A processing device for a metal material, containing: an airtight container for housing a specimen thereinside; an oxygen pump for extracting oxygen molecules from a gas discharged from the airtight container; a circulation means for returning the gas into the airtight container; and a plasma generation means present inside the airtight container for converting the gas returned from the circulation means into plasma and exposing the specimen thereto.

A method of forming cemented tungsten tetraboride, by combining tungsten and boron in a molar ratio of from about 1:6 to about 1:12, respectively, and firing the combined tungsten and boron in a hexagonal boron nitride crucible at a temperature of from about 1600 C to about 2000 C, to form tungsten tetraboride, milling the tungsten tetraboride to a powder, adding a metal binder to the tungsten tetraboride powder to produce a metal-tungsten tetraboride mixture, compressing the metal-tungsten tetraboride mixture, and sintering the compressed metal-tungsten tetraboride mixture to form cemented tungsten tetraboride.

A method of forming cemented tungsten tetraboride, by combining tungsten and boron in a molar ratio of from about 1:6 to about 1:12, respectively, and firing the combined tungsten and boron in a hexagonal boron nitride crucible at a temperature of from about 1600 C to about 2000 C, to form tungsten tetraboride, milling the tungsten tetraboride to a powder, adding a metal binder to the tungsten tetraboride powder to produce a metal-tungsten tetraboride mixture, compressing the metal-tungsten tetraboride mixture, and sintering the compressed metal-tungsten tetraboride mixture to form cemented tungsten tetraboride.

Provided is a simple, fast, scalable, and environmentally benign method of producing a graphene-reinforced inorganic matrix composite directly from a graphitic material, the method comprising: (a) mixing multiple particles of a graphitic material and multiple particles of an inorganic solid carrier material to form a mixture in an impacting chamber of an energy impacting apparatus; (b) operating the energy impacting apparatus with a frequency and an intensity for a length of time sufficient for peeling off graphene sheets from the graphitic material and transferring the graphene sheets to surfaces of solid inorganic carrier material particles to produce graphene coated or graphene-embedded inorganic particles inside the impacting chamber; and (c) forming graphene-coated or graphene-embedded inorganic particles into the graphene-reinforced inorganic matrix composite. Also provided is a mass of the graphene-coated or graphene-embedded inorganic particles produced by this method.

Provided is a simple, fast, scalable, and environmentally benign method of producing a graphene-reinforced inorganic matrix composite directly from a graphitic material, the method comprising: (a) mixing multiple particles of a graphitic material and multiple particles of an inorganic solid carrier material to form a mixture in an impacting chamber of an energy impacting apparatus; (b) operating the energy impacting apparatus with a frequency and an intensity for a length of time sufficient for peeling off graphene sheets from the graphitic material and transferring the graphene sheets to surfaces of solid inorganic carrier material particles to produce graphene coated or graphene-embedded inorganic particles inside the impacting chamber; and (c) forming graphene-coated or graphene-embedded inorganic particles into the graphene-reinforced inorganic matrix composite. Also provided is a mass of the graphene-coated or graphene-embedded inorganic particles produced by this method.

A polycrystalline bulk body of this invention has uniformity in superconducting properties, in comparison to a polycrystalline bulk body including crystal grains each constituted by (Ba.sub.1-xK.sub.x)Fe.sub.2As.sub.2. A polycrystalline bulk body (1) of this invention includes crystal grains each constituted by an iron-based compound (10) expressed by chemical formula AA′Fe.sub.4As.sub.4, where A is Ca and A′ is K, the iron-based compound (10) having a crystal structure in which AFe.sub.2As.sub.2 layers (16) and A′Fe.sub.2As.sub.2 layers (17) are alternately stacked.

A polycrystalline bulk body of this invention has uniformity in superconducting properties, in comparison to a polycrystalline bulk body including crystal grains each constituted by (Ba.sub.1-xK.sub.x)Fe.sub.2As.sub.2. A polycrystalline bulk body (1) of this invention includes crystal grains each constituted by an iron-based compound (10) expressed by chemical formula AA′Fe.sub.4As.sub.4, where A is Ca and A′ is K, the iron-based compound (10) having a crystal structure in which AFe.sub.2As.sub.2 layers (16) and A′Fe.sub.2As.sub.2 layers (17) are alternately stacked.

The present invention relates to a device (1) for sintering by pulsating current, the device (1) comprising: —a sintering cell (4) comprising two walls (14a, 14b) facing each other and defining between them a cavity (C) for receiving material to be sintered, —a press (2) arranged for moving one of the walls (14a, 14b) towards the other wall, so as to compress the material, when the material is received in the cavity (C), —means (10a, 10b) of rotating one of the walls (14a, 14b) relative to the other wall, so as to apply a torsional force to the material, when the material is compressed in the cavity (C).

The present invention relates to a device (1) for sintering by pulsating current, the device (1) comprising: —a sintering cell (4) comprising two walls (14a, 14b) facing each other and defining between them a cavity (C) for receiving material to be sintered, —a press (2) arranged for moving one of the walls (14a, 14b) towards the other wall, so as to compress the material, when the material is received in the cavity (C), —means (10a, 10b) of rotating one of the walls (14a, 14b) relative to the other wall, so as to apply a torsional force to the material, when the material is compressed in the cavity (C).

A method of sintering electrically conducting powders in an air atmosphere for obtaining a sintered product includes the following step sequence: placing the powders in an electrically isolating mold, applying a pressure to the powders between 100 and 500 MPa, and applying to the powders a sintering current at a sintering voltage during a sintering time, for sintering the powders. Before applying the sintering current density to the powders, an activation current density is lower than the sintering current density at an activation voltage greater than the sintering voltage during an activation time lower than the sintering time, to reduce the electrical resistance of the powders.