A preparation method using micro-nano bubbles as crystal seeds to induce spherical or spherical-type silver power production, said method specifically comprising the steps of: pre-adding a prepared dispersing agent solution to a reaction vessel, within the reaction vessel, simultaneously adding a prepared oxidizing solution (an aqueous solution containing silver ions or a silver ammonia solution) and a reducing solution (an aqueous solution containing one or a plurality of hydroxylamine compounds, vitamin C, formaldehyde or hydrazine hydrate), performing a reduction reaction under vigorous stirring, and using the pre-generated micro-nano bubbles within the dispersing agent solution as crystal seeds, the micro-nano bubbles crystal seeds effectively controlling the particle size of reduced silver particles throughout the reduction reaction. The method effectively controls the particle size of the silver powder during production, and also controls the crystal nucleus growth rate and dispersibility.

An electrically-conductive material containing Ag in an amount of 10 mass % or more and 70 mass % or less, Pd in an amount of 30 mass % or more and 90 mass % or less, Ni in an amount of more than 5 mass % and 45 mass % or less, and inevitable impurities. A ratio of a Ni content (mass %) to a Ag content (mass %) (Ni (mass %)/Ag (mass %)) is 0.1 or more and 5.0 or less, metal structures include a AgPd alloy phase and a PdNi alloy phase, and a volume ratio of the PdNi alloy phase is 18 vol % or more and 80 vol % or less. Ni is added in a high concentration to a AgPd alloy, and the amount of PdNi alloy phases generated as separate phases is controlled to strengthen the entire alloy.

A method for producing a porous member, whereby a member having smaller microgaps can be produced, and additionally, the outermost surface alone can be made porous and a porous layer can be formed on the surface while maintaining the characteristics of portions in which no porous layer is formed, is provided.

A method for producing a porous member, whereby a member having smaller microgaps can be produced, and additionally, the outermost surface alone can be made porous and a porous layer can be formed on the surface while maintaining the characteristics of portions in which no porous layer is formed, is provided.

Fine metal particles of any one of Ag, Cu or Zn having a dispersing agent that is coordinated on the surfaces thereof, the dispersing agent having an acid value and an amine value which are both in a range of 0 to 20 mgKOH/g (wherein when either the acid value or the amine value is 0, the other one is not 0), and a dispersion solution in which the fine metal particles are dispersed. The fine metal particles and the dispersion solution containing the fine metal particles can be diluted with various kinds of solvents of either the water type or the organic type, and feature excellent dispersion property even after having been diluted.

Provided are a silver article formed using pure silver, which has high Vickers hardness and prohibits the occurrence of metal corrosion and the occurrence of discoloration; and its method. Disclosed are a silver article and its method, wherein the Vickers hardness is adjusted to 60 HV or higher, and when the height of the peak of 2θ=38°±0.2° by an XRD is designated as h1, and that of 2θ=44°±0.4° is designated as h2, h2/h1 is adjusted to 0.2 or greater.

Provided are a silver article formed using pure silver, which has high Vickers hardness and prohibits the occurrence of metal corrosion and the occurrence of discoloration; and its method. Disclosed are a silver article and its method, wherein the Vickers hardness is adjusted to 60 HV or higher, and when the height of the peak of 2θ=38°±0.2° by an XRD is designated as h1, and that of 2θ=44°±0.4° is designated as h2, h2/h1 is adjusted to 0.2 or greater.

A sliding contact material that is used for a constituent material, particularly a brush, of a motor. The sliding contact material includes: Pd in an amount of 20.0% by mass or more and 50.0% by mass or less; Ni and/or Co in an amount of 0.6% by mass or more and 3.0% by mass or less in terms of a total concentration; and Ag and inevitable impurities as a balance. Preferably, the sliding contact material further contains an additive element M including at least one of Sn and In, and the total concentration of the additive element M is 0.1% by mass or more and 3.0% by mass or less. When containing the additive element M, the sliding contact material has material structures in which composite dispersed particles containing an intermetallic compound of Pd and the additive element M are dispersed in an Ag alloy matrix, and the ratio (K.sub.Pd/K.sub.M) of the content (% by mass) of Pd and the content (% by mass) of the additive element M in the composite dispersed particles is within a range of 2.4 or more and 3.6 or less.

A sliding contact material that is used for a constituent material, particularly a brush, of a motor. The sliding contact material includes: Pd in an amount of 20.0% by mass or more and 50.0% by mass or less; Ni and/or Co in an amount of 0.6% by mass or more and 3.0% by mass or less in terms of a total concentration; and Ag and inevitable impurities as a balance. Preferably, the sliding contact material further contains an additive element M including at least one of Sn and In, and the total concentration of the additive element M is 0.1% by mass or more and 3.0% by mass or less. When containing the additive element M, the sliding contact material has material structures in which composite dispersed particles containing an intermetallic compound of Pd and the additive element M are dispersed in an Ag alloy matrix, and the ratio (K.sub.Pd/K.sub.M) of the content (% by mass) of Pd and the content (% by mass) of the additive element M in the composite dispersed particles is within a range of 2.4 or more and 3.6 or less.

Methods for producing silver nanostructures with improved dimensional control, yield, purity, monodispersed, and scale of synthesis.