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 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 a second material containing nanoparticles and/or microparticles, wherein said second material is different than said first material, wherein the melting point of said second material is higher than the melting point of said first material, and wherein said nanoparticles and/or microparticles are selected for epitaxial fit of crystal lattice parameters with said first material.
2. The powdered material of claim 1 , wherein said first material is selected from the group consisting of ceramic, metal, polymer, glass, and combinations thereof.
3. The powdered material of claim 1 , wherein said second material is selected from the group consisting of metal, ceramic, polymer, carbon, and combinations thereof.
4. The powdered material of claim 1 , characterized in that on average at least 1% of said particle surface area is surface-functionalized with said nanoparticles and/or said microparticles.
5. The powdered material of claim 1 , wherein said particles are present as a loose powder, a paste, a suspension, a green body, or a combination thereof.
6. The powdered material of claim 1 , wherein said particles have an average particle size from about 1 micron to about 1 centimeter.
7. The powdered material of claim 1 , wherein said nanoparticles and/or microparticles have an average maximum particle dimension from about 1 nanometer to about 100 microns.
8. The powdered material of claim 1 , wherein said nanoparticles and/or microparticles have an average minimum particle dimension from about 1 nanometer to about 1 micron.
9. The powdered material of claim 1 , wherein said nanoparticles and/or microparticles are nucleation sites within said powdered material.
10. The powdered material of claim 1 , wherein said nanoparticles and/or microparticles are characterized by an average diameter that is less than 20% of an average diameter of said particles.
11. The powdered material of claim 1 , wherein said second material is in the form of an intermittent coating.