PRODUCTION OF SUBSTANTIALLY SPHERICAL METAL POWDERS

• US 20170021425A1
• Filed: 08/11/2016
• Published: 01/26/2017
• Est. Priority Date: 05/13/2014
• Status: Active Grant

• Current Assignee: University of Utah Research
• Original Assignee: University of Utah Research Foundation (State of Utah)
• Inventors: Fang, Zhigang Z., Xia, Yang, Sun, Pei, Zhang, Ying
• Granted Patent: US 10,130,994 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B22F 1/05 Metallic powder characterised by the size or surface area of the particles
• CPC Class Codes: B22F 1/065 Spherical particles
• CPC Class Codes: B22F 1/09 Mixtures of metallic powders
• CPC Class Codes: B22F 1/10 Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
• CPC Class Codes: B22F 1/107 containing organic material comprising solvents, e.g. for slip casting
• CPC Class Codes: B22F 1/12 Metallic powder containing non-metallic particles containing lubricating or binding agents or organic material B22F1/10
• CPC Class Codes: B22F 1/148 Agglomerating
• CPC Class Codes: B22F 10/28 Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/32 of the atmosphere, e.g. composition or pressure in a building chamber
• CPC Class Codes: B22F 10/64 by thermal means control of energy beam parameters for post heating B22F10/364
• CPC Class Codes: B22F 10/73 of powder
• CPC Class Codes: B22F 2003/244 Leaching
• CPC Class Codes: B22F 2009/001 from scrap particles
• CPC Class Codes: B22F 2009/043 by ball milling
• CPC Class Codes: B22F 2201/11 Argon
• CPC Class Codes: B22F 2301/052 Aluminium
• CPC Class Codes: B22F 2301/15 Nickel or cobalt
• CPC Class Codes: B22F 2301/20 Refractory metals
• CPC Class Codes: B22F 2301/205 Titanium, zirconium or hafnium
• CPC Class Codes: B22F 2301/35 Iron
• CPC Class Codes: B22F 2302/45 : Others, including non-metals
• CPC Class Codes: B22F 2304/10 : Micron size particles, i.e. above 1 micrometer up to 500 micrometer
• CPC Class Codes: B22F 2304/15 : Millimeter size particles, i.e. above 500 micrometer
• CPC Class Codes: B22F 2998/10 : Processes characterised by the sequence of their steps
• CPC Class Codes: B22F 2999/00 : Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/04 : by applying fluid pressure , e.g. by cold isostatic pressing [CIP]
• CPC Class Codes: B22F 3/1021 : Removal of binder or filler removal of binder from ceramics C04B35/638
• CPC Class Codes: B22F 3/1025 : not by heating only
• CPC Class Codes: B22F 3/15 : Hot isostatic pressing
• CPC Class Codes: B22F 3/16 : in successive or repeated steps
• CPC Class Codes: B22F 3/225 : by injection molding
• CPC Class Codes: B22F 3/24 : After-treatment of workpieces or articles B22F3/1146 takes precedence
• CPC Class Codes: B22F 9/026 : Spray drying of solutions or suspensions
• CPC Class Codes: B22F 9/04 : starting from solid material, e.g. by crushing, grinding or milling C22C1/1084 takes precedence; crushing, grinding or milling, in general, see the relevant subclasses, e.g. B02C
• CPC Class Codes: C01B 6/02 : Hydrides of transition elements; Addition complexes thereof
• CPC Class Codes: C22C 1/06 : with the use of special agents for refining or deoxidising
• CPC Class Codes: Y02P 10/20 : Recycling
• CPC Class Codes: Y02P 10/25 : Process efficiency

Abstract

A method for producing a substantially spherical metal powder is described. A particulate source metal includes a primary particulate and has an average starting particle size. The particulate source metal is optionally ball milled and mixed with a binder in a solvent to form a slurry. The slurry is granulated to form substantially spherical granules, wherein each granule comprises an agglomeration of particulate source metal in the binder. The granules are debinded at a debinding temperature to remove the binder from the granules forming debinded granules. The debinded granules are at least partially sintered at a sintering temperature such that particles within each granule fuse together to form partially or fully sintered solid granules. The granules can then be optionally recovered to form a substantially spherical metal powder.

Claims

1. A method for producing a substantially spherical metal or metal alloy powder comprising:

providing a particulate source metal including a primary particulate and having an average starting particle size;

mixing the particulate source metal with a binder and an optional solvent to form a slurry;

granulating the slurry to form substantially spherical granules, wherein each granule comprises an agglomeration of particulate source metal;

debinding the granules at a debinding temperature to reduce a binder content of the granules forming debinded granules;

at least partially sintering the debinded granules at a sintering temperature such that particles within each granule fuse together to form partially or fully sintered granules;

recovering the sintered granules to form the substantially spherical metal or metal alloy powder.

2. The method of claim 1, wherein the substantially spherical metal powder has an average final particle size from about 1 to about 1000 micrometers.

3. The method of claim 1, wherein the substantially spherical metal powder is selected from the group consisting of titanium, zirconium, hafnium, thorium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, nickel, aluminum, iron, alloys of the above metals with each other, alloys of the above metals with other metals, alloys of the above metals with non-metals, CP—

Ti alloy, Ti-6Al-4V alloy, nickel-based high temperature alloys, stainless steel, and combinations thereof.

4. The method of claim 1, wherein the substantially spherical metal powder comprises the metal or metal alloy selected from the group consisting of nickel based super alloy, cobalt-chromium alloy, aluminum alloys, stainless steel alloys, tantalum alloys, tungsten alloys, molybdenum alloys, and combinations thereof.

5. The method of claim 1, wherein the substantially spherical metal powder has an average particle aspect ratio less than about 1.5.

6. The method of claim 1, wherein the particulate source metal comprises titanium, titanium hydride, Al—

V master alloy, titanium oxide, or mixtures thereof.

7. The method of claim 1, wherein the particulate source metal comprises zirconium, hafnium, thorium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, nickel, aluminum, iron, alloys of the above metals with each other, alloys of the above metals with metals, alloys of the above metals with non-metals, CP—

Ti alloy, Ti-6Al-4V alloy, nickel-based high temperature alloys, stainless steel, hydrides thereof, oxides thereof, mixtures thereof, or combinations thereof.

8. The method of claim 1, wherein the particulate source metal consists essentially of one or more of a metal or a metal alloy.

9. The method of claim 1, further comprising making the particulate source metal from a raw material selected from titanium slag, upgraded titanium slag, titanium dioxide, scrap titanium, scrap titanium alloy, or a combination thereof.

10. The method of claim 1, wherein the average starting particle size of the primary particulate is from 0.1 to 100 micrometers.

11. The method of claim 1, wherein mixing the particulate source metal with a binder further comprises wet ball milling the particulate source metal and the binder in the solvent.

12. The method of claim 1, wherein granulating the slurry comprises spray drying, rotary drying, vibratory pelletizing, freeze granulation and drying, or combinations thereof

13. The method of claim 1, wherein the granules have an average granule size from about 20% to about 50% larger than an average final particle size of the substantially spherical metal powder.

14. The method of claim 1, wherein the granules have an average granule size greater than 10 micrometers.

15. The method of claim 1, wherein the debinded granules are mixed with CaO powder such that granules are separated by CaO powder during sintering.

16. The method of claim 1, wherein sintering the debinded granules is performed until each sintered granule reaches a relative density greater than 65%.

17. The method of claim 1, wherein sintering the debinded granules is performed such that each sintered granule is substantially free from bonding to each other.

18. The method of claim 1, wherein sintering the debinded granules is performed until the debinded granules fuse together at contact points between the debinded granules but the debinded granules retain at least about 20% unfused surface area on average.

19. The method of claim 1, wherein the at least partially sintering is performed such that the granules are connected to each other forming a frangible body of at least partially sintered granules;

and wherein separating is accomplished by breaking the frangible body to recover the substantially spherical metal powder.

20. The method of claim 18, wherein breaking the frangible body comprises ball milling the frangible body.