Electrodes for making nanocarbon-infused metals and alloys
A method for preparing a covetic, nanocarbon-infused, metal composite material is described is herein. The method comprises heating a stirring molten mixture of a metal (e.g., Cu, Al, Ag, Au, Fe, Ni, Pt, Sn, Pb, Zn, Si, and the like) and carbon (e.g., graphite) at a temperature sufficient to maintain the mixture in the molten state in a reactor vessel, while passing an electric current through the molten mixture via at least two spaced electrodes submerged or partially submerged in the molten metal. Each of the electrodes has an electrical conductivity that is at least about 50 percent of the electrical conductivity of the molten mixture at the temperature of the molten mixture. Preferably, the conductivity of the electrodes is equal to or greater than the conductivity of the molten mixture.
1. A process for preparing a covetic nanocarbon-infused metal material comprising the steps of:
(a) heating a stirring molten mixture of a metal and carbon at a temperature sufficient to maintain the mixture in the molten state in a reactor vessel;
(b) passing an electric current through the stirring molten mixture via at least two spaced electrodes that are immersed or at least partially immersed in the molten mixture; and
(c) recovering the resulting covetic material from the reactor;
wherein the electrodes are in circuit with an electrical power source that supplies the electric current, each electrode has an electrical conductivity that is at least about 50 percent of an electrical conductivity of the molten mixture at the temperature of the molten mixture; the at least two spaced electrodes comprise a tubular electrode surrounding a longitudinally oriented cylindrical central electrode; and wherein the electrodes are coated with a substance that provides an inert barrier to reaction of the electrodes with the molten mixture and-the substance that provides an inert barrier comprises at least one material selected from the group consisting of a conductive ceramic material, a conductive metal, a conductive intermetallic, and a conductive alloy.
2. The process of claim 1 , wherein the metal of the molten mixture comprises at least one metal selected from the group consisting of Cu, Al, Ag, Au, Fe, Ni, Pt, Sn, Pb, Zn, and Si.
3. The process of claim 1 , wherein the metal of the molten mixture comprises copper; and the electrodes are constructed from one or more metals selected from the group consisting of tungsten and palladium.
4. The process of claim 1 , wherein the metal of the molten mixture comprises aluminum; and the electrodes are constructed from one or more metals selected from the group consisting of (i) aluminum bronze, (ii) titanium diboride, and (iii) copper, molybdenum, silver, gold, platinum, or a combination of two or more thereof.
5. The process of claim 1 , wherein the metal of the molten mixture comprises iron; and the electrodes are constructed from one or more metals selected from the group consisting of tungsten, molybdenum, iridium, ruthenium, and titanium diboride.
6. The process of claim 1 , wherein the carbon is a particulate carbon material.
7. The process of claim 1 , wherein the carbon comprises graphite.
8. The process of claim 1 , wherein the process is conducted under an inert atmosphere having a partial pressure of oxygen of not more than about 0.1 Torr.
9. The process of claim 1 , wherein the process is conducted under an inert atmosphere having a partial pressure of oxygen in a range of about 0.001 Torr to about 0.1 Torr.
10. The process of claim 1 , wherein the molten mixture is heated at a temperature of at least about 50° C. above the melting point of the metal of the molten mixture.
11. The process of claim 1 , wherein the total amount of carbon in the molten mixture comprises about 0.1 to about 10 percent by weight of the molten mixture.
12. The process of claim 1 , wherein the total amount of carbon introduced into the metal comprises about 0.3 to about 4 percent by weight of the molten mixture.
13. The process of claim 1 , wherein the conductivity of each electrode is greater than or equal to the conductivity of the molten mixture.