Spinel Ceramics Via Edge Bonding

• US 20120196105A1
• Filed: 01/19/2012
• Published: 08/02/2012
• Est. Priority Date: 01/31/2011
• Status: Active Grant

• Current Assignee: Navy The USA As Represented By The Secretary of The
• Original Assignee: The United States of America As Represented By The Secretary of Agriculture
• Inventors: Sanghera, Jasbinder S., Bayya, Shyam S., Villalobos, Guillermo R., Aggarwal, Ishwar D., Miklos, Robert E.
• Granted Patent: US 8,652,281 B2
• Time in Patent Office: Days
• US Class Current: 428/215
• CPC Class Codes: B32B 18/00 Layered products essentially comprising ceramics, e.g. refractory products
• CPC Class Codes: B32B 37/14 characterised by the properties of the layers
• CPC Class Codes: C04B 2235/6562 Heating rate
• CPC Class Codes: C04B 2235/6565 Cooling rate
• CPC Class Codes: C04B 2235/6567 Treatment time
• CPC Class Codes: C04B 2235/963 Surface properties, e.g. surface roughness
• CPC Class Codes: C04B 2237/343 Alumina or aluminates
• CPC Class Codes: C04B 2237/52 Pre-treatment of the joining surfaces, e.g. cleaning, machining
• CPC Class Codes: C04B 2237/704 of one or more of the ceramic layers or articles
• CPC Class Codes: C04B 2237/76 Forming laminates or joined articles comprising at least one member in the form other than a sheet or disc, e.g. two tubes or a tube and a sheet or disc
• CPC Class Codes: C04B 35/645 Pressure sintering
• CPC Class Codes: C04B 37/001 directly with other burned ceramic articles
• CPC Class Codes: Y10T 156/1064 Partial cutting [e.g., grooving or incising]
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/24967 Absolute thicknesses specified

Abstract

Disclosed herein is a method for making transparent ceramic spinel windows, domes and other complex shapes via edge bonding.

Claims

1. A method of making spinel ceramics comprising:

polishing one edge of a first spinel part to a surface roughness of less than 1 nm;

polishing one edge of a second spinel part to a surface roughness of less than 1 nm;

joining the polished edge of the first spinel part to the polished edge of the second spinel part;

heating the first and second spinel parts to about 1000-1200°

C.; and

maintaining said heating for about 3-6 hours resulting in bonded spinel parts.

2. The method of claim 1 further including the step of cooling to room temperature.

3. The method of claim 2 wherein said heating is at a rate of about 5°

C./min and said cooling is at a rate of about 1°

C./min.

4. The method of claim 3 further including the step of polishing the bonded spinel parts.

5. The method of claim 4 wherein said bonded spinel parts is a spinel ogive dome.

6. The method of claim 5 wherein said spinel ogive dome is a monolithic part with an invisible or almost invisible bondline.

11. A spinel ceramic made from the process of claim 1 wherein said spinel ceramic comprises a monolithic spinel ogive dome with an invisible or nearly invisible bondline wherein said spinel (MgAl₂O₄) is a rugged, hard and strong ceramic material which transmits from the UV to the infrared in the range of from about 0.2 to about 5 μ

m.

7. A method of making a spinel ceramic comprising:

polishing a first edge of a first spinel transparent tile of about 3″

×

3″

×

½

″

thick wherein said polishing results in <

1 nm surface roughness;

polishing a first edge of a second spinel transparent tile of about 3″

×

3″

×

½

″

thick wherein said polishing results in <

1 nm surface roughness;

bonding the polished edges;

applying a load;

heating up to 1100°

C. at 5°

C./min and held for 6 hours; and

cooling slowly to room temperature at 1°

C./min resulting in a spinel ceramic.

8. The method of claim 7 further including polishing multiple edges of additional spinel transparent tiles wherein said polishing results in <

1 nm surface roughness and bonding the polished edges to form a monolithic ceramic.

9. The method of claim 8 further including polishing the spinel ceramic to remove surface debris and artifacts.

10. The method of claim 9 wherein the spinel ceramic exhibits optical transparency from the UV to about 5 μ

m, similar to the first spinel transparent tile and the second spinel transparent tile prior to bonding.