High-density low epsilon ballast materials

• US 6,541,555 B1
• Filed: 12/20/1999
• Issued: 04/01/2003
• Est. Priority Date: 12/20/1999
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Roetcisoender, Kirk T.
• Primary Examiner(s): Cain, Edward J.
• Assistant Examiner(s): WYROZEBSKI LEE, KATARZYNA I
• Application Number:
  US09/466,891
• Time in Patent Office: 1,198 Days
• Field of Search: 524/398, 524/401, 524/402, 524/404, 524/406, 524/413, 524/423, 524/424, 524/427, 524/430, 524/431, 524/440
• US Class Current: 524/398
• CPC Class Codes: C08K 3/18 Oxygen-containing compounds, e.g. metal carbonyls
• CPC Class Codes: H01Q 17/00 Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems

Abstract

High density, low epsilon ballast materials are disclosed. The materials comprise dielectric ceramic particles in a polymeric matrix. The composite material possesses higher density/dielectric ratios in comparison with conventional ballast materials.

Claims

1. A high density, low epsilon ballast material comprising at least about 30 volume percent dielectric ceramic particles in a polymeric matrix, wherein the material has a composite epsilon value of less than about 7 and a density of greater than about 5 g/cc.

2. The material of claim 1, wherein the dielectric ceramic particles comprise oxides, sulfides, fluorides, nitrides and/or borides.

3. The material of claim 1, wherein the dielectric ceramic particles comprise PbO, PbS and/or HgS.

4. The material of claim 1, wherein the dielectric ceramic particles comprise HgO and/or WO₂.

5. The material of claim 1, wherein the polymeric matrix comprises epoxies, urethanes, silicones, and/or polytetrafluoroethylene.

6. The material of claim 1, wherein the polymeric matrix comprises polytetrafluoroethylene with perfluoro(alkyl vinyl esters) and/or low dielectric urethane resins.

7. The material of claim 1, wherein the dielectric ceramic particles comprise from about 30 to about 50 volume percent of the material.

8. The material of claim 1, wherein the dielectric ceramic particles comprise from about 35 to about 40 volume percent of the material.

9. The material of claim 1, wherein the dielectric ceramic particles have an average size of from about 5 to about 100 microns.

10. The material of claim 1, wherein the dielectric ceramic particles have an average size of from about 10 to about 20 microns.

11. The material of claim 1, wherein the dielectric ceramic particles are substantially uniformly dispersed throughout the polymeric matrix.

12. The material of claim 1, further comprising metallic particles.

13. The material of claim 12, wherein the metallic particles comprise W, Re, Os and/or Pb.

14. The material of claim 12, wherein the metallic particles comprise from about 20 to about 40 volume percent to the material.

15. The material of claim 1, further comprising semiconductor particles.

16. The material of claim 15, wherein the semiconductor particles comprise, SiC, C and/or BN.

17. The material of claim 15, wherein the semiconductor particles comprise from about 0.5 to about 2 volume percent of the material.

18. The material of claim 1, wherein the material has a composite epsilon value of less than about 5.

19. The material of claim 1, wherein the dielectric ceramic particles have an epsilon value of from about 5 to about 20.

20. The material of claim 1, wherein the dielectric ceramic particles have an epsilon value of from about 5 to about 12.

21. The material of claim 1, wherein the material has a density of greater than about 6 g/cc.

22. The material of claim 1, wherein the material has a density of greater than about 7 g/cc.

23. The material of claim 1, wherein the material has a composite epsilon value of less than about 6.

24. The material of claim 1, wherein the material has a composite epsilon value of less than about 5.

25. The material of claim 1, wherein the material has a density/dielectric ratio of greater than 0.9.

26. The material of claim 1, wherein the material has a density/dielectric ratio of greater than 1.1.

27. A method of making a high density, low epsilon ballast material comprising:

mixing dielectric ceramic particles with a resin; and

curing the resin to form a composite material comprising the dielectric ceramic particles in a matrix of the cured resin, wherein the material has a composite epsilon value of less than about 7 and a density of greater than about 5 g/cc.