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AssigneeThe B. F. Goodrich Company
InventorsLarry D. Bentson, Robert J. Price, Mark J. Purdy, Edward R. Stover
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Carbon/carbon composites including those structures formed from a fibrous reinforcement itself formed principally from carbon in a carbon matrix are protected against oxidation by multi-layer sealant system preferably including a multi-layer paint including in its carbonized binder refactory granules and inhibitor particles that form a moisture resistant, viscosity-stabilized borate glass when exposed to a high-temperature, oxidizing environment, and an outer ceramic shell formed by CVI/CVD in situ formation of boron carbide followed by silicon carbide. The paint is prepared by mixing finely divided powders of borate precursor compounds or borate glass frit and refractory granules with a carbon char yielding precursor binder such as phenolic resin or pitch which preferably produces a highly porous structure upon carbonization.
An oxidization-resistant structure comprising a carbon/carbon substrate formed with interstices throughout, the substrate having in its as-manufactured (carbonized) state prior to substantial exposure in an oxidizing atmosphere at elevated temperatures, a multi-layer oxidation protection system including
An oxidation-resistant structure comprising a carbon/carbon substrate formed with interstices throughout, the substrate having in its as-manufactured state prior to substantial exposure in an oxidizing atmosphere at elevated temperature, a multi-layer oxidation protection system including a sealant layer having refractory granules, boron or boron carbide and at least one compound selected from the group consisting SiO.sub.2, ZrO.sub.2, Li.sub.2 ZrO.sub.3, LiSiO.sub.3 and glass frits, with a molar composition exclusive of the refractory granules when fully oxidized:
An oxidation-resistant structure comprising a carbon/carbon structure formed with interstices throughout, the substrate having in its as-manufactured state prior to substantial exposure in an oxidizing atmosphere at elevated temperature, a multi-layer oxidation protection system including a CVI/CVD layer of boron carbide having a thickness of from about 5 to about 25 micrometers which penetrates the carbon/carbon substrate, the structure further including a sealant layer underlying the CVI/CVD layer of boron carbide, the sealant layer comprising boron, silicon, and zirconium, in elemental form or as an oxide or oxidizable moiety or mixture of any of the foregoing chemical forms, and lithium as an oxide or oxidizable moiety or mixture of the forgoing chemical forms, and refractory granules having a size from about 250 micrometers to about 50 micrometers dispersed in a carbonaceous binder, the boron expressed as boron being present in amount of from about 10 to 50 weight percent, the silicon expressed as silicon dioxide present in amount of from about 0 to 25 weight percent, lithium expressed as lithium oxide (Li.sub.2 O) in amount of from about 0 to about 10 weight percent and zirconium expressed as zirconia in amount from about 0 to about 30 weight percent and refractory granules in amount of about 20 to 80 weight percent, all of the foregoing expressed in percent by weight of the total sealant layer exclusive of the carbonaceous binder, the amount and character of the carbonaceous binder providing from about 20 to 50 volume percent porosity of the sealant layer exclusive of the volume occupied by the refractory particles, said boron silicon, zirconium, and lithium oxidizing when exposed to a high temperature, oxidizing environment to form boron oxide and a metal oxide within the pores of said sealant layer, and at high temperatures stabilizing the viscosity of the molten borate glass which forms and reducing loss of boron due to exposure to moisture.
An oxidation-resistant structure comprising a carbon-carbon substrate formed with interstices throughout, the substrate having in its as-manufactured state prior to substantial exposure in an oxidizing atmosphere at elevated temperatures, a multi-layer oxidation protection system including a sealant layer having refractory granules, boron or boron carbide and at least one compound selected from the group consisting SiO.sub.2, ZrO.sub.2, Li.sub.2 ZrO.sub.3, LiSiO.sub.3 and glass frits, with a molar composition exclusive of the refractory granules when fully oxidized:
An oxidation-resistant structure comprising a carbon/carbon substrate formed with interstices throughout, the substrate having in its as-manufactured state prior to substantial exposure in an oxidizing atmosphere at elevated temperature, a multi-layer oxidation protection system including a CVI/CVD layer of boron carbide having a thickness of from about 5 to about 25 micrometers which penetrates the carbon/carbon substrate, the multi-layer oxidization protection system including a sealant layer adjacent to said substrate having boron or boron carbide, refractory granules having a size from abut 250 micrometers to about 50 micrometers and at least one compound selected from the group consisting of SiO.sub.2, ZrO.sub.2, Li.sub.2 ZrO.sub.3, LiSiO.sub.3 and glass frits dispersed in a carbonaceous binder, with a molar composition when fully oxidized:
Dependencies are inferred from the claim text.