Fabricating an interface layer for removable support
View Patent ↗Support structures are used in certain additive fabrication processes to permit fabrication of a greater range of object geometries. For additive fabrication processes with materials that are subsequently sintered into a final part, an interface layer is fabricated between the object and support in order to inhibit bonding between adjacent surfaces of the support structure and the object during sintering.
1. A method comprising:
fabricating, from a first material, a support structure for an object;
fabricating an interface layer adjacent to the support structure; and
fabricating a surface of the object from a second material, the surface of the object adjacent to the interface layer and the second material including a powdered material for forming a final part and a binder system including one or more binders, wherein the one or more binders retain a net shape of the object during processing of the object into the final part, wherein processing of the object into the final part includes debinding the net shape to remove at least a portion of the one or more binders and sintering the net shape to join and densify the powdered material, and wherein the interface layer resists bonding of the support structure to the object during sintering.
2. The method of claim 1 wherein the second material includes a powdered metallurgy material.
3. The method of claim 1 wherein the powdered material includes a metal powder.
4. The method of claim 1 wherein the powdered material includes a ceramic powder.
5. The method of claim 1 wherein the powdered material is a sinterable material.
6. The method of claim 1 wherein the second material includes an infiltrable powder with at least one of a metallic infiltrant and a ceramic infiltrant.
7. The method of claim 1 wherein the binder system includes a single binder.
8. The method of claim 7 wherein the single binder is removable from the object through a pure thermal debind.
9. The method of claim 7 wherein fabricating the surface of the object includes applying the single binder in a binder jetting process.
10. The method of claim 1 wherein the binder system includes a first binder that is removed from the second material during a debind prior to sintering, and wherein the binder system includes a second binder that remains in the net shape at an onset of a thermal sintering cycle.
11. The method of claim 1 wherein the binder system includes a first binder that is removed from the second material during a debind prior to sintering, and wherein the binder system includes a second binder that remains in the net shape through sintering into the final part.
12. The method of claim 11 wherein the second binder includes submicron particles that facilitate sintering of the powdered material.
13. The method of claim 12 wherein the submicron particles include an element selected for alloying with the powdered material.
14. The method of claim 12 wherein the submicron particles have a composition substantially identical to the powdered material and a size distribution with a mean at least one order of magnitude smaller than the powdered material.
15. The method of claim 1 wherein the powdered material has a distribution of particle sizes with a mean diameter of between two and fifty microns.
16. The method of claim 1 wherein the binder system includes a first binder and a second binder, the first binder resisting deformation of the net shape of the object during debinding of the object and the second binder resisting deformation of the net shape of the object during a beginning of a thermal sintering cycle for the object.
17. The method of claim 16 further comprising debinding the object to remove the first binder.
18. The method of claim 17 wherein debinding the object includes at least one of chemical debinding, thermal debinding, catalytic debinding, supercritical debinding, and evaporation.
19. The method of claim 17 wherein debinding the object includes microwaving the object.
20. The method of claim 16 further comprising heating the object to remove the second binder.
21. The method of claim 1 wherein the binder system includes at least one polymer.
22. The method of claim 1 wherein the binder system includes a first binder and at least one other binder, the first binder forming about 20 percent to about 98 percent by volume of the binder system, the method further comprising debinding the first binder from the object to create open pore channels for a release of the at least one other binder.
23. The method of claim 1 wherein fabricating at least one of the support structure, the object, and the interface layer includes additively manufacturing the support structure using at least one of fused filament fabrication, binder jetting, and optical curing of a powder-loaded resin.
24. The method of claim 1 wherein the interface layer includes a finishing material, and further wherein applying the interface layer includes applying the interface layer to one or more exterior surfaces of the object.
25. The method of claim 24 wherein the finishing material includes an alloying metal having an aesthetic finish.
26. The method of claim 24 wherein fabricating the interface layer includes fully encapsulating the object.
27. The method of claim 24 wherein the interface layer includes titanium.
28. The method of claim 1 wherein at least one of the first material and the interface layer is formed of a composition including microspheres that controllably collapse under pressure to reduce volume.
29. The method of claim 28 further comprising applying pressure to collapse the microspheres, the collapse of the microspheres separating the support structure from the object.
30. The method of claim 1 wherein the interface layer is formed of the first material.