Abstract: Abrasive particles from the group of conventional abrasive particles, in particular fused or sintered corundums, zirconium corundums, silicon corundums, silicon carbides and boron carbide, for application in synthetic resin-bonded abrasives, characterized by the fact that on the surface they are provided with a coating consisting of 0.05 to 2.0 weight percent, relative to the weight of the untreated abrasive particle, of an aqueous binding agent on silicon basis and 0.05 to 5.0 weight percent, also relative to the weight of the untreated abrasive particle, of a complex, fine grained oxide compound of the general formula AxByOz, with A and B each being a group of elements and O being oxygen present in a stoichiometric ratio to A and B, and whereby the numbers x, y and z denote the composition of the complex oxides without being limited to whole numbers, and z corresponds to a product of the sum of (x+y) and a factor of between 1.5 and 2.5.

Abstract: An Al2O3 and ZrO2 based abrasive grain containing titanium compounds in a reduced form, especially in the form of oxides and/or suboxides and/or carbides and/or oxycarbides and/or oxycarbonitrides and/or silicides, corresponding to a proportion of 0.510 wt %, expressed as TiO2, containing 20-50 wt % ZrO2, wherein more than 75 wt. % of the ZrO2 is present in a tetragonal crystal form, having an overall carbon content of 0.03-0.5 wt. %, a proportion of impurities caused by raw materials of less than 3.0 wt %, wherein the rare earth content calculated in the form of oxides is less than 0.1 wt %, having an Si-compound content of 0.05-1.0 wt %, expressed as SiO2, and an Al2O3 content of 50-80 wt.

Abstract: An Al2O3 and ZrO2 based abrasive grain containing titanium compounds in a reduced form, especially in the form of oxides and/or suboxides and/or carbides and/or oxycarbides and/or oxycarbonitrides and/or suicides, corresponding to a proportion of 0.510 wt. %, expressed as TiO2, containing 20–50 wt. % ZrO2, wherein more than 75 wt. % of the ZrO2 is present in a tetragonal crystal form, having an overall carbon content of 0.03–0.5 wt. %, a proportion of impurities caused by raw materials of less than 3.0 wt. %, wherein the rare earth content calculated in the form of oxides is less than 0.1 wt. %, having an Si-compound content of 0.05–1.0 wt. %, expressed as SiO2, and an Al2O3 content of 50–80 wt.

Abstract: Abrasive particles from the group of conventional abrasive particles, in particular fused or sintered corundums, zirconium corundums, silicon corundums, silicon carbides and boron carbide, for application in synthetic resin-bonded abrasives, characterized by the fact that on the surface they are provided with a coating consisting of 0.05 to 2.0 weight percent, relative to the weight of the untreated abrasive particle, of an aqueous binding agent on silicon basis and 0.05 to 5.0 weight percent, also relative to the weight of the untreated abrasive particle, of a complex, fine grained oxide compound of the general formula AxByOz, with A and B each being a group of elements and O being oxygen present in a stoichiometric ratio to A and B, and whereby the numbers x, y and z denote the composition of the complex oxides without being limited to whole numbers, and z corresponds to a product of the sum of (x+y) and a factor of between 1.5 and 2.5.

Abstract: An Al2O3 and ZrO2 based abrasive grain containing titanium compounds in a reduced form, especially in the form of oxides and/or suboxides and/or carbides and/or oxycarbides and/or oxycarbonitrides and/or suicides, corresponding to a proportion of 0.510 wt. %, expressed as TiO2, containing 20-50 wt. % ZrO2, wherein more than 75 wt. % of the ZrO2 is present in a tetragonal crystal form, having an overall carbon content of 0.03-0.5 wt. %, a proportion of impurities caused by raw materials of less than 3.0 wt. %, wherein the rare earth content calculated in the form of oxides is less than 0.1 wt. %, having an Si-compound content of 0.05-1.0 wt. %, expressed as SiO2, and an Al2O3 content of 50-80 wt.

Abstract: The invention relates to a method for heat-treating fine-grained materials which tend to agglomerate at high temperatures and which have an average grain size of preferably 0 to 1000 &mgr;m within temperature ranges around and above the agglomeration temperature, in a fluidized bed of another, coarse-grained material. The temperature range in which the coarse-grained material tends to agglomerate and sinter to the reactor walls is higher than that of the fine-grained material. The coarse-grained material used is a material of the same type, a similar type or a different type with an average grain size of 1 to 10 mm. The fine-grained material is fed in directly over the tuyere bottom of a closed furnace chamber containing the fluidized bed, performs a circulating movement in said fluidized bed and once the heat treatment has been carried out, is pneumatically withdrawn from the fluidized bed into the top section of the furnace, and cooled immediately.

Abstract: The present invention relates to a method for producing an abrasive grain from a hard-material alloy based on titanium carbide, with alloying contributions from the group of carbides, nitrides, and/or borides from the secondary groups IVb, Vb, and VIb of the periodic system.

Abstract: The present invention pertains to a process for preparing an abrasive based on corundum with a grain shape factor exceeding 0.6.

Abstract: A spherical powder selected from the group consisting of titanium nitride, titanium carbonitride, titanium nitride containing a metal of the IVa, Va and VIa group of the periodic table, and titanium carbonitride containing a metal of the IVa, Va and VIa group of the periodic table, having an average grain size of more than 2 .mu.m and a narrow grain spectrum, is prepared by introducing into a reaction vessel a mixture of at least one substance selected from the group consisting of titanium metal, a metal of the IVa, Va and VIa group of the periodic table, and an oxide, carbide, nitride and carbonitride of said metals, and a carbon-containing substance, establishing a nitrogen atmosphere in the reaction vessel, heating the mixture in the reaction vessel to a temperature between 800.degree. C. and 2400.degree. C. and maintaining the temperature between 1400.degree. C. and 2000.degree. C.

Abstract: The invention relates to a method for producing fine grained, sintering active nitride and/or carbonitride powder of titanium as well as, optionally, of other metals of the IVA, VA and VIA group of the periodic table of elements. In order to achieve, without any considerable comminution, a grain of high purity with a low grain size, the following steps are performed:The introduction into the reactor of a reaction mixture consisting of oxides of titanium and, optionally, of other metals of the IVA, VA and VIA group of the periodic system and a carbonaceous material;providing a nitrogen atmosphere in the reactor at a decreased pressure;heating the content of the reactor to a temperature of between 800.degree. C. and 2000.degree. C., preferably between 1000.degree. C. and 1900.degree. C., and keeping the temperature within a range of between 1400.degree. C. and 1800.degree. C.

Abstract: The invention relates to a process for the production of rare earth metals and alloys thereof. The process exploits the known advantages of metallothermal reduction techniques while decisively enhancing their reduction process. Rare earth halides and/or rare earth oxides are reduced in an electric arc furnace by means of one or several alkaline earth metals, preferably, calcium. Additives such as iron metals or other alloying elements, alkali- and/or alkaline earth metal salt, may be added to the electric arc furnace in a two-phase furnace operation. The reduction takes place in an atmosphere inert to rare earth metals, rare earth compounds, and alkaine earth metals. Agitation is produced in the metal in the furnace by eletromagnetic forces caused by a suitably selected current-to-voltage ratio for the electric arc, in order to achieve reduction in the shortest possible time and as completely as possible.

Abstract: A method of producing a grinding medium on the basis of alpha-alumina and at least one alumina carbide selected from the group consisting of Al.sub.2 OC and Al.sub.4 O.sub.4 C comprises the steps of melting a mixture of alumina or a material rich in alumina with a carbon-containing reducing agent to obtain a melt, rapidly cooling the melt to obtain a solidified body, breaking the solidified body into abrasive grains, and subjecting the abrasive grains to a heat treatment at a temperature of 500.degree. C. and 1500.degree. C. for a period of three minutes to 24 hours.

Abstract: An abrasive material is prepared from a starting material comprised of a spent metallic catalyst on an alumina carrier by melting the starting material with a reducing agent to obtain a melt consisting of a melt component including the alumina on an alloy residue, cooling the melt at a speed correlated with a desired crystallite size of the abrasive material to be obtained, and mechanically separating the melt component from the alloy residue before or after solidification, the melt component constituting the abrasive material.

Abstract: Flint is produced from a mischmetal and iron melt by permitting the alloy melt to cool in a mold at a slow enough rate that, as the solidification point of the melt is approached, its temperature is maintained at 800.degree.-600.degree. C for at least 10 minutes. The alloy melt is subsequently extruded and the extrudate is subjected to a heat treatment at temperatures from 370.degree.-470.degree. C for 1/2 to 4 hours, the heat treatment being discontinued before the limit value of the thermodynamic equilibrium has been reached.

Abstract: Abrasive granules are produced from alumina or an alumina-zirconia mixture by melting the oxide material and rapidly cooling the melt. To control the solidification velocity, the melt is cast into a molten chloride of Na, Ca, Ba, Mg or mixtures thereof to cool the oxide material melt, the chloride is separated from the cooled and solidified oxide material, and thereafter abrasive granules are produced from the solidified oxide material.