Low density ablator compositions
AssigneeMartin Marietta Corporation
InventorEric L. Strauss
Life of this patent
Estimating the term…
Abstract
Two types of highly filled, elastomeric silicone-base abiative compositions whose densities range from about 0.20 g/cc to about 0.30 g/cc. One type is a carbon char forming, high thermal efficiency ablator containing at least 92 percent by volume of low density filler with a total filler-to-resin volumetric ratio of at least 16 to 1. The additives comprise ground cork, silica or glass microspheres, phenolic microballons and silica and/or carbon fibers. The second type is a silica char forming, RF-transparent ablator containing at least 90 percent by volume of low density filler with a total filler-to-resin volumetric ratio of at least 11 to 1. The additives comprise silica or glass microspheres and silica fibers.
Claims46
A low density ablator composition having a density of not greater than 0.25 g/cc for providing ablation protection comprising:
- 100 parts by volume of a siloxane elastomer resin selected from the group consisting of methyl-phenyl-vinyl polysiloxane, dimethyl polysiloxane and methyl-phenyl polysiloxane the viscosity of which is equal to or less than 10,000 centipoise;
- about 1600 to about 1800 parts by volume of a low density filler comprising about 600 to about 900 parts by volume ground cork sized from 0.0165 to 0.0331 inch per 100 parts of resin;
- from about 500 to 800 parts by volume of hollow silica or glass microspheres sized from 0.0030 to 0.0080 inch per 100 parts of resin;
- up to about 260 parts by volume of hollow phenolic resin microballoons sized from 0.0030 to 0.0080 inch per 100 parts of resin;
- up to about 6 parts by volume carbon fibers per 100 parts of resin;
- and, up to about 6 parts by volume of silica fibers per 100 parts of resin.
A method of insulating a structure with an ablator composition comprising the steps of:
- mixing together 100 parts by volume of siloxane resin selected from the group consisting of methyl-phenyl-vinyl polysiloxane, dimethyl polysiloxane and methyl-phenyl polysiloxane the viscosity of which is equal to or less than 10,000centipoise and about 12 parts by volume of fibers selected from the group consisting of silica and carbon fibers and mixtures thereof;
- distributing uniformly in the resin-fiber mixture 500 to 800 parts by volume silica or glass microspheres sized from 0.0030 to 0.0080 inch, from about 600 to about 900 parts by volume ground cork sized from 0.0165 to 0.0331 inch and up to 260 parts by volume of phenolic microballoons sized from 0.0030 to 0.0080 inch;
- forming the resulting mixture into a predetermined configuration between the structure and a region subject to high temperature exposure, and curing the mixture for a time at a temperature sufficient to cure the siloxane resin.
A low density ablator composition having a density not greater than 0.30 g/cc for providing ablation protection comprising:
- 100 parts by volume of a siloxane elastomer resin selected from the group consisting of methyl-phenyl-vinyl polysiloxane, dimethyl polysiloxane and methyl-phenyl polysiloxane the viscosity of which is equal to or less than 10,000 centipoise;
- about 1180 parts by volume of filler comprising about 1175 parts by volume silica or glass microspheres sized from 0.0030 to 0.0080 inch per 100 parts resin;
- and, about 6 parts silica fibers.
A method of insulating a structure with an ablator composition comprising the steps of:
- mixing together 100 parts by weight of siloxane resin selected from the group consisting of methyl-phenyl-vinyl polysiloxane, dimethyl polysiloxane and methyl-phenyl polysiloxane the viscosity of which is equal to or less than 10,000 centipoise and about 5 to 10 parts by volume of silica fibers;
- distributing uniformly in the resin-fiber mixture about 1000 to 1300 parts by volume silica or glass microspheres sized from 0.0030 to 0.0080 inch;
- forming the resulting mixture into a predetermined configuration between the structure and a region subject to high temperature exposure;
- and curing the mixture for a time and at a temperature sufficient to cure the siloxane.
A method of insulating a structure with an ablator composition comprising the steps of:
- mixing together 100 parts by weight of siloxane resin selected from the group consisting of methyl-phenyl-vinyl polysiloxane, dimethyl polysiloxane and methyl-phenyl siloxane and about 6 parts by volume of silica fibers;
- distributing uniformly in the resin-fiber mixture 1175 parts by volume silica or glass microspheres sized from 0.0030 to 0.0080 inch;
- forming the resulting mixture into a predetermined configuration between the structure and a region subject to high temperature exposure;
- and, curing the mixture for a time and at a temperature sufficient to cure the siloxane resin;
- wherein the viscosity of the siloxane resin is equal to or less than about 10,000 centipoise;
- wherein the distributing of the silica or glass microspheres is achieved with low shear mixing equipment;
- and,
- wherein the curing of the mixture takes place at a net pressure of less than about 1 atmosphere.
Dependencies are inferred from the claim text.