CONTROLLING WETTING FOR MAGNETOHYDRODYNAMIC METAL MANUFACTURING

• US 20170252823A1
• Filed: 03/06/2017
• Published: 09/07/2017
• Est. Priority Date: 03/03/2016
• Status: Active Grant

• Current Assignee: Desktop Metal, Inc.
• Original Assignee: Desktop Metal, Inc.
• Inventors: Sachs, Emanuel Michael, Hoisington, Paul A.
• Granted Patent: US 10,906,102 B2
• Time in Patent Office: Days
• CPC Class Codes: B05B 5/025 Discharge apparatus, e.g. electrostatic spray guns
• CPC Class Codes: B22F 10/00 Additive manufacturing of workpieces or articles from metallic powder apparatus or devices therefor B22F12/00
• CPC Class Codes: B22F 10/22 Direct deposition of molten metal
• CPC Class Codes: B22F 10/32 of the atmosphere, e.g. composition or pressure in a building chamber
• CPC Class Codes: B22F 10/38 to achieve specific product aspects, e.g. surface smoothness, density, porosity or hollow structures
• CPC Class Codes: B22F 12/10 Auxiliary heating means
• CPC Class Codes: B22F 12/17 to heat the build chamber or platform
• CPC Class Codes: B22F 12/20 Cooling means
• CPC Class Codes: B22F 12/53 Nozzles
• CPC Class Codes: B22F 12/70 Gas flow means
• CPC Class Codes: B22F 12/90 Means for process control, e.g. cameras or sensors
• CPC Class Codes: B22F 2009/0892 casting nozzle; controlling metal stream in or after the casting nozzle
• CPC Class Codes: B22F 2202/06 Use of electric fields
• CPC Class Codes: B22F 2203/03 for feed-back
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/003 Apparatus, e.g. furnaces in general F27B
• CPC Class Codes: B22F 3/115 by spraying molten metal, i.e. spray sintering, spray casting
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: B33Y 50/02 for controlling or regulating additive manufacturing processes
• CPC Class Codes: B41J 2/14 : Structure thereof only for on-demand ink jet heads
• CPC Class Codes: B41J 2002/041 : Electromagnetic transducer
• CPC Class Codes: B41J 2202/04 : Heads using conductive ink
• CPC Class Codes: Y02P 10/25 : Process efficiency

Abstract

Devices, systems, and methods are directed to applying magnetohydrodynamic forces to liquid metal to eject liquid metal along a controlled pattern, such as a controlled three-dimensional pattern as part of additive manufacturing of an object. Nozzles associated with these devices, systems, and methods include one or more non-wetting surfaces in the vicinity of a discharge orifice of the nozzle. Such non-wetting surfaces can reduce the likelihood that wetting of the liquid metal in the vicinity of a discharge orifice of a nozzle will interfere with ejection of liquid metal droplets from the discharge orifice and, thus, can facilitate delivering droplets with accuracy suitable for commercially viable manufacturing using liquid metal to fabricate objects.

Claims

1. A nozzle for jetting liquid metal, the nozzle comprising:

a housing defining at least one portion of a fluid chamber, the fluid chamber having an inlet region and a discharge region, and the discharge region having a throat adjacent to a discharge orifice;

one or more magnets disposed relative to the housing with a magnetic field of the magnet directed through the housing; and

electrodes defining at least one portion of a firing chamber within the fluid chamber between the inlet region and the discharge region, wherein an outer surface of the housing adjacent to the discharge orifice includes a film that is substantially non-wetting with respect to a liquid metal stably supportable in the at least one portion of the firing chamber defined by the electrodes.

2. The nozzle of claim 1, wherein a contact angle between the film and liquid metal stably supportable in the firing chamber is greater than about 90 degrees.

3. The nozzle of claim 1, wherein a material of the housing defining the throat is wettable with respect to liquid metal stably supportable in the firing chamber.

4. The nozzle of claim 3, wherein liquid metal stably supportable in the firing chamber has a greater contact angle with the film than with material of the housing defining the throat.

5. The nozzle of claim 3, wherein the throat is substantially cylindrical, and a diameter of the throat is substantially equal to a diameter of the discharge orifice.

6. The nozzle of claim 1, wherein the film is integrally formed with the portion of the housing adjacent to the discharge orifice.

7. The nozzle of claim 1, wherein the film includes an oxide of a material forming the portion of the housing defining the throat.

8. The nozzle of claim 1, wherein the film includes one or more of tantalum oxide and chromium oxide.

9. The nozzle of claim 1, wherein the film is non-wetting with respect to one or more of aluminum, an aluminum alloy, and solder.

10. The nozzle of claim 1, wherein at least one of the electrodes is integrally formed with a portion of the housing adjacent to the at least one of the electrodes such that the at least one of the electrodes and the portion of the housing are formed of the same material.

11. The nozzle of claim 1, wherein the one or more magnets are arranged such that the magnetic field is directed through the firing chamber, and the electrodes are arranged such that electric current conducted from the electrodes into the firing chamber intersects the magnetic field in the firing chamber.

12. A method of additive manufacturing, the method comprising:

providing a liquid metal in a fluid chamber, the fluid chamber having an inlet orifice and a discharge orifice, and the fluid chamber having a throat adjacent to a discharge orifice, wherein the fluid chamber is at least partially defined by a housing;

directing a magnetic field through the housing; and

pulsing electric current into the liquid metal in a firing chamber within the fluid chamber, the pulsed electric current intersecting the magnetic field in the firing chamber to eject the liquid metal from the discharge orifice, wherein, during pulsations of electric current into the liquid metal, the throat is wetted by the liquid metal and an outer surface of the housing defining the discharge orifice is substantially non-wetted by the liquid metal.

13. The method of claim 12, wherein the outer surface of the housing defining the discharge orifice includes a film of an oxide of the material of the housing defining the throat.

14. The method of claim 13, wherein the film includes one or more of tantalum oxide and chromium oxide.

15. The method of claim 12, wherein a contact angle between the liquid metal and an outer surface of the housing defining the discharge orifice is greater than a contact angle between the liquid metal and material of the housing defining the throat.

16. The method of claim 15, wherein the contact angle between the liquid metal and the outer surface of the housing defining the discharge orifice is greater than about 90 degrees.

17. The method of claim 12, wherein the liquid metal includes one or more of aluminum, aluminum alloy, and solder.

18. The method of claim 12, wherein the pulsed electric current has a maximum frequency of less than about 10 kHz.

19. The method of claim 12, further comprising moving the housing in a controlled three-dimensional pattern relative to a build surface to form a three-dimensional object.