Abstract: A composite material having a first metallic material as the matrix material and extremely fine particles of diameters of the order of tens to hundreds of angstroms of a second metal dispersed in this metallic matrix material is obtained by rapidly adiabatically cooling vapor of the second metallic material through a nozzle, and squirting a jet of fine particles produced thereby into a molten mass of the first material. Optionally, inert gas may be squirted through the nozzle along with the vapor of the second metallic material.

Abstract: A ceramic surface-metallic core particle composite fine powder material is disclosed, composed of fine particles each having a metallic core and a ceramic surface layer, in which the average value of the ratio of the thickness of the surface layer of a powder particle to the radius of the particle is subtantially greater than 0.05. A method and an apparatus for making this material from core metal and a gas which combines with the core metal to form the ceramic outer layer are also described, in which a gaseous mixture of vapor of the core metal and the gas is passed through a convergent-divergent nozzle and is thereby rapidly cooled by adiabatic expansion so that the core metal as it solidifies forms metal cores for fine particles while the gas reacts with the outer layers of these particles to form ceramic surface layers.

Abstract: A composite fine powder material is made of first particles with average particle diameter less than or equal to about ten microns, each having a composite structure and being made up of a plurality of fine second particles of a ceramic made by reacting together a first metal and a gas, embedded in a matrix of a second metal. This composite fine powder material is made by vaporizing the first metal, mixing the vapor with the gas, expanding the mixture through a first nozzle mechanism for providing adiabatic expansion cooling under reaction between the first metal and the gas to provide the fine second particles of ceramic, producing vapor of the second metal and mixing it in with the fine second particles at the downstream of the first nozzle mechanism, directing the resulting mixture through a second expansion nozzle mechanism to form the first particles of composite structure, and then collecting these first particles.

Abstract: A magnetic fluid having a base liquid and magnetic particles with so small average particle diameter as to be of some hundreds of angstroms dispersed in the base liquid. Such a magnetic fluid is produced by ejecting a molten magnetic metal adiabatically from an expansion nozzle against a bath of a base liquid.

Abstract: A composite material made of a matrix of a first metal and reinforcing first particles with average particle diameter less than or equal to about ten microns dispersed in the first metal matrix, with the reinforcing first particles each having a composite structure, being made up of a plurality of fine second particles of a ceramic made by reacting together a second metal and a gas and being combined with one another by a matrix of a third metal.

Abstract: Fine powder of a metal is made by vaporizing the metal in a vaporization chamber, mixing the metallic vapor with an inert carrier gas, and then adiabatically expanding the mixture through a nozzle, which preferably is a convergent-divergent nozzle. A jet flow from the nozzle is very rapidly cooled by this adiabatic expansion, which quickly condenses the metal vapor in the jet flow into very fine particles. Optionally the jet flow is directed against a metal powder collecting means, which may be a collection plate, but preferably is a bath of oil which entrains the particles and keeps them from agglomerating together by partially neutralizing their surface activity. Thus fine metal powder with particle diameters of the order of a few hundreds of angstroms can be economically produced.

Abstract: Fine powder of an alloy of two or more metals is made by vaporizing each of these metals in its own vaporization chamber, mixing each of the metallic vapors with an inert carrier gas, and then adiabatically expanding each of the mixture gases through its own nozzle, which preferably is a convergent-divergent nozzle. Jet flows from the nozzles are collided together, after having been very rapidly cooled by this adiabatic expansion, and thereby the metal vapors in the jet flows are quickly condensed into very fine alloy particles. Optionally the combined flows from the jets are directed against an alloy powder collecting means, which may be a collection plate, but preferably is a bath of oil which entrains the alloy particles and keeps them from agglomerating together by partially neutralizing their surface activity. Thus fine alloy powder with particle diameters of the order of a few hundreds of angstroms can be economically produced.

Abstract: A ceramic surface-metallic core particle composite fine powder material is disclosed, composed of fine particles each having a metallic core and a ceramic surface layer, in which the average value of the ratio of the thickness of the surface layer of a powder particle to the radius of the particle is substantially greater than 0.05. A method and an apparatus for making this material from core metal and a gas which combines with the core metal to form the ceramic outer layer are also described, in which a gaseous mixture of vapor of the core metal and the gas is passed through a convergent-divergent nozzle and is thereby rapidly cooled by adiabatic expansion so that the core metal as it solidifies forms metal cores for fine particles while the gas reacts with the outer layers of these particles to form ceramic surface layers.

Abstract: A composite material including matrix metal and ceramic surface - metallic core fine powder material is disclosed, composed of fine particles each having a metallic core and a ceramic surface layer, in which the average value of the ratio of the thickness of the surface layer of a powder particle to the radius of the particle is substantially greater than 0.05, dispersed within a matrix of matrix metal.

Abstract: A mixture gas containing metallic vapor with oxidizing gas produced by reducing of the oxide of the metal at high temperature is led, at a high enough temperature and a low enough pressure for the reverse oxidization reaction between them to not substantially take place, into a convergent-divergent nozzle, and squirts out from the nozzle, as cooled down rapidly by adiabatic expansion in the nozzle to a low enough temperature for the oxidization reaction between them to not substantially take place, to be led to the surface of a pool of molten retrieving metal, either directly or via deceleration. The retrieving pool metal may be the same kind as the metallic vapor to be retrieved, or may be different. When the metallic vapor to be retrieved is magnesium vapor, the retrieving metal of the different kind may be lead, bismuth, tin, antimony, or a mixture thereof.

Abstract: A method of making a fine powder of a metal and another element in an intimate mutual relation such as an alloy or a chemical compound of a metal and a non metallic element, wherein a gaseous mixture of the metal and the other element is passed through a convergent-divergent nozzle and is thereby rapidly cooled by adiabatic expansion so that the metal and the other element react with each other while the resulting alloy or chemical compound is solidified to form fine particles.

Abstract: A process for manufacture of metallic magnesium. A mixture of a first quantity of magnesium oxide, a second quantity of a carbide forming material which is either a material selected from the group of materials consisting of calcium, aluminum, boron, silicon, calcium oxide, aluminum oxide, boron oxide, and silicon oxide, or is a mixture of two or more of these materials, and whose weight is 10% or less than the weight of the first quantity, and a third quantity of carbon which is at least the equivalent mol weight of that of the magnesium oxide plus the carbide forming material, is heated within a reducing furnace at a pressure between about 5 and 200 torr and at a temperature of at least 1600.degree. C.

Abstract: An oxygen sensor consisting of a metal electrode formed on the surface of the side to be measured of a solid electrolyte sintering and of a reference oxygen pole formed by a mixture of metal and metal oxide on the opposite side of said surface of the side to be measured of the solid electrolyte sintering body, characterized in that, at least over the whole surface adjoining the mixture of metal and metal oxide on the side of the reference oxygen pole of the solid electrolyte sintering, a porous metal electrode is formed to insulate the solid electrolyte sintering from the mixture of metal and metal oxide, thereby improving the low temperature performance and internal impedance characteristics, as well as prolonging the life thereof. A method for manufacturing this sensor is also provided.