MATERIAL INTERFACES FOR MAGNETOHYDRODYNAMIC METAL MANUFACTURING

• US 20170252822A1
• 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, Fontana, Richard Remo
• Granted Patent: US 10,195,665 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 a combination of materials suitable for withstanding prolonged exposure to high temperatures associated with certain liquid metals while facilitating efficient delivery of current to produce magnetohydrodynamic forces controllable over a range of frequencies associated with commercially viable three-dimensional fabrication.

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;

one or more magnets supported on 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 electric current is conductible from the electrodes into the firing chamber in a direction intersecting the magnetic field in the firing chamber, and a portion of the housing defining the discharge region of the fluid chamber is formed of a ceramic material.

2. The nozzle of claim 1, wherein the ceramic material includes one or more of alumina, sapphire, ruby, aluminum nitride, aluminum carbide, silicon nitride, sialons, and boron carbide.

3. The nozzle of claim 1, wherein a portion of the housing defining at least a portion of the fluid chamber away from the discharge region is formed of a metal.

4. The nozzle of claim 1, wherein a portion of the housing defining the at least one portion of the fluid chamber away from the discharge region is formed of a ceramic material.

5. The nozzle of claim 1, wherein the electrodes defining the at least one portion of the firing chamber are formed of a metal.

6. The nozzle of claim 1, wherein at least one of the electrodes is integrally formed with a portion of the housing defining at least one portion of the fluid chamber away from the discharge region such that the at least one electrode and the portion of the housing defining the at least one portion of fluid chamber away from the discharge region are formed of the same material.

7. The nozzle of claim 1, wherein the firing chamber is substantially adjacent to a discharge orifice of the discharge region.

8. The nozzle of claim 1, wherein a volume of the firing chamber is greater than about 50 percent of a total volume of the fluid chamber.

9. The nozzle of claim 1, wherein the electrodes include a lining disposed along at least a portion of the fluid chamber between the inlet region and the discharge region.

10. The nozzle of claim 9, wherein the lining is plated on the material of the housing defining the fluid chamber.

11. The nozzle of claim 9, wherein a material of the housing on which the lining is disposed includes one or more of titanium nitride, titanium aluminum nitride, titanium carbide, alumina, titanium and carbonitride.

12. The nozzle of claim 1, further comprising at least one heater in thermal communication with the firing chamber.

13. The nozzle of claim 12, wherein the heater includes an induction coil disposed about at least a portion of the firing chamber.

14. The nozzle of claim 1, wherein the electrodes are formed of a first material and the housing is formed of a second material, the second material having a higher melting temperature than the first material.

15. The nozzle of claim 1, wherein the electrodes are formed of tantalum, niobium, or a combination thereof.

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

providing a liquid metal in a fluid chamber having an inlet region and a discharge region, the fluid chamber at least partially defined by a housing, the fluid chamber;

directing a magnetic field through the housing;

moving the discharge region in a controlled pattern; and

based on the position of the discharge region along the controlled pattern, conducting electric current through electrodes defining at least one portion of a firing chamber within the fluid chamber between the inlet region and the discharge region, wherein the electrodes defining the at least one portion of the firing chamber have an electrical resistivity substantially equal to the resistivity of the liquid metal moving through the firing chamber, and a portion of the housing defining the discharge region has an electrical resistivity substantially greater than the resistivity of the liquid metal moving through the discharge region, and electric current conducted through the electrodes is conducted into the liquid metal along a direction intersecting the magnetic field in the firing chamber to eject at least a portion of the liquid metal from the discharge region.