Hydrometallurgical process for producing spherical maraging steel powders with readily oxidizable alloying elements

• US 4,859,237 A
• Filed: 01/04/1988
• Issued: 08/22/1989
• Est. Priority Date: 01/04/1988
• Status: Expired due to Fees

• Current Assignee: GTE Products Corporation
• Original Assignee: GTE Products Corporation
• Inventors: Johnson, Walter A., Kopatz, Nelson E., Ritsko, Joseph E.
• Primary Examiner(s): Stoll, Robert L.
• Application Number:
  US07/140,701
• Time in Patent Office: 596 Days
• Field of Search: 75/0.5 AA, 75/0.5 A, 75/0.5 BB, 75/0.5 AB, 75/0.5 BA, 75/10.22, 75/10.63, 420/590, 502/8
• US Class Current: 75/342
• CPC Class Codes: B22F 1/065 Spherical particles
• CPC Class Codes: C22C 33/0207 Using a mixture of prealloyed powders or a master alloy mixtures of metal powder in general B22F1/09

Abstract

A process for producing a blend of maraging steel alloys and an oxidizable metal comprises forming an aqueous solution or iron, cobalt, nickel and molybdenum in a predetermined ratio. Thereafter, a reducible solid material containing the metals is produced from the solution. The solid material is reduced to metallic powder particles which are entrained in a carrier gas and fed into a high temperature zone to form droplets which are cooled to form essentially spherical shaped metal alloy particles. These particles are combined with a predetermined amount of at least one easily oxidizable metal selected from the group consisting of aluminum, titanium and vanadium to form a relative uniform blend of the spherical shaped particles and the readily oxidizable metal.

Claims

1. A process comprising:

(a) forming an aqueous solution containing the metal values of iron, cobalt, nickel and molybdenum, said metals being present in a predetermined ration to form a maraging steel alloy,

(b) forming from said solution a reducible solid material selected from the group consisting of salts of said metals, oxides of said metals, hydroxides of said metals and mixtures thereof,

(c) heating said solid in a reducing atmosphere at a temperature above the reduction temperature but below the melting point of the metals in the solids thereby reducing said solid material to form metallic powder particles,

(d) entraining at least a portion of said powder particles in a carrier gas,

(e) feeding said entrained particles and said carrier gas into a high temperature zones and maintaining said particles in said zone for a sufficient time to melt at least about 50% by weight of said particles, and to form droplets therefrom, and

(f) cooling said droplets to form essentially spherical shaped alloy particles and

(g) combining said spherical shaped particles with a predetermined amount of at least one readily oxidizable metal selected from the group consisting of aluminium, titanium and vanadium to form a relatively uniform blend of the spherical shaped particles and the readily oxidizable metal, said metals in said blend being a suitable ratio for producing a maraging steel alloy containing a readily oxidizable metal.

2. A process according to claim 1 wherein said solution contains a mineral acid selected from the group consisting of hydrochloric, sulfuric and nitric acids.

3. A process according to claim 2 wherein said mineral acid is hydrochloric acid.

4. A process according to claim 1 wherein said aqueous solution contains a water soluble acid.

5. A process according to claim 2 wherein said reducible solid material is formed by evaporation of the water from the solution.

6. A process according to claim 2 wherein said reducible solid material is formed by adjusting the pH of the solution to form a solid which is separated from the resulting aqueous phase.

7. A process according to claim 1 wherein said combining is achieved by blending.

8. A process according to claim 1 wherein said combining is achieved by agglomerating.

9. A process according to claim 8 wherein said agglomerating is achieved by spray drying.

10. A process according to claim 1 wherein said material produced by step (b) is subjected to a particle size reduction step prior to the reduction step (c).

11. A process according to claim 1 wherein the powder particles from step (c) are subjected to a particle size reduction step prior to the combining step (d).

12. A process according to claim 1 wherein at least 50% of said metallic alloy particles have a size less than about 20 micrometers.

13. A process according to claim 1 wherein said carrier gas is an inert gas.

14. A process according to claim 1 wherein said high temperature zone is created by a plasma torch.

15. A process according to claim 1, from step (e) wherein essentially all of said metal particles are melted.