Claims
- 1. A syntactic foam core material adapted to providing a low density reinforced syntactic foam core for composite layered structures comprising
- a layer of hollow ceramic microspheres,
- dry resin powder particles of binder finer in dimension than the diameter of said microspheres thoroughly intermixed in said layer of microspheres to provide a uniform mixture of said powder particles and microspheres,
- said microspheres being a major percentage by volume of said mixture,
- said syntactic foam core material including a honeycomb structure extending through the body of said layer for reinforcement of said layer,
- said mixture of microspheres and resin powder particles having been processed through a cycle of heat softening and setting of said resin particles in interbonded relationship with said microspheres and honeycomb structure,
- said resin particles being present in a quantity to interbond said mixture and said honeycomb structure into an integrated rigid layer,
- said layer having opposite major surfaces for combination with layers of material on opposite sides thereof in layered composite structures.
- 2. A syntactic foam core material as set forth in claim 1 in which said microspheres are glass microspheres.
- 3. A syntactic foam core material as set forth in claim 1 in which said resin powder particles include unexpandable and expandable dry resin binder particles thoroughly intermixed in said mixture,
- said expandable resin binder particles being expandable into microballoons in binding relation with said microspheres and unexpandable powder particles upon heat processing of said resin powder particles.
- 4. A syntactic foam core material as set forth in claim 3 in which said expandable resin particles comprise 6 to 7% by weight of the particles in said mixture.
- 5. A syntactic foam core as set forth in claim 1 in which said microspheres are present in a percentage amount by volume of at least 60% of said mixture.
- 6. A syntactic foam core material as set forth in claim 5 in which the diameter of the microspheres is generally in the order of 170 microns and the size of both said powder particles and expandable resin particles is in the order of 20 microns.
- 7. A syntactic foam core material as set forth in claim 1 in which said honeycomb structure is formed of a base material of cellulose paper.
- 8. A syntactic foam core material as set forth in claim 1 in which said honeycomb structure is formed of one of a group of base materials consisting of fibers of glass, carbon, cellulose and aramid fibers treated with resin.
- 9. A syntactic foam core material set forth in claim 1 in which said honeycomb structure is formed of one of a group of metal base materials consisting of aluminum and copper.
- 10. A syntactic foam core material as set forth in claim 1 in which said resin particles include resin particles which are expandable into microballoons.
- 11. A syntactic foam core material as set forth in claim 1 in which said binder particles comprise 2 to 20% by weight of the particles in said mixture.
- 12. A method of producing a reinforced syntactic foam core material adaptable to incorporation in layered composite structures comprising
- forming a mass of dry particles by combining as parts of said mass a predominant amount by volume of ceramic microspheres and the remainder being dry particles of a first activatable resin binder,
- physically agitating said mass to thoroughly intermix said dry particles into a uniform mixture,
- depositing said uniform mixture as a layer in the cavity of a cavity mold,
- placing a honeycomb structure in said mold cavity over said mixture layer,
- closing said mold to press said honeycomb structure against said mixture layer;
- heating said mixture to heat-soften said resin binder particles for penetration of said mixture into the cells of said structure and establishment of a bonding relation with said microspheres,
- and cooling said heated mixture to set said heat-softened resin particles and interbond said resin particles with said microspheres and honeycomb structure as a core layer.
- 13. A method of producing a syntactic foam core material as set forth in claim 12 in which a catalyst is added in said mass of particles to enhance the adhesion of said resin particles with said microspheres.
- 14. A method of producing a syntactic foam core material according to claim 13 in which said catalyst is coated on said microspheres.
- 15. A method of producing a syntactic foam core material as set forth in claim 12 wherein a second heat activatable resin expandable into microballoons is added as part of said particles of heat activatable resin binder.
- 16. A method of producing a honeycomb reinforced syntactic foam core layer adaptable to incorporation in layered composite structures comprising
- placing a honeycomb structure in the cavity of a cavity mold,
- depositing over said honeycomb structure a layer of dry particles of a syntactic foam mixture predominately of ceramic microspheres and the remainder of dry particles of a heat activatable resin binder,
- said layer including sufficient foam mixture to extend through the cells of said honeycomb structure,
- closing said mold,
- heating said mixture to heat-soften said resin binder particles for penetration of said mixture into the cells of said structure and establishment of a bonding relationship with said microspheres, and
- cooling said heated mixture to set said heat softened resin particles and interbond said resin particles with said microspheres and honeycomb structure as a core layer.
- 17. A method as set forth in claim 16 in which sufficient foam mixture is deposited in said mold cavity to form a layer over said structure in said core layer.
- 18. A method as set forth in claim 16 in which said dry particles of resin binder include resin binder particles expandable into microballoons.
- 19. A method as set forth in claim 16 in which sufficient syntactic foam mixture is deposited over said honeycomb structure which in addition to extending throughout said honeycomb cells will provide a layer of syntactic foam over said honeycomb structure.
- 20. A method as set forth in claim 19 in which a layer of syntactic foam mixture is deposited in said mold before placing said honeycomb structure thereover in said mold.
RELATED APPLICATIONS
This application is a continuation in part of application U.S. Ser. No. 08/600,850 filed Feb. 13, 1996 now allowed, which in turn is a continuation in part of application U.S. Ser. No. 08/282,371 filed Jul. 29, 1994 issued as U.S. Pat. No. 5,587,231 on Dec. 24, 1996.
US Referenced Citations (14)
Continuation in Parts (2)
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Number |
Date |
Country |
Parent |
600850 |
Feb 1996 |
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Parent |
282371 |
Jul 1994 |
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