A problem is to provide a silver paste which can produce, without variation in resistivity value, a conductive silver coating film exhibiting resistivity substantially equivalent to the resistance value of bulk silver in low-temperature sintering. The problem is solved by providing a silver paste including a silver nanoparticle aqueous dispersion prepared by using a compound having a polyethyleneimine skeleton as a protective agent, a compound having a functional group reactable with nitrogen atoms in the polyethyleneimine, and at least one compound selected from the group consisting of a compound having an amine functional group and a compound having an amide functional group.

Provided is an ink for use in electronic component production making use of screen printing, which is suitable for actually allowing fine lines with high precision to be drawn in screen printing, and for actually allowing successive screen printing operations to be performed. The ink for screen printing of the present invention includes surface-modified silver nanoparticles (A) and a solvent (B), and has a viscosity at a shear rate of 10 (1/s) and 25° C. of 60 Pa.Math.s or more. The surface-modified silver nanoparticles (A) each include a silver nanoparticle and an amine-containing protective agent coating the silver nanoparticle. The solvent (B) includes at least a terpene solvent. In solvent (B), a content of solvents having a boiling point of less than 130° C. is 20 wt % or less based on the total amount of solvents.

A method, and systems in which such method may be practiced, allow for the separation of elemental metals from metal alloy. A metal alloy is atomized to form metal alloy particulates. The metal alloy particulates are exposed to an oxidizing agent, such as chlorine gas in the presence of a salt, such as NaCl, an acid, such as HCl, and water. The resulting solution may be filtered to remove particulates, reduced, filtered, reduced, filtered, and so on. In aspects, the method is used to refine gold alloy by oxidation of elemental sponge gold to gold chloride followed by reduction to pure elemental gold.

A preparation method for a silver-metal oxide electrical contact material, comprising: (1) mixing a silver-containing precursor solution with a metal oxide precursor solution; (2) reacting a reducing agent with the mixed solution to obtain silver powder coated with a metal oxide precursor; (3) heat treating the silver powder in a non-reducing atmosphere to obtain the silver-metal oxide electrical contact material. A preparation device for a silver-metal oxide electrical contact material, a silver-metal oxide electrical contact material prepared by the preparation method, and an electrical contact prepared by the silver-metal oxide electrical contact material. The electrical contact material prepared by the preparation method is at nanoscale, significantly prolonging electrical endurance of the electrical contact.

A silver powder includes a large number of particles. The particles include polyhedral particles 2. The ratio P1 of the number of the polyhedral particles 2 to the total number of the particles is equal to or greater than 80%. Each polyhedral particle 2 has a body containing silver as a main component, and a coating layer covering a surface of the body and containing organic matter as a main component. Each polyhedral particle 2 has an aspect ratio of equal to or less than 3.0. The content P2 of the organic matter in the silver powder is preferably equal to or less than 0.5% by weight. The silver powder preferably has a median diameter D50 of equal to or less than 0.5 μm. The silver powder preferably has a tap density TD of equal to or greater than 5.0 g/cm.sup.3.

[Object] To provide fine particles 2 having good printing characteristics, good thermal conductivity, and good electrical conductivity.

[Solution] The fine particles 2 are flake-like. A main component of the fine particles 2 is an electrically conductive metal. A typical metal is silver. A particle diameter D50 of particles including a large number of the fine particles 2 is equal to or greater than 0.10 μm but equal to or less than 0.50 μm, a particle diameter D95 of the particles is equal to or less than 1.00 μm, and a maximum particle diameter Dmax of the particles is equal to or less than 3.00 μm. A particle diameter D10 of the particles is equal to or greater than 0.05 μm. A BET specific surface area of the particles is equal to or greater than 2.0 m.sup.2/g. A tap density TD of the particles is equal to or greater than 2.0 g/cm.sup.3. An average Tave of thicknesses of the fine particles 2 is equal to or less than 0.05 μm.

There is disclosed an article which is formed of a solid-phase or liquid-phase sintered product of a metal powder, ceramic powder or glass powder. For manufacturing the article, an extrudable mixture which contains the material powder and a thermoplastic binder is shaped into a continuous filament suitable for use in fused filament 3D printers. The printed object is then invested in plaster or other castable refractory. The invested object is then subjected to heating. The heating process burns off the thermoplastic binder and sinters the powders of metal, glass or ceramic, leaving a pure metal, glass or ceramic object.

The extrudable mixture is produced by preparing a material powder, preparing thermoplastic binder, blending the material powder and the thermoplastic binder together. The most preferable extrudable mixture contains 80 to 92% by weight of metal powder, 8 to 20% by weight of thermoplastic binder, and 0.0 to 0.1% unavoidable impurities. The extrudable mixture is then extruded into a continuous filament suitable for use in various 3d printing hardware.

The invention includes apparatus and methods for instantiating precious metals in a nanoporous carbon powder.

Composite compositions comprising metal nanoparticles and/or microparticles and a binder are provided. Composites are tunable to achieved specific desired characteristics, such as sintering temperature, melting temperature, print resolution, and surface binding capabilities. Preferably, the metal particles may be produced using plasma-based technology. The composites are spreadable or printable and are especially useful in the field of electronics. The composites are capable of being used to form highly conductive wires or traces in electronic components. Preferably, the resulting metal structure has a low level of metal oxidation. The disclosure also includes methods for producing composite materials.

The present invention provides a silver coating composition that develops excellent conductivity (low resistance value) by low-temperature and short-time calcining, and that is excellent in fine-line drawing performance and suitable for intaglio offset printing. A silver particle coating composition comprising: silver nano-particles (N) whose surfaces are coated with a protective agent containing an aliphatic hydrocarbon amine; a surface energy modifier; and a dispersion solvent. The surface energy modifier may be selected from the group consisting of a silicon-based surface energy modifier and an acrylic surface energy modifier. The coating composition preferably further comprises silver microparticles (M). The silver coating composition is suitable for intaglio offset printing.