix consisting predominantly of a sialon of formula Si.sub.6-z Al.sub.z O.sub.z N.sub.8-z, where z ranges from 0.5 to 4, as determined from an X-ray diffraction pattern, wherein said refractory materials also comprise:(C) particles of hexagonal boron nitride and/or crystalline graphite dispersed in the binding matrix.Use in iron and steel metallurgy, in particular as slide closing plates, immersed nozzles, etc.

Abstract: Compound concrete composition for the manufacture of moulds, comprising: (1) a binder which comprises an alkaline-earth mineral substance, a constituent made up of fine particles of a compound other than an oxide, 90% of which have a particle size of between 1 and 150 .mu.m with a median diameter of between 3 and 20 .mu.m, these fine particles comprising particles of a substance which has a thermal conductivity higher than approximately 30 W/mK, chosen from silicon carbides, silicon carbonitrides, silicon nitrides, boron carbides, titanium carbides and tungsten carbides and a constituent made up of ultrafine particles at least 70% of which have a particle size smaller than 1 .mu.m with a median diameter of between 0.3 and 0.8 .mu.m, (2) water optionally with the addition of a dispersant, and (3) fillers comprising metal granulates and metal fibres, wherein the water/binder ratio is lower than 0.20 and the concrete composition has a thermal conductivity at 200.degree. C.

Abstract: A tuyere opening assembly of a vertical furnace or reactor includes at most four prefabricated elements made of moulded refractory concrete, and a lining therein of ceramized refractory keys of identical shape and size arranged therein for receiving a burner or a tuyere.

Abstract: The invention relates to a refractory composition comprising, by weight:(A) at least 70% of an aggregate based on refractory oxides,(B) from 7 to 25% of a matrix consisting of particles distributed between a fine fraction made up of a proportion of at least 95% of its weight of particles from 1 to 20 .mu.m in size, the median diameter of these particles being between 3 and 8 .mu.m, this fine fraction constituting 1 to 24% of the composition, and an ultrafine fraction consisting of a proportion of at least 70% of its weight of particles smaller than 1 .mu.m in size, the median diameter of these particles being between 0.3 and 0.8 .mu.m, this ultrafine fraction constituting 1 to 24% of the composition, the said matrix comprising(i) at least one oxide chosen from the group consisting of Al.sub.2 O.sub.3 and Cr.sub.2 O.sub.

Abstract: A process for the in-ladle treatment of liquid steels by injecting gas through the ladle bottom. The process comprises injecting at least one inert gas from locations which are distributed over the ladle bottom in such a way as to form at the surface of the liquid steel an annular swelling, the outside edge of which is close to the inside edge of the lining of the wall of the ladle. An oxidizing gas may be mixed with the inert gas for decarburization. The process is applied in particular to the treatment of carbon steels.

Abstract: The invention relates to new refractories with a high content of alumina and the process for their production. The refractories are made up of alumina particles held by a binder capable of withstanding a reducing atmosphere at 850.degree. C. The refractories are characterized by low porosity and high mechanical strength and are also inert towards coal ashes and slags at these temperatures. The binder used in the refractories consists of a combination of aluminum nitride and aluminum oxycarbide. The carbon required to the formation of the carbon oxide may be introduced in a form of carbon black or graphite, or may originate from a decomposition of a provisional or organic binder.