Soft magnetic composite materials and methods and powders for producing the same
A powder including a plurality of particulates, each particulate including a soft magnetic metallic core coated with a continuous dielectric coating having a thickness selected from a range of 100 nanometers to 100 micrometers. The particulates have a mean particle size selected from a range of 100 nanometers to 250 micrometers. Methods for forming the powder are disclosed. A soft magnetic composite component includes a soft magnetic material in a dielectric matrix, wherein (i) the soft magnetic material comprises a plurality of particulates comprising metallic cores, (ii) each metallic core is coated by a continuous dielectric coating covering >90% of a surface area of the metallic core, (iii) the metallic cores are electrically isolated from each other, and (iv) the dielectric coatings of adjacent metallic cores are consolidated together. Methods for formation of the soft magnetic component by additive manufacturing and hot isostatic pressing are disclosed.
1. A method for fabricating a soft magnetic composite component by additive manufacturing, the method comprising:
providing to an additive manufacturing system a powder comprising a plurality of particulates, each particulate comprising a soft magnetic metallic core coated with a continuous conformal dielectric coating comprising a dielectric material covering more than 90% of a surface area of the metallic core, wherein the continuous conformal dielectric coating is formed by deposition; and
fabricating the soft magnetic composite component by forming consolidated material from the powder by additive manufacturing,
wherein (i) additive manufacturing comprises Binder Jetting, (ii) a porosity of the magnetic composite component is less than 5% by volume, and (iii) the soft magnetic metallic cores in the magnetic composite component are electrically and magnetically isolated from each other by a continuous three-dimensional network of the dielectric material.
2. The method of claim 1 , wherein the metallic core comprises a soft magnetic pure metal or alloy comprising at least one of Fe, Co, Ni, Fe—Co, Fe—Co—V, Fe—Ni, Fe—Si, FeCoSiB, FeSiAl, amorphous magnetic materials, metal-metalloid systems (metallic glasses), or alloys or combinations thereof.
3. The method of claim 1 , wherein the metallic core comprises a coercivity selected from a range of 0.01 Oe to 50 Oe.
4. The method of claim 1 , wherein the continuous three-dimensional network of the dielectric material comprises physical interfaces disposed between proximate particulates.
5. The method of claim 1 , wherein the continuous dielectric coating comprises a first surface layer comprising a dielectric material comprising at least one of a hydride, an oxide, a nitride, a boride, a carbide, carbon, a sulfide, a fluoride, a polymer, phosphorus, or combinations thereof.
6. The method of claim 1 , wherein a thickness of the continuous dielectric coating is less than 1 micrometer.
7. The method of claim 1 , wherein fabricating the soft magnetic composite component comprises a densification step after additive manufacturing.
8. The method of claim 1 , wherein the magnetic composite component has a tensile breaking strength greater than 150 MPa.
9. The method of claim 1 , wherein the particulates comprise a unimodal particle size distribution with a mean particle size selected from a range of 100 nanometers to 250 micrometers.
10. The method of claim 1 , wherein the powder further comprises a plurality of uncoated soft magnetic particulates, and a smaller mean particle size of the powder is a mean particle size of the uncoated soft magnetic particulates and a larger mean particle size of the powder is a mean particle size of the coated particulates, the plurality of uncoated soft magnetic particulates and the coated particulates comprising a same alloy.
11. The method of claim 1 , wherein the continuous dielectric coating comprises a plurality of heterogeneous surface layers.
12. The method of claim 1 , wherein a shape of each particulate is at least one of flat or oblong.
13. The method of claim 1 , wherein a ratio of dielectric material to metal in the component is selected from a range of 1:1-1:2,500.
14. The method of claim 7 , wherein densification comprises an isostatic method.
15. The method of claim 1 , wherein deposition of the continuous conformal dielectric coating comprises at least one of atomic layer deposition (ALD), molecular layer deposition, physical vapor deposition, sol-gel, chemical vapor deposition (CVD), metal organic chemical vapor deposition (MOCVD), plasma torch synthesis, spray coating, high velocity oxygen fuel coating, arc coating, co-precipitation, epoxy coating, a supercritical CO 2 method, high pressure coating, or combinations thereof or (i) functionalizing each magnetic metallic core by applying a plurality of dielectric nanoparticles to the core, and (ii) densifying the dielectric nanoparticles to form the continuous dielectric coating.
16. The method of claim 1 , wherein a thickness of the continuous conformal dielectric coating is at least 100 nanometers.