An object of the present invention to provide copper fine particles which can be sintered at a lower temperature than that of the conventional copper fine particles without causing a cost increase, a decrease in productivity, a method for producing the copper fine particles, and a sintered body, and the present invention provides copper fine particles having a coating film containing cuprous oxide and copper carbonate on the surface thereof.

The present invention discloses a method for fabricating a porous spherical iron-based alloy powder, a powder thereof and a sintered body thereof. The method comprises steps: mixing an iron oxide powder and an alloying powder to form a mixed powder;

spray-granulating the mixed powder to form a spherical spray-granulated powder; and placing the spherical spray-granulated powder in a reducing environment and heating it to a temperature of lower than 700° C. to obtain a porous spherical iron-based alloy powder having high flowability, high compressibility, superior sinterability and low cost.

The present invention discloses a method for fabricating a porous spherical iron-based alloy powder, a powder thereof and a sintered body thereof. The method comprises steps: mixing an iron oxide powder and an alloying powder to form a mixed powder;

spray-granulating the mixed powder to form a spherical spray-granulated powder; and placing the spherical spray-granulated powder in a reducing environment and heating it to a temperature of lower than 700° C. to obtain a porous spherical iron-based alloy powder having high flowability, high compressibility, superior sinterability and low cost.

The present invention discloses a method for fabricating a porous spherical iron-based alloy powder, a powder thereof and a sintered body thereof. The method comprises steps: mixing an iron oxide powder and an alloying powder to form a mixed powder;

spray-granulating the mixed powder to form a spherical spray-granulated powder; and placing the spherical spray-granulated powder in a reducing environment and heating it to a temperature of lower than 700° C. to obtain a porous spherical iron-based alloy powder having high flowability, high compressibility, superior sinterability and low cost.

A Ta-Nb alloy powder which has provides a capacitor having a higher capacitance than a Ta capacitor and a better thermal stability in terms of an oxide film is better than a Nb capacitor, the Ta-Nb alloy powder being a Ta-Nb alloy powder produced by a thermal CVD method, wherein a content of Nb is 1 to 50 mass %, and an average particle diameter of primary particles is 30 to 200 nm, preferably, a CV value per unit mass of the powder (μF.Math.V/g) is 250 kμF.Math.V/g or more, or further, a CV value per unit volume (μF.Math.V/mm.sup.3) in terms of a molded body whose molding density ρ (g/cm.sup.3) is ρ.sub.c (g/cm.sup.3)=−0.012R.sub.Nb+3.57, wherein R.sub.Nb: Nb content (mass %) in an alloy, is 900 μF.Math.V/mm.sup.3 or more, and an anode element for a solid electrolytic capacitor using the alloy powder.

A Ta-Nb alloy powder which has provides a capacitor having a higher capacitance than a Ta capacitor and a better thermal stability in terms of an oxide film is better than a Nb capacitor, the Ta-Nb alloy powder being a Ta-Nb alloy powder produced by a thermal CVD method, wherein a content of Nb is 1 to 50 mass %, and an average particle diameter of primary particles is 30 to 200 nm, preferably, a CV value per unit mass of the powder (μF.Math.V/g) is 250 kμF.Math.V/g or more, or further, a CV value per unit volume (μF.Math.V/mm.sup.3) in terms of a molded body whose molding density ρ (g/cm.sup.3) is ρ.sub.c (g/cm.sup.3)=−0.012R.sub.Nb+3.57, wherein R.sub.Nb: Nb content (mass %) in an alloy, is 900 μF.Math.V/mm.sup.3 or more, and an anode element for a solid electrolytic capacitor using the alloy powder.

The present invention relates to a composite tantalum powder and a process for preparing the same, and to a capacitor anode prepared from the tantalum powder. The method for preparing a composite tantalum powder comprises the following steps of: 1) providing a tantalum powder prepared by a reduction process, and flattening the tantalum powder so as to prepare a flaked tantalum powder; 2) providing a granular tantalum powder prepared from tantalum ingot; 3) mixing the flaked tantalum powder and the granular tantalum powder to give a tantalum powder mixture; and 4) thermally treating the tantalum powder mixture, and then pulverizing, screening to give a composite tantalum powder. The present invention further relates to a composite tantalum powder prepared from the process and the use thereof in a capacitor.

The present invention relates to a composite tantalum powder and a process for preparing the same, and to a capacitor anode prepared from the tantalum powder. The method for preparing a composite tantalum powder comprises the following steps of: 1) providing a tantalum powder prepared by a reduction process, and flattening the tantalum powder so as to prepare a flaked tantalum powder; 2) providing a granular tantalum powder prepared from tantalum ingot; 3) mixing the flaked tantalum powder and the granular tantalum powder to give a tantalum powder mixture; and 4) thermally treating the tantalum powder mixture, and then pulverizing, screening to give a composite tantalum powder. The present invention further relates to a composite tantalum powder prepared from the process and the use thereof in a capacitor.

This invention relates to a preparation method of rare earth oxide dispersion strengthened fee grain tungsten materials, the mass percent of the rare earth oxide is of 0.1-2%, and the rest ingredient is W. Weigh soluble rare earth salt and tungstate, dissolve into water to made into 50-100 g/L of rare earth salt solution and 150-300 g/L of tungstate solution, respectively. Firstly, add trace alkali in rare earth salt solution to control pH in 7-8, then add organic dispersant and stir to form evenly suspended R(OH).sub.3 particle colloid (R refers to rare earth element). Secondly pour the tungstate solution into the R(OH).sub.3colloid, add trace acid to control pH in 6-7, then add organic dispersant and stir to form tungstic acid micro particles, which wrap around the colloidal particles, forming coprecipitation coating particle colloid. Thirdly, the coprecipitation coating particle colloidal is spray-dried, forming tungsten and rare earth oxide compound precursor powder. Alter that, ultrafine or nanoscale tungsten powder with particle size of 50˜500 nm is obtained through a process of calcination subsequent with hydrogen thermal reduction. Finally, the tungsten powder is subjected to ordinary compression molding and then conventional high temperature sintering. The trace rare earth oxide dispersion strengthened high performance fine grain tungsten materials prepared by this invention, its density is close to full density (98.5% or higher), its grain size is uniform and very fine (average in 5˜10 microns), and the rare earth oxides particles evenly distribute in tungsten intracrystalline or grain, boundary with particle size of 100˜500 nm.

This invention relates to a preparation method of rare earth oxide dispersion strengthened fee grain tungsten materials, the mass percent of the rare earth oxide is of 0.1-2%, and the rest ingredient is W. Weigh soluble rare earth salt and tungstate, dissolve into water to made into 50-100 g/L of rare earth salt solution and 150-300 g/L of tungstate solution, respectively. Firstly, add trace alkali in rare earth salt solution to control pH in 7-8, then add organic dispersant and stir to form evenly suspended R(OH).sub.3 particle colloid (R refers to rare earth element). Secondly pour the tungstate solution into the R(OH).sub.3colloid, add trace acid to control pH in 6-7, then add organic dispersant and stir to form tungstic acid micro particles, which wrap around the colloidal particles, forming coprecipitation coating particle colloid. Thirdly, the coprecipitation coating particle colloidal is spray-dried, forming tungsten and rare earth oxide compound precursor powder. Alter that, ultrafine or nanoscale tungsten powder with particle size of 50˜500 nm is obtained through a process of calcination subsequent with hydrogen thermal reduction. Finally, the tungsten powder is subjected to ordinary compression molding and then conventional high temperature sintering. The trace rare earth oxide dispersion strengthened high performance fine grain tungsten materials prepared by this invention, its density is close to full density (98.5% or higher), its grain size is uniform and very fine (average in 5˜10 microns), and the rare earth oxides particles evenly distribute in tungsten intracrystalline or grain, boundary with particle size of 100˜500 nm.