Semi-passive control of solidification in powdered materials
Disclosed herein are surface-functionalized powders which alter the solidification of the melted powders. Some variations provide a powdered material comprising a plurality of particles fabricated from a first material, wherein each of the particles has a particle surface area that is continuously or intermittently surface-functionalized with nanoparticles and/or microparticles selected to control solidification of the powdered material from a liquid state to a solid state. Other variations provide a method of controlling solidification of a powdered material, comprising melting at least a portion of the powdered material to a liquid state, and semi-passively controlling solidification of the powdered material from the liquid state to a solid state. Several techniques for semi-passive control are described in detail. The methods may further include creating a structure through one or more techniques selected from additive manufacturing, injection molding, pressing and sintering, capacitive discharge sintering, or spark plasma sintering.
1. A solid object or article comprising a structure produced by an additive manufacturing or injection molding process comprising:
providing a powdered material comprising a plurality of particles, wherein said particles are fabricated from a first material, and wherein each of said particles has a particle surface area that is surface-functionalized with a second material containing nanoparticles and/or microparticles;
melting at least a portion of said powdered material to a liquid state, thereby generating a melt;
allowing said nanoparticles and/or microparticles to be transported to a surface of said melt, to form a melt layer of said nanoparticles and/or microparticles; and
semi-passively controlling solidification of said melt and said melt layer from said liquid state to a solid state, in additive manufacturing or injection molding, to fabricate said structure,
wherein said structure comprises a continuous solid phase and a layer of solid nanoparticles and/or solid microparticles disposed at an outer surface of said continuous solid phase.
2. A solid object or article comprising a continuous solid phase and a first layer of nanoparticles and/or microparticles disposed at an outer surface of said continuous solid phase, wherein said continuous solid phase is a melted and resolidified form of a powdered material comprising a plurality of particles, wherein said particles are fabricated from a first material, wherein each of said particles has a particle surface area that is surface-functionalized with said nanoparticles and/or microparticles selected to control solidification of said powdered material from a liquid state to a solid state, and wherein said nanoparticles and/or microparticles are fabricated from a second material that is different than said first material.
3. The solid object or article of claim 2 , wherein said first layer of nanoparticles and/or microparticles has a higher emissivity compared to said continuous solid phase.
4. The solid object or article of claim 2 , wherein said first layer of nanoparticles and/or microparticles has a higher thermal conductivity compared to said continuous solid phase.
5. The solid object or article of claim 2 , wherein said nanoparticles and/or microparticles are selected for epitaxial fit of crystal lattice parameters with said first material.
6. The solid object or article of claim 2 , wherein said nanoparticles and/or microparticles are nucleation sites within said continuous solid phase.
7. The solid object or article of claim 2 , wherein said first layer of nanoparticles and/or microparticles forms from about 0.1 wt % to about 50 wt % of said solid object or article.
8. The solid object or article of claim 2 , wherein said first material is selected from the group consisting of ceramic, metal, polymer, glass, and combinations thereof.
9. The solid object or article of claim 2 , wherein said second material is selected from the group consisting of metal, ceramic, polymer, carbon, and combinations thereof.
10. The solid object or article of claim 2 , wherein said solid object or article further comprises a second layer of said nanoparticles and/or microparticles disposed at another outer surface of said continuous solid phase.