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US 5,294,242 AGranted
Method for making metal powders
AssigneeAir Products and Chemicals, Inc.
InventorsZbigniew Zurecki, Kerry B. Berger, Robert B. Swan
Life of this patent
Estimating the term…
Abstract
A metal powder is produced by atomizing molten metal in an electric arc spray gun and rapidly quenching the resulting droplets in a liquid cryogen to form fine, highly spherical, oxide-free particles. The rapid quenching yields particles with a very fine, uniform microstructure which melt rapidly and uniformly when later heated. The powder is especially well-suited for making solder paste for device fabrication in the electronics industry.
Claims18
A method for producing metal-containing powder comprising:
- (a) forming an electric arc between two metal-containing wires in an electric arc spray gun, thereby causing said wires to melt;
- (b) directing pressurized inert gas across said arc to form molten droplets which are discharged with said inert gas from said gun;
- (c) contacting said molten droplets and inert gas discharged from said gun with a liquid cryogen, thereby solidifying said molten droplets to form solid particles having an average particle size between 1 and 120 microns, cooling said inert gas, vaporizing at least a portion of said liquid cryogen, and forming a mixture of cryogen, cooled inert gas, and said solid particles;
- (d) separating said solid particles from said mixture to yield said metal-containing powder.
1 more element
A method for producing metal-containing powder comprising:
- (a) forming an electric arc between two metal-containing wires in an electric arc spray gun, thereby causing said wires to melt;
- (b) directing pressurized inert gas across said arc to form molten droplets which are discharged with said inert gas from said gun;
- (c) passing said molten droplets and inert gas discharged from said gun into a vessel containing a liquid cryogen, thereby solidifying said molten droplets to form solid particles, cooling said inert gas, and vaporizing at least a portion of said liquid cryogen, and
- (d) withdrawing from said vessel a mixture of liquid cryogen and solid particles suspended therein, vaporizing the liquid cryogen in said mixture, and recovering said solid particles to yield said metal-containing powder.
1 more element
A method for producing metal-containing powder comprising:
- (a) forming an electric arc between two metal-containing wires in an electric arc spray gun, thereby causing said wires to melt;
- (b) directing pressurized inert gas across said arc to form molten droplets which are discharged with said inert gas from said gun;
- (c) passing said molten droplets and inert gas discharged from said gun into a first vessel containing a liquid cryogen, thereby solidifying said molten droplets to form solid particles, cooling said inert gas, vaporizing a portion of said liquid cryogen, and forming a mixture of liquid cryogen, vaporized cryogen, cooled inert gas, and said solid particles;
- (d) withdrawing from said first vessel a stream of liquid cryogen and solid particles suspended therein, vaporizing the liquid cryogen, and recovering said solid particles to yield a first fraction of said metal-containing powder;
- (e) withdrawing from said first vessel a mixture of cool inert gas, vaporized cryogen, entrained liquid cryogen, and entrained solid particles, and passing said mixture into a second vessel containing additional liquid cryogen wherein said entrained liquid cryogen and said entrained solid particles are separated from said vaporized cryogen and cool inert gas;
- (f) withdrawing from said second vessel a stream of vaporized cryogen and cool inert gas essentially free of entrained material;
- and
- (g) withdrawing from said second vessel a mixture of liquid cryogen and solid particles suspended therein, vaporizing the liquid cryogen in said mixture, and recovering said solid particles to yield a second fraction of said metal-containing powder.
5 more elements
Dependencies are inferred from the claim text.