Low absorption spinel formed by acidic and basic treatments

Patent metadata

Field	Value
Publication number	US-10486977-B2
Application number	US-201615220072-A
Country	US
Kind code	B2
Filing date	Jul 26, 2016
Priority date	Jul 29, 2015
Publication date	Nov 26, 2019
Grant date	Nov 26, 2019

Abstract

A method of purifying a spinel powder includes contacting a spinel powder with an acid solution to form an acid-washed spinel composition and contacting the acid-washed spinel composition with a basic solution to form a purified composition. The purified powder is suited to formation of low-absorption shaped bodies, such as windows for high intensity laser devices.

First claim

What is claimed is:

1. A method of purifying a spinel powder, the method comprising:
a) contacting a spinel powder with an acid solution to form an acid-washed spinel composition;
b) contacting the acid-washed spinel composition with a basic solution, wherein the basic solution is metal-free; and
c) removing alumina to form a purified composition.

2. The method of claim 1 , wherein the contacting of the powder with an acid solution to form an acid-washed composition further comprises removing residual acid by at least one of:
i) centrifuging the acid-washed spinel composition; and
ii) washing the acid-washed spinel composition with water.

3. The method of claim 1 , wherein the acid solution has a pH of less than 6.

4. The method of claim 1 , wherein the contacting with the acid solution comprises contacting at a temperature in a range of from 15° C. to a boiling point of the acid solution.

5. The method of claim 1 , wherein the acid solution comprises at least one of nitric acid, hydrochloric acid, and acetic acid.

6. The method of claim 1 , wherein the acid solution comprises at least 0.001M acid.

7. The method of claim 1 , wherein the contacting with the basic solution comprises:
i) contacting the acid-washed composition with the base solution to form a base-washed spinel composition;
ii) centrifuging the base-washed spinel composition; and
iii) repeating steps i) and ii) until the base-washed spinel composition has a pH within a selected range.

8. The method of claim 7 , wherein the selected pH range is from 7.0 to 8.5.

9. The method of claim 1 , wherein the basic solution has a pH of at least 7.2.

10. The method of claim 1 , wherein the basic solution comprises at least 0.001M base.

11. The method of claim 1 , wherein the basic solution comprises a basic compound which is metal-free.

12. The method of claim 1 , wherein the basic solution comprises at least one of ammonium carbonate and ammonium bicarbonate.

13. The method of claim 1 , further comprising, after b), washing the base-washed spinel composition with a solvent.

14. The method of claim 13 , wherein the solvent is an aprotic solvent.

15. The method of claim 1 , further comprising, after c), at least one of:
d) drying the purified composition at a drying temperature of at least 100° C.;
e) comminuting the purified composition; and
f) baking the purified composition at a baking temperature of at least 600° C.

16. The method of claim 1 , wherein the spinel powder comprises at least 90 wt % MgAl 2 O 4 .

17. The method of claim 1 , wherein the method further comprises:
forming a shaped body from the purified composition.

18. The method of claim 17 , wherein the forming comprises at least one of hot pressing, hot isostatic pressing, sintering, and polishing.

19. The method of claim 17 , wherein the shaped body is at least one of a window, a lens, a transparent armor component, a vehicle component, an aircraft component, a satellite component, a missile component, and an armored canopy component.

20. The method of claim 17 , wherein the shaped product has an absorption of less than 200 ppm/cm at 1.06 μm as measured by Photothermal Common-path Interferometry.

21. The method of claim 1 , additionally comprising removing rare-earth oxides including Lu 2 O 3 , Y 2 O 3 , Sc 2 O 3 , or any combination thereof from the acid-washed spinel composition that was contacted with the basic solution.

22. A method of forming a shaped body comprising:
a) contacting a powder comprising a spinel with an acid solution to form an acid-washed spinel composition;
b) contacting the acid-washed spinel composition with a basic solution, wherein the basic solution is metal-free;
c) removing alumina to form a purified composition having a pH of from 7-8.5; and
d) sintering the purified composition to form the shaped body.

Assignees

• Us Gov Sec Navy

Inventors

• Kim Woohong
• Villalobos Guillermo R
• Baker Colin C
• Bayya Shyam S
• Hunt Michael
• Sadowski Bryan
• Aggarwal Ishwar D
• Sanghera Jasbinder S

Classifications

• C04B2235/763

  Spinel structure AB2O4 · CPC title

• C04B2235/5445

  submicron sized, i.e. from 0,1 to 1 micron · CPC title

• C01F7/162 Primary

  Magnesium aluminates · CPC title

• C01P2006/80

  Compositional purity · CPC title

• C04B35/6455

  Hot isostatic pressing · CPC title