Method for manufacturing metal powder

• US 7,066,980 B2
• Filed: 09/08/2003
• Issued: 06/27/2006
• Est. Priority Date: 09/10/2002
• Status: Active Grant

• Current Assignee: Shoei Chemical Inc.
• Original Assignee: Shoei Chemical Inc.
• Inventors: Akimoto, Yuji, Nagashima, Kazuro, Ieda, Hidenori, Maekawa, Masayuki, Ono, Shinichi
• Primary Examiner(s): WYSZOMIERSKI, GEORGE P
• Application Number:
  US10/657,569
• Publication Number:
  US 20040055418A1
• Time in Patent Office: 1,023 Days
• Field of Search: 753/51, 753/69, 753/71
• US Class Current: 75/351
• CPC Class Codes: B22F 1/07 Metallic powder characterised by particles having a nanoscale microstructure nanosized particles B22F1/054
• CPC Class Codes: B22F 9/30 with decomposition of metal compounds, e.g. by pyrolysis
• CPC Class Codes: H01B 1/22 the conductive material comprising metals or alloys
• CPC Class Codes: H05K 1/092 Dispersed materials, e.g. conductive pastes or inks

Abstract

A method in which a metal powder is produced by ejecting a thermally decomposable metal compound powder into a reaction vessel through a nozzle together with a carrier gas under the condition V/S>600, where V is the flow rate of the carrier gas per unit time (liter/min), and S is the cross-sectional area of the nozzle opening part (cm²), and heating this metal powder at a temperature which is higher than the decomposition temperature of the metal compound powder and not lower than (Tm−200)° C., where Tm is the melting point of the metal, in a state where the metal compound powder is dispersed in the gas phase at a concentration of 10 g/liter or less. The method provides a fine, spherical, highly-crystallized metal powder which has a high purity, high density, high dispersibility and extremely uniform particle size, at low cost and using a simple process.

Claims

1. A method for manufacturing a highly-crystallized metal powder, comprising:

ejecting a raw material powder comprising one or more kinds of thermally decomposable metal compounds into a reaction vessel through a nozzle together with a carrier gas under the condition V/S>

600 where V is the flow rate of the carrier gas per unit time (liter/min) and S is the cross-sectional area of the nozzle opening part (cm²); and

producing the metal powder by heating the raw material powder at a temperature which is higher than the decomposition temperature of the raw material powder and not lower than (Tm−

200)°

C. where Tm (°

C.) is the melting point of the metal, in a state where the raw material powder is dispersed in the gas phase at a concentration of 10 g/liter or less.

2. The method according to claim 1, wherein the raw material powder is mixed and dispersed in the carrier gas using a dispersing apparatus prior to being ejected into the reaction vessel through the nozzle.

3. The method according to claim 1, wherein the particle size of the raw material powder has been adjusted beforehand.

4. The method according to claim 1, wherein the raw material powder is a composite powder of metal compounds containing two or more metal elements, and the metal powder is an alloy powder.

5. The method according to claim 1, wherein the metal powder has a mean particle size of from approximately 0.1 μ

m to 20 μ

m.

6. The method according to claim 1, wherein the raw material powder is dispersed in the gas phase at a concentration of at least 0.01 g/liter.

7. The method according to claim 1, wherein the metal is selected from the group consisting of copper, nickel, cobalt, iron, silver, palladium, gold, platinum and alloys thereof.

8. A method for manufacturing a highly-crystallized metal powder comprising:

preparing a raw material powder containing two or more metal elements, which are constituents of an alloy powder to be produced, at a substantially constant compositional ratio in individual particles of the raw material powder;

collecting the raw material powder;

dispersing the collected raw material powder in a carrier gas;

ejecting the carrier gas having the raw material powder dispersed therein into a reaction vessel through a nozzle under the condition V/S>

600, where V is the flow rate of the carrier gas per unit time (liter/min) and S is the cross-sectional area of the nozzle opening part (cm²); and

producing the metal powder in the form of the alloy powder by heating the raw material powder at a temperature which is higher than the decomposition temperature of the raw material powder and not lower than (Tm−

200)°

C. where Tm (°

C.) is the melting point of the alloy to be produced, in a state where the raw material powder is dispersed in the gas phase in the reaction vessel at a concentration of 10 g/liter or less.