Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Composite having voids in a component
Reexamination Certificate
1999-01-22
2001-02-06
Cain, Edward J. (Department: 1714)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Composite having voids in a component
Reexamination Certificate
active
06183854
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of making a reinforced carbon foam material having enhanced strength and, more specifically, it relates to such a method which employs selected reinforcing additives which are introduced during the fabrication process. It also relates to the resulting product.
2. Description of the Prior Art
It has long been known that coal has a wide variety of beneficial uses including, for example, use as a fuel in electric utility plants, the production of coke for use in process metallurgy, and the production of a wide variety of carbon products.
In U.S. patent application Ser. No. 08/887,556, entitled “Method or Making a Carbon Foam Material and Resultant Product” filed Jul. 3, 1997 now U.S. Pat. No. 5,888,469, and owned by the assignee of the present application, detailed disclosures are provided for methods of producing anisotropic or isotropic carbon foam having a number of beneficial properties and the resultant product. The disclosure of this application is expressly incorporated herein by reference.
The carbon foam produced by the method disclosed in U.S. patent application Ser. No. 08/887,556 has substantial compressive strength which may be on the order of an excess of about 600 lb/in
2
. It also produces a product which is relatively lightweight and possesses a controllable degree of electrical and thermal conductivity.
In spite of the foregoing known methods and resultant products, there remains a need for a method of making carbon foam and a resultant product which has certain additional desired strength characteristics.
SUMMARY OF THE INVENTION
The present invention has met the above-described needs by providing methods of making anisotropic or isotropic carbon foam material such as in accordance with U.S. Ser. No. 08/887,556 with the introduction during the method of reinforcing additives to the mix to thereby produce enhanced properties such as enhanced tensile strength and modulus.
In a preferred practice of the invention, the reinforcing addition will be carbon nanotubes, carbon nanofibers, chopped graphite fibers, crushed green coke, crushed calcined coke or combinations thereof. It is preferred that the reinforcing additives be included in an amount of about 2 to 8 weight percent of the pitch.
The product produced may be coked to devolatilize and foam, baked, calcined and graphitized, as desired.
It is an object of the present invention to provide an improved carbon foam material and a method of making the same wherein enhanced strength characteristics are provided as the result of the introduction of reinforcing additives during the making of the product.
It is a further object of the present invention to provide reinforcement wherein the reinforcing additives may consist of one or more of a specifically selected group of preferred materials.
It is another object of the present invention to provide such a system wherein known systems of making carbon foam may be employed with only minor modification for the introduction of the reinforcing additives.
It is a further object of the invention to produce a reinforced carbon foam which despite its low density has improved strength and modulus characteristics.
It is yet another object of the present invention to provide such a system wherein properties such as tensile strength, tensile modulus, compressive strength, compressive modulus, flexural strength and flexural modulus are enhanced as a result of the presence of the reinforcing additives.
It is yet another object of the invention to provide such a system wherein the reinforcing additives may be introduced into the materials employed in the method when the materials are in dry form or introduced when the materials are in wet form.
These and other objects of the invention will be more fully understood from the following detailed description of the invention.
REFERENCES:
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patent: 4487687 (1984-12-01), Simo et al.
patent: 4518483 (1985-05-01), Dickakian
U.S. application No. 08/887,556, Stiller.
Wang, Reticulated Vitreous Carbon—A New Versatile Electrode Material, Electrochimica Acta, (1981), pp. 1721-1726, vol. 26, No. 12.
Donnet et al., Carbon Fiber Applications, Carbon Fibers, Marcel Decker, Inc. (1984), pp. 222-261.
Edie et al., Melt Spinning Pitch-Based Carbon Fibers, Carbon, Pergamen Press (1989), pp. 647-655, vol. 27, No. 5.
Wang, Reticulated Vitreous Carbon an Exciting New Material, ERG Energy Research and Generation, Inc., (undated), Oakland, CA.
Pekala et al., Carbon Aerogels and Xerogels, Mat. Res. Soc. Symp. Proc. (1992), pp. 3-14, vol 270.
Hager et al., Idealized Ligament Formation in Geometry in Open-Cell Foams, 21st Biennial Conference on Carbon, Conf. Proceedings, American Carbon Society, (1993), pp. 102-103, Buffalo, NY.
Mehta et al., Graphitic Carbon Foams: Processing and Characterizations, 21st Biennial Conference on Carbon, Conf. Proceedings, American Carbon Society, (1993), pp. 104-105, Buffalo, NY.
Hall et al., Graphitic Foams as Potential Structural Materials, 21st Biennial Conference on Carbon, Conf. Proceedings, American Carbon Society, (1993), pp. 100-101, Buffalo, NY.
Stiller et al., Effects of Additives on the Mechanical Properties of Graphitizable Foams, Proceedings from the 22nd Annual Conference on Ceramic, Metal and Carbon Composites, Materials and Structures, AMPTIAC, (Jan. 1998), pp. 1-10.
Plucinski Januz
Stiller Alfred H.
Yocum Aaron
Cain Edward J.
Eckert Seamans Cherin & Mellott , LLC
Silverman Arnold B.
West Virginia University
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