Transparent nanocomposite ceramics built from core/shell nanoparticles

Patent metadata

Field	Value
Publication number	US-10513462-B2
Application number	US-201615260487-A
Country	US
Kind code	B2
Filing date	Sep 9, 2016
Priority date	Sep 11, 2015
Publication date	Dec 24, 2019
Grant date	Dec 24, 2019

Abstract

A method for making transparent nanocomposite ceramics and other solid bulk materials from nanoparticle powders and transparent nanocomposite ceramics and other solid bulk materials formed using that method. A nanoparticle powder is placed into a reaction chamber and is treated to produce a clean surface powder. The clean surface powder is coated with a second material by means of p-ALD to produce core/shell or core multi shell nanoparticles having a coating or coatings of a other material surrounding the nanoparticle. The core/shell nanoparticles are cleaned and formed into green compact which is sintered to produce a transparent nanocomposite ceramic or other solid bulk material consisting of nanoparticles or core/shell nanoparticles uniformly embedded in a matrix of a different material, particularly in a matrix of a different ceramic material, formed by outer shell of initial core/shell. All steps are performed without exposing the material to the ambient.

First claim

What is claimed is:

1. A process for making a transparent nanocomposite solid bulk material, the process including:
providing a powder comprising a plurality of nanoparticles of at least one material;
placing the powder inside an enclosure having a controlled gas atmosphere;
without exposing the powder to an ambient air, subjecting the powder to a first predetermined cleaning temperature T c1 for a first predetermined cleaning time t c1 to clean the nanoparticles and provide a cleaned powder comprising cleaned nanoparticles having a surface free from contaminants;
without exposing the cleaned powder to the ambient atmosphere, transferring the cleaned powder to a powder Atomic Layer Deposition (p-ALD) reactor and coating the cleaned nanoparticles with one or more shell nanolayers to form a plurality of core/shell nanocomposite particles each comprising a core nanoparticle having an outer shell formed from one or more nanolayers of a material different from a material forming the core;
without exposing the core/shell nanocomposite particles to the ambient atmosphere, subjecting the core/shell nanocomposite particles to a predetermined pressure P greater than 100 bar and a predetermined sintering temperature T s for a predetermined sintering time t s , the sintering temperature T s being less than about 0.4 times the melting point T m of the material;
wherein the pressure P, sintering temperature T s , and sintering time t s are configured to sinter the core/shell nanocomposite particles to a transparent nanocomposite solid bulk material having a density of not less than 99% without any coarsening or growth of a grain size of the nanoparticles;
wherein the solid bulk material comprises the core nanoparticles uniformly embedded in a matrix of a solid material comprising the material of the outer shell of the initial core/shell nanoparticles; and
wherein the solid bulk material retains the original grain sizes, original nanostructure, and original spatial phase arrangement of the individual core/shell nanoparticles within the matrix material.

2. The process according to claim 1 , wherein the temperature T c1 is greater than 100° C.

3. The process according to claim 1 , wherein the time t c1 is greater than 10 minutes.

4. The process according to claim 1 , further comprising subjecting the core/shell nanocomposite particles to a second predetermined cleaning temperature T c2 for a second predetermined cleaning time t c2 without exposing them to the ambient atmosphere to clean the core/shell nanocomposite particles and provide core/shell nanocomposite particles having a surface free from contaminants.

5. The process according to claim 4 , wherein the temperature T c2 is greater than 100° C.

6. The process according to claim 4 , wherein the time t c2 is greater than 10 minutes.

7. The process according to claim 1 , wherein the temperature T s is between 100° C. and 1300° C.

8. The process according to claim 1 , wherein the pressure P is between 2 and 100 bar.

9. The process according to claim 1 , wherein the pressure P is between 100 bar and 6 GPa.

10. The process according to claim 1 , wherein the controlled gas atmosphere comprises H 2 , Ar, N 2 , CH 4 , O 2 , or mixtures thereof.

11. The process according to claim 1 , further comprising making a preformed green compact from the core/shell nanocomposite particles without exposing the core/shell nanocomposite particles to the ambient atmosphere;
wherein the green compact is subjected to the predetermined pressure P and a predetermined sintering temperature T s for a predetermined sintering time t s to produce the transparent nanocomposite solid bulk material.

12. The process according to claim 1 , wherein the nanoparticles comprise particles of a plurality of materials.

13. The process according to claim 1 , wherein the nanoparticles include particles of at least one metal.

14. The process according to claim 1 , wherein the nanoparticles include particles of at least one nonmetal.

15. The process according to claim 1 , wherein the nanoparticles comprise a mixture of metals and nonmetals.

16. The process according to claim 1 , wherein the nanoparticles have a diameter of less than 50 nm.

17. The process according to claim 1 , wherein a grain size of the transparent nanocomposite solid bulk material is less than 50 nm.

18. The process according to claim 1 , wherein the nanocomposite solid bulk material is a nanocomposite ceramic.

19. The process according to claim 18 , wherein the transparent nanocomposite ceramic is an oxide ceramic.

20. The process according to claim 1 , wherein the solid bulk material is a nanocomposite ceramic comprising core nanoparticles formed from a first ceramic material uniformly embedded in a matrix of a second ceramic material.

21. The process according to claim 20 , wherein the solid bulk material comprises MgAl 2 O 4 spinel nanoparticles uniformly embedded in alumina Al 2 O 3 matrix.

22. A product made by the process of claim 1 .

23. A product made by the process of claim 11 .

Assignees

• Us Gov Sec Navy

Inventors

• Feigelson Boris N
• Wollmershauser James A
• Manandhar Kedar
• Kub Francis J

Classifications

• C04B35/443 Primary

  Magnesium aluminate spinel · CPC title

• C23C16/45525

  Atomic layer deposition [ALD] · CPC title

• C04B2235/656

  characterised by specific heating conditions during heat treatment · CPC title

• C04B35/645

  Pressure sintering · CPC title

• C04B35/62813

  Alumina or aluminates · CPC title