Low-density resin impregnated ceramic article having an average density of 0.15 to 0.40 g/cc

• US 5,536,562 A
• Filed: 03/14/1994
• Issued: 07/16/1996
• Est. Priority Date: 03/14/1994
• Status: Expired due to Term

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Rasky, Daniel J., Tran, Huy K., Hsu, Ming-ta S., Henline, William D., Riccitiello, Salvatore R.
• Primary Examiner(s): WITHERS, JAMES
• Application Number:
  US08/212,640
• Time in Patent Office: 855 Days
• Field of Search: 428/218, 428/288, 428/290, 428/310.5, 428/311.5, 428/902, 428/245, 428/289, 428/307.3, 428/313.9, 244/121, 244/133, 501/95
• US Class Current: 428/218
• CPC Class Codes: B64G 1/226 Special coatings for spacecraft
• CPC Class Codes: B64G 1/58 Thermal protection, e.g. heat shields
• CPC Class Codes: C04B 2235/616 Liquid infiltration of green bodies or pre-forms
• CPC Class Codes: C04B 2235/775 Products showing a density-gradient
• CPC Class Codes: C04B 35/524 obtained from polymer precursors, e.g. glass-like carbon material
• CPC Class Codes: C04B 35/6269 Curing of mixtures
• CPC Class Codes: C04B 35/80 Fibres, filaments, whiskers, platelets, or the like
• CPC Class Codes: C04B 35/83 Carbon fibres in a carbon matrix
• CPC Class Codes: Y10S 428/902 High modulus filament or fiber
• CPC Class Codes: Y10T 428/24992 Density or compression of components
• CPC Class Codes: Y10T 428/249956 Void-containing component is inorganic
• CPC Class Codes: Y10T 428/249961 With gradual property change within a component
• CPC Class Codes: Y10T 428/249974 Metal- or silicon-containing element
• CPC Class Codes: Y10T 442/2975 Coated or impregnated ceramic fiber fabric

Abstract

A low-density resin impregnated ceramic article advantageously employed as a structural ceramic ablator comprising a fired preform of ceramic fibers. The fibers of the ceramic preform are coated with an organic resin film. The organic resin can be a thermoplastic resin or a cured thermosetting resin. In one embodiment, the resin is uniformly distributed within the ceramic article. In a second embodiment, the resin is distributed so as to provide a density gradient along at least one direction of the ceramic article. The resin impregnated ceramic article is prepared by providing a fired preform of ceramic fibers; immersing the preform of ceramic fibers in a solution of a solvent and an organic resin infiltrant; and removing the solvent to form a resin film on the ceramic fibers.

Claims

1. A low-density resin impregnated ceramic article comprising a fired preform of ceramic fibers and an organic resin film coating said fibers, wherein the resin impregnated ceramic article has an average density of from 0.15 to 0.40 g/cc, an average void volume fraction of 70 to 94 percent, an average ceramic fiber content of 20 to 80 weight percent and an average organic resin content of 80 to 20 weight percent.

2. The low-density resin impregnated ceramic article as in claim 1, wherein said ceramic fibers are selected from the group consisting of silicon dioxide fibers, aluminoborosilicate fibers, alumina fibers and carbon fibers.

3. The low-density resin impregnated ceramic article as in claim 1, wherein the organic resin film comprises a thermoplastic resin or a cured thermosetting resin.

4. The low-density resin impregnated ceramic article as in claim 3, wherein the thermoplastic resin is selected from the group consisting of polymethylmethacrylate resin, polybenzimidazole resin and polystyrene resin.

5. The low-density resin impregnated ceramic article as in claim 3, wherein the thermosetting resin is selected from the group consisting of novolak epoxy resin, phenolic resin, silicone resin and polyarylacetylene resin.

6. The low-density resin impregnated ceramic article as in claim 1, having an average void volume fraction of from 88 to 92 percent.

7. The low-density resin impregnated ceramic article as in claim 1, wherein the fibers constituting the fired preform of ceramic fibers are coated with said organic resin film in a coating thickness of from 0.1 μ

m to 200 μ

m.

8. The low-density resin impregnated ceramic article as in claim 1, containing an organic resin in an average amount of from 60 to 30 weight percent of the weight of the ceramic article.

9. The low-density resin impregnated ceramic article as in claim 1, having an organic resin content uniform to within ±

10 wt % of the average resin content (in wt %) of the ceramic article.

10. The low-density resin impregnated ceramic article as in claim 1, having a density gradient defined as a change in density (g/cc) per unit distance along at least one direction thereof of from 0.05 to 0.8 per cm.

11. The low-density resin impregnated ceramic article as in claim 1, wherein the density at an outer surface of the ceramic article is from 0.27 to 0.82 g/cc and the density at the center of the ceramic article is from 0.14 to 0.25 g/cc.

12. The low-density resin impregnated ceramic article as in claim 1, wherein said ceramic article is a structural ceramic ablator.