A process comprising: (i) coating particles of silicon carbide, silicon nitride, boron carbide or boron nitride with a metal alloy or metal layer; (ii) agglomerating the particles of step (i); thermally spraying the agglomerated metal or metal alloy coated particles onto a substrate to provide a coating thereon.

A process comprising: (i) coating particles of silicon carbide, silicon nitride, boron carbide or boron nitride with a metal alloy or metal layer; (ii) agglomerating the particles of step (i); thermally spraying the agglomerated metal or metal alloy coated particles onto a substrate to provide a coating thereon.

There are provided a spherical silver powder which has the same diameter as that of a spherical silver powder produced by a conventional wet reduction method and which can sufficiently sinter the silver particles thereof to cause the silver particles to be adhered to each other at a relatively low temperature to form a conductive film having a low volume resistivity when it is used for a baked type conductive paste, and a method for producing the same. A spherical silver powder, which contains a neutral or basic amino acid having a carbon number of not less than 5 in each of particles thereof and which has an average particle diameter D.sub.50 of 0.2 to 5 μm based on a laser diffraction method, is produced by adding the neutral or basic amino acid having the carbon number of not less than 5 (such as proline, tyrosine, tryptophan, phenylalanine, arginine or histidine) to a water reaction system containing silver ions to mix a reducing agent therewith to deposit silver particles by reduction.

There are provided a spherical silver powder which has the same diameter as that of a spherical silver powder produced by a conventional wet reduction method and which can sufficiently sinter the silver particles thereof to cause the silver particles to be adhered to each other at a relatively low temperature to form a conductive film having a low volume resistivity when it is used for a baked type conductive paste, and a method for producing the same. A spherical silver powder, which contains a neutral or basic amino acid having a carbon number of not less than 5 in each of particles thereof and which has an average particle diameter D.sub.50 of 0.2 to 5 μm based on a laser diffraction method, is produced by adding the neutral or basic amino acid having the carbon number of not less than 5 (such as proline, tyrosine, tryptophan, phenylalanine, arginine or histidine) to a water reaction system containing silver ions to mix a reducing agent therewith to deposit silver particles by reduction.

The present disclosure relates to a silver powder preparation method comprising: a silver powder preparation step of preparing a silver salt, which comprises silver ions, and then reducing the silver ion so as to precipitate silver particles; a silver powder recovery step of separating silver particles from an aqueous solution or a slurry, which comprises the precipitated silver particles, and then washing and drying same to recover silver powder; and a silver powder coating step of injecting a pH adjuster into the recovered silver powder to adjust the pH, and then injecting a coating agent to coat after the pH adjustment. The pH adjuster is used in the silver powder coating step to adjust the pH, and thus, when silver power is used in a conductive paste, as the rate of change in viscosity over time is low, a conductive paste having excellent viscosity stability can be provided.

The present disclosure relates to a silver powder preparation method comprising: a silver powder preparation step of preparing a silver salt, which comprises silver ions, and then reducing the silver ion so as to precipitate silver particles; a silver powder recovery step of separating silver particles from an aqueous solution or a slurry, which comprises the precipitated silver particles, and then washing and drying same to recover silver powder; and a silver powder coating step of injecting a pH adjuster into the recovered silver powder to adjust the pH, and then injecting a coating agent to coat after the pH adjustment. The pH adjuster is used in the silver powder coating step to adjust the pH, and thus, when silver power is used in a conductive paste, as the rate of change in viscosity over time is low, a conductive paste having excellent viscosity stability can be provided.

Provided is a method of producing spherical silver powder, which makes it possible to easily produce spherical silver powder having primary particle diameters with less variation than conventional powder and spherical silver powder obtained by the method. The method of producing spherical silver powder includes a reduction precipitation step of precipitating silver particles by reduction by adding a reductant including hydrazine carbonate to an aqueous reaction system containing silver ions.

Provided is a method of producing spherical silver powder, which makes it possible to easily produce spherical silver powder having primary particle diameters with less variation than conventional powder and spherical silver powder obtained by the method. The method of producing spherical silver powder includes a reduction precipitation step of precipitating silver particles by reduction by adding a reductant including hydrazine carbonate to an aqueous reaction system containing silver ions.

Provided are gold-coated flat silver particles, a dispersion including the gold-coated flat silver particles and a dispersion medium, a method of the dispersion, a coating film including the gold-coated flat silver particles, and an antireflection optical member. The gold-coated flat silver particles include flat silver particles and a gold coating layer, in which an average thickness of the gold coating layer on principal planes of the particles is 0.1 nm to 2 nm, and a ratio of the average thickness of the gold coating layer on the principal planes of the particles to an average thickness of the gold coating layer on edge surfaces of the particles is 0.02 or higher.

Provided are gold-coated flat silver particles, a dispersion including the gold-coated flat silver particles and a dispersion medium, a method of the dispersion, a coating film including the gold-coated flat silver particles, and an antireflection optical member. The gold-coated flat silver particles include flat silver particles and a gold coating layer, in which an average thickness of the gold coating layer on principal planes of the particles is 0.1 nm to 2 nm, and a ratio of the average thickness of the gold coating layer on the principal planes of the particles to an average thickness of the gold coating layer on edge surfaces of the particles is 0.02 or higher.