Systems and methods for making ceramic powders

Patent metadata

Field	Value
Publication number	US-11078124-B2
Application number	US-201916241517-A
Country	US
Kind code	B2
Filing date	Jan 7, 2019
Priority date	Jul 8, 2016
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

Abstract

Systems and methods for making ceramic powders configured with consistent, tailored characteristics and/or properties are provided herein. In some embodiments a system for making ceramic powders, includes: a reactor body having a reaction chamber and configured with a heat source to provide a hot zone along the reaction chamber; a sweep gas inlet configured to direct a sweep gas into the reaction chamber and a sweep gas outlet configured to direct an exhaust gas from the reaction chamber; a plurality of containers, within the reactor body, configured to retain at least one preform, wherein each container is configured to permit the sweep gas to flow therethrough, wherein the preform is configured to permit the sweep gas to flow there through, such that the precursor mixture is reacted in the hot zone to form a ceramic powder product having uniform properties.

First claim

We claim:

1. A method for carbothermically producing a ceramic powder, the method comprising:
a) preheating at least one container in a staging zone, wherein the at least one container comprises a preform;
(i) wherein the preform comprises a mixture, wherein the mixture comprises a carbon source and at least one of (a) a metal oxide and (b) boric acid;
(ii) wherein the preform comprises a plurality of granules, wherein the wherein the plurality of granules define an inter-granular porosity of the preform, wherein the inter-granule porosity is from 0.1 to 0.6 area fraction of the preform based on cross section area of the preform, wherein the plurality of granules are internally porous defining an intra-granular porosity, and wherein the intra-granule porosity is configured to occupy not greater than 0.6 area fraction of the preform based on cross section area of the preform;

b) moving the at least one container into a reactor body, wherein the reactor body comprises a reaction zone;
c) carbothermically reacting the preform in the reaction zone thereby producing a ceramic powder, wherein the carbothermically reacting comprises reducing, via the carbon of the preform, at least one of the metal oxide and the boric acid of the preform to form the ceramic powder, wherein the ceramic powder comprises ceramic particles, wherein the ceramic particles are selected from the group consisting of metal carbide particles, metal boride particles, metal nitride particles, and combinations thereof; and
d) moving the at least one container from the reactor body to a receiving zone.

2. The method of claim 1 , comprising flowing, during at least the carbothermically reacting step, a sweep gas into the at least one container.

3. The method of claim 1 , wherein the carbothermically reacting step comprises a reaction time, wherein the reaction time is from 0.5 to 12 hours.

4. The method of claim 1 comprising, prior to the preheating step, forming the preform from a precursor mixture, wherein the precursor mixture comprises the carbon source and at least one of the metal oxide and the boric acid.

5. The method of claim 4 , wherein the forming comprises at least one of: compacting the precursor mixture, molding the precursor mixture, casting the precursor mixture, and extruding the precursor mixture.

6. The method of claim 5 comprising, after the forming step, processing the preform, wherein the processing comprises at least one of: dehydrating, curing, and demolding of the preform.

7. The method of claim 1 comprising, after the carbothermically reacting step, deagglomerating the ceramic powder.

8. The method of claim 1 , wherein the metal oxide is titanium dioxide, and wherein the preform comprises the carbon source and the titanium dioxide.

9. The method of claim 8 , wherein the preform comprises the carbon source, the titanium dioxide, and the boric acid.

10. The method of claim 9 , wherein the preform comprises 10-35 wt. % of the carbon source, 20-50 wt. % of the titanium dioxide, and 30-70 wt. % of the boric acid.

11. The method of claim 1 , wherein the ceramic particles are titanium diboride particles and wherein the ceramic powder is a titanium diboride powder.

Assignees

• Alcoa Usa Corp

Inventors

• Mcmillen James C
• Sworts Lance M
• Mosser Benjamin D
• Shanta Iii Charles Robert

Classifications

• C04B35/6261

  Milling · CPC title

• C04B35/62645

  Thermal treatment of powders or mixtures thereof other than sintering · CPC title

• B01J4/007 Primary

  provided with moving parts · CPC title

• C04B2235/3232

  Titanium oxides or titanates, e.g. rutile or anatase · CPC title

• C22C29/02

  based on carbides or carbonitrides · CPC title