Sintering additively manufactured parts in microwave oven

Patent metadata

Field	Value
Publication number	US-2019030601-A1
Application number	US-201815961372-A
Country	US
Kind code	A1
Filing date	Apr 24, 2018
Priority date	Dec 2, 2016
Publication date	Jan 31, 2019
Grant date	—

Abstract

A method comprising supplying a first material containing a removable binder and greater than 50% volume fraction of a powdered metal having a melting point greater than 1200 degrees C., in which more than 50% of powder particles of the powdered metal have a diameter less than 10 microns, additively depositing the first material in successive layers to form a green body, removing the binder to form a brown body, loading the brown part into a fused tube formed from a second material having an operating temperature less than substantially 1200 degrees C., a thermal expansion coefficient lower than 1×10-6/° C., and a microwave field penetration depth of 10 m or higher, sealing the fused tube and replacing internal air with a sintering atmosphere, applying microwave energy from outside the sealed fused tube to the brown part, and sintering the brown part at a temperature lower than 1200 degrees C.

First claim

What is claimed is:

1 . A method for additive manufacturing, the method comprising:
supplying a first material containing a removable binder and greater than 50% volume fraction of a powdered metal having a melting point greater than 1200 degrees C., in which more than 50% of powder particles of the powdered metal have a diameter less than 10 microns; additively depositing the first material in successive layers to form a green body; removing the binder to form a brown body; loading the brown part into a fused tube formed from a second material having an operating temperature less than substantially 1200 degrees C., a thermal expansion coefficient lower than 1×10-6/° C., and a microwave field penetration depth of 10 m or higher; sealing the fused tube and replacing internal air with a sintering atmosphere; applying microwave energy from outside the sealed fused tube to the brown part; and sintering the brown part at a temperature lower than 1200 degrees C.

2 . The method according to claim 1 , in which supplying the first material comprises supplying the first material in which more than 90 percent of the powder particles of the powdered metal have a diameter less than 8 microns.

3 . The method according to claim 1 , further comprising:
applying microwave energy from outside the sealed fused tube to susceptor members, of susceptor material, arranged outside the sealed fused tube.

4 . The method according to claim 3 , in which the susceptor material is one of SiC or MoSi2.

5 . The method according to claim 1 , further comprising:
resistively heating susceptor members, of susceptor material, arranged outside the sealed fused tube.

6 . The method according to claim 5 , in which the susceptor material is one of SiC or MoSi2.

7 . The method according to claim 1 , further comprising:
ramping a temperature inside the fused tube at greater than 10 degrees C. per minute but less than 40 degrees C. per minute.

8 . The method according to claim 1 , in which the second material of the fused tube is amorphous fused silica.

9 . The method according to claim 1 , in which the sintering atmosphere comprises at least 3% Hydrogen.

10 . The method according to claim 1 , in which the powdered metal is a stainless steel.

11 . The method according to claim 1 , in which the powdered metal is a tool steel.

12 . A method for additive manufacturing, the method comprising:
supplying a first material containing a removable binder and greater than 50% volume of a powdered metal having a melting point greater than 1200 degrees C., in which more than 50% of powder particles of the powdered metal have a diameter less than 10 microns; additively depositing the first material with a nozzle having an internal diameter smaller than 300 microns; removing the binder to form a brown body; loading the brown part into a fused tube formed from a second material having a thermal expansion coefficient lower than 1×10-6/° C.; sealing the fused tube and replacing internal air with a sintering atmosphere; applying radiant energy from outside the sealed fused tube to the brown part; and sintering the brown part at a temperature higher than 500 degrees C. but less than 1200 degrees C.

13 . The method according to claim 12 , wherein additively depositing the first material comprises additively depositing the first material at a layer height substantially ⅔ or more of a nozzle width.

14 . The method according to claim 12 , wherein supplying the first material comprises supplying the first material in which more than 90 percent of the powder particles of the powdered metal have a diameter less than 8 microns.

15 . The method according to claim 12 , further comprising:
applying microwave energy from outside the sealed fused tube to the brown part.

16 . The method according to claim 15 , further comprising:
applying microwave energy from outside the sealed fused tube to susceptor members, of susceptor material, arranged outside the sealed fused tube.

17 . The method according to claim 16 , in which the susceptor material is one of SiC or MoSi2.

18 . The method according to claim 12 , further comprising:
resistively heating susceptor members, of susceptor material, arranged outside the sealed fused tube.

19 . The method according to claim 18 , in which the susceptor material is one of SiC or MoSi2.

20 . The method according to claim 12 , further comprising:
ramping a temperature inside the fused tube at greater than 10 degrees C. per minute but less than 40 degrees C. per minute.

21 . The method according to claim 12 , in which the second material of the fused tube is amorphous fused silica.

22 . The method according to claim 12 , in which the powdered metal is a stainless steel.

Assignees

• Markforged Inc

Inventors

• Mark Gregory Thomas

Classifications

• B22F10/40

  Structures for supporting workpieces or articles during manufacture and removed afterwards · CPC title

• B22F3/1025 Primary

  not by heating only · CPC title

• B22F1/142

  Thermal or thermo-mechanical treatment · CPC title

• B22F10/16

  by embedding the binder within the powder bed · CPC title

• B22F1/10

  Metallic powder containing lubricating or binding agents; Metallic powder containing organic material · CPC title