Method for forming multi-material electromagnetic shield
Systems and methods of additively manufacturing multi-material electromagnetic shields are described. Additive manufacturing processes use co-deposition to incorporate multiple materials and/or microstructures selected to achieve specified shield magnetic properties. Geometrically complex shields can be manufactured with alternating shielding materials optimized for the end use application. The microstructures of the printed shields can be tuned by optimizing the print parameters.
1. A method for forming a multi-material electromagnetic shield comprising:
providing at least one powderized feedstock of a magnetic alloy;
determining at least one printing parameter for an additive manufacturing process;
depositing the at least one powderized feedstock in a vertical orientation using the determined at least one printing parameter to additively manufacture an electromagnetic shield with at least one shield wall; and
post-processing the electromagnetic shield by at least one of stress relief anneal, hot isostatic pressing, full anneal, and surface finishing;
wherein the at least one powderized feedstock is delivered by at least one powder feeder;
wherein the additive manufacturing process uses a laser as a power source;
wherein the deposition is in a chamber filled with an inert gas; and
wherein the thickness of the at least one shield wall is controlled by a spot size of the laser.
2. The method of claim 1 , wherein the at least one printing parameter is selected from the group consisting of laser power, laser spot size, laser scan speed, hatch spacing, layer thickness, and powder mass flow rate.
3. The method of claim 2 , wherein the laser power is tuned to optimize magnetic saturation, coercivity, and magnetic permeability of the electromagnetic shield.
4. The method of claim 2 , wherein the laser power is at least 600 W.
5. The method of claim 2 , wherein the laser power is about 650 W.
6. The method of claim 2 , wherein the laser spot size is at least 0.04 inch in diameter.
7. The method of claim 2 , wherein the laser scan speed is tuned to control hierarchical microstructures of the electromagnetic shield.
8. The method of claim 2 , wherein the laser scan speed is between about 16 ipm and about 76 ipm.
9. The method of claim 2 , wherein the hatch spacing is at least 0.025 inch.
10. The method of claim 2 , wherein the layer thickness is at least 0.01 inch.
11. The method of claim 2 , wherein the powder mass flow rate is between about 10 g/min and about 14 g/min.
12. The method of claim 1 , wherein the magnetic alloy is selected from the group consisting of a Ni—Fe based magnetic alloy, a Co—Fe based magnetic alloy, a Cu based alloy, and an Al based alloy.
13. The method of claim 12 , wherein the Ni—Fe based magnetic alloy is Fe-80Ni-5Mo or Fe-49Ni.
14. The method of claim 12 , wherein the Co—Fe based magnetic alloy is Fe-49Co-2V.
15. The method of claim 1 , wherein the additive manufacturing process is selected from the group consisting of blown powder directed energy deposition (DED), laser engineered net shaping (LENS), and wire feed DED.
16. The method of claim 1 , wherein the at least one powderized feedstock has a spherical shape and the spherical powder has a diameter between about 45 microns and about 150 microns.
17. The method of claim 1 , wherein the chamber is filled with argon.
18. The method of claim 1 , wherein the chamber has an oxygen concentration of less than about 10 ppm.
19. The method of claim 1 , wherein the chamber has a build volume of about 600 mm by 600 mm by 600 mm.
20. The method of claim 1 , wherein the stress relief anneal is at about 788° C. for about 1 hour.
21. The method of claim 1 , wherein the hot isostatic pressing is at about 2050° F., about 14.75 ksi for about 3 to 4 hours.
22. The method of claim 1 , wherein the full anneal is at about 2150° F. for about 5 hours.
23. The method of claim 1 , wherein four powder feeders simultaneously deliver four different powderized feedstocks.
24. The method of claim 1 , wherein the at least one shield wall has a thickness of about 1.5 mm.
25. The method of claim 1 , wherein the electromagnetic shield has a cylindrical shape, a rectangular shape, or a box shape.
26. The method of claim 1 , wherein the electromagnetic shield has two shield walls, wherein each shield wall comprises alternating layers of a high magnetic permeability alloy with a high magnetic saturation alloy.
27. The method of claim 26 , wherein the high magnetic permeability alloy is Fe-80Ni-5Mo, and the high magnetic saturation alloy is Fe-49Ni or Fe-49Co-2V.
28. The method of claim 1 , wherein the electromagnetic shield has two shield walls, wherein an inner shield wall comprises a high magnetic saturation alloy and an outer shield wall comprises a high magnetic permeability alloy.
29. The method of claim 28 , wherein the high magnetic saturation alloy is Fe-49Ni, and the high magnetic permeability alloy is Fe-80Ni-5Mo.
30. The method of claim 1 , wherein the electromagnetic shield has two shield walls, wherein the two shield walls comprise a high magnetic permeability alloy, and an inner wall has a different microstructure than an outer wall.