Metallic parts fabrication using selective inhibition of sintering (SIS)

• US 20040018107A1
• Filed: 06/30/2003
• Published: 01/29/2004
• Est. Priority Date: 07/23/2002
• Status: Active Grant

• Current Assignee: University of Southern California
• Original Assignee: University of Southern California
• Inventors: Khoshnevis, Behrokh
• Granted Patent: US 7,241,415 B2
• Time in Patent Office: Days
• US Class Current: 419/6
• CPC Class Codes: B22F 10/28 Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/60 Treatment of workpieces or articles after build-up
• CPC Class Codes: B22F 12/53 Nozzles
• CPC Class Codes: B22F 2003/1046 with separating means for articles to be sintered
• 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 3/004 Filling molds with powder feeding material to presses in general B30B15/302
• CPC Class Codes: B22F 3/02 Compacting only
• CPC Class Codes: B30B 15/302 Feeding material in particulate or plastic state to moulding presses
• 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 70/00 Materials specially adapted for additive manufacturing
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing
• CPC Class Codes: Y02P 10/25 Process efficiency

Abstract

A selective inhibition of sintering (SIS) technique may be used to fabricate a three-dimensional (3-D) dense metal object from a binderless metal powder. A number of layers of metal powder are provided on a build tank. For each layer, regions of the layer are sinter-inhibited, e.g., by depositing a sinter-inhibiting material such as a ceramic slurry, a metal salt, or oxidizing metal particles in the powder using chemicals or a concentrated heat source. Each layer may be compacted before the next layer is provided. A final compact may then be sintered. Unwanted sintered sections may be removed from the compact at boundaries formed by the sinter-inhibited (unsintered) regions, and the object extracted.

Claims

1. A method comprising:

providing a layer of a metal powder;

sinter-inhibiting one or more regions in the layer;

repeating said providing and sinter-inhibiting for a plurality of layers;

compacting the plurality of layers to form a compact;

sintering the compact; and

removing one or more sintered sections at a boundary formed by the sinter-inhibited regions in the compact.

2. The method of claim 1, wherein said removing comprises extracting a three-dimensional (3-D) metal object from the compact.

3. The method of claim 1, wherein said compacting comprises compacting each layer before another layer is provided on said layer.

4. The method of claim 3, further comprising:

compacting each layer after sinter-inhibiting one or more regions in the layer.

5. The method of claim 3, further comprising:

compacting each layer before sinter-inhibiting one or more regions in the layer.

6. The method of claim 3, wherein said compaction comprises pressing the layer with a press surface, and further comprising:

cleaning the press surface between each successive layer.

7. The method of claim 1, wherein said sinter-inhibiting comprises depositing a sinter-inhibiting material on the one or more regions of the layer.

8. The method of claim 7, wherein said depositing comprises extruding the sinter-inhibiting material through a nozzle.

9. The method of claim 7, wherein said depositing comprises printing the sinter-inhibiting material with a printer head.

10. The method of claim 7, wherein the sinter-inhibiting material comprises a solution that when dried results in crystals or other solid forms with a high sintering temperature.

11. The method of claim 7, wherein the sinter-inhibiting material comprises a metal salt.

12. The method of claim 11, wherein the metal salt comprises potassium phosphate (K₃PO₄).

13. The method of claim 7, wherein the sinter-inhibiting material comprises a ceramic slurry.

14. The method of claim 1, wherein said sinter-inhibiting comprises oxidizing metal powder particles in the one or more regions.

15. The method of claim 14, wherein said oxidizing comprises heating said metal power particles in the presence of oxygen.

16. The method of claim 15, wherein said oxidizing comprises scanning a laser over the one or more regions.

17. The method of claim 15, wherein said oxidizing comprises moving a micro-torch over the one or more regions.

18. The method of claim 1, wherein the metal powder comprises a binderless powder.

19. The method of claim 1, wherein said compacting comprises cold welding metal powder particles in the plurality of layers.

20. The method of claim 1, further comprising:

creating a boundary in said plurality of layers to form a block.

21. The method of claim 20, wherein said creating the boundary comprises depositing an adhesive at a periphery of each layer.

22. A system comprising:

means for spreading a plurality of layers of a metal powder;

a press to compress said layers;

means for sinter-inhibiting one or more regions in a plurality of said layers; and

a furnace to sinter the metal powder in a compact formed from said plurality of layers.

23. The system of claim 22, wherein the means for spreading comprises a roller.

24. The system of claim 22, wherein the means for spreading comprises a blade.

25. The system of claim 22, wherein the means for sinter-inhibiting comprises means for depositing a sinter-inhibiting material over said one or more regions.

26. The system of claim 25, wherein the means for depositing comprises a nozzle to extrude the sinter-inhibiting material.

27. The system of claim 25, wherein the means for depositing comprises a printer head to print the sinter-inhibiting material.

28. The system of claim 25, wherein the sinter-inhibiting material comprises a metal salt.

29. The system of claim 28, wherein the metal salt comprises potassium phosphate (K₃PO₄).

30. The system of claim 25, wherein the sinter-inhibiting material comprises a ceramic slurry.

31. The system of claim 22, wherein the means for sinter-inhibiting comprises a scannable laser operative to oxidize metal powder particles in said one or more regions.

32. The system of claim 22, wherein the means for sinter-inhibiting comprises a controllable micro-torch operative to oxidize metal powder particles in said one or more regions.

33. The system of claim 22, wherein the metal powder comprises a binderless metal powder.

34. The system of claim 22, further comprising:

means for cleaning a surface of the press before compacting each successive layer.

35. The system of claim 22, further comprising:

a heater to heat each of said plurality of layers.

36. The system of claim 35, wherein said heater comprises an array of gas torches operative to be selectively turned on or off.

37. The system of claim 35, wherein said heater comprises a an array of very high temperature electric filaments operative to be selectively turned on or off by electric current or by a shutter.

38. A method comprising:

providing a layer of a metal powder;

sinter-inhibiting one or more regions in the layer;

compacting the layer;

sintering metal powder in the layer;

repeating said providing, sinter-inhibiting, compacting, and sintering for a plurality of layers; and

removing one or more sintered sections at a boundary formed by the sinter-inhibited regions in the compact.

39. The method of claim 38, wherein said removing comprises extracting a three-dimensional (3-D) metal object from the compact.

40. The method of claim 38, wherein the compaction of the layer is performed prior to the sinter-inhibiting.