In a fairly recent dispatch, now accessible on the West Virginia Coal Association's web site via the link:
we made report of:
"United States Patent 6,656,238 - Coal-based Carbon Foam; 2003; Inventors: Darren Rogers and Janusz Wladyslaw, Wheeling and Glen Dale, WV; Assignee: Touchstone Research Lab, Triadelphia, WV; Abstract: A method for the manufacture of coal-based carbon foams from a coal particulate starting material that comprises blending from 1 to about 10% by weight of pitch with the coal particulate before foaming";
which details how rigid Carbon foams, of consistent structure and properties, and similar in some respects to rigid polyurethane or other plastic foams, can be made out of Coal.
In that report, we also included separate reference to the U.S. Army Forces Strategic Command's report of:
"'Coal-Based Carbon Foam'; Coal-based carbon foam is an enabling technology critical to improving the performance of a wide variety of next-generation material systems and components. Coal-based carbon foams are a new structural material made in a cost-effective proprietary process. Coal-based carbon foams will help to enhance capabilities and improve affordability, supporting today’s warfighter. Applications for coal-based carbon foams continue to be developed as the material is accepted as a mainstream structural building block for tomorrow’s technology. Current application examples include targeted advances in composite tooling, vehicle blast mitigation, radar absorption, and ablation panels";
which explained one value of such Coal-based Carbon foam, at least in terms of military endeavor.
And, herein, via excerpts from the initial and one following link in this dispatch, we further document both the technology for making such versatile and valuable, extreme-performance, structural foam from our abundant Coal; and, the fact that the properties of such Coal-based foam make it valuable in some key military applications, a fact which has been further recognized and acknowledged by the United States defense establishment:
"United States Patent 6,749,652 - Cellular Coal Products and Processes
Date: June, 2004
Inventor: Darren Rogers, Wheeling, WV
Assignee: Touchstone Research Laboratory, Triadelphia, WV
Abstract: According to the present invention there is provided a porous coal-based material having a density of between about 0.1 g/cm3 and about 0.6 g/cm3 that is produced by the controlled heating of small coal particulate in a "mold" and under a non-oxidizing atmosphere. The coal starting material preferably exhibits a free swell index of between about 3.5 and about 5.0 and most preferably between about 4.0 and about 4.5. The porous product thereby produced can be machined, adhered and otherwise fabricated to produce a wide variety of low cost, low density products, or used in its preformed shape as a filter, heat or electrical insulator etc. Such porous products, without further treatment exhibit compressive strengths of up to about 6000 psi. Further treatment by carbonization or graphitization yields products that can be used as electrical or heat conductors. Methods for the production of these coal-based cellular products are also described.
Government Interests: The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license other on reasonable terms as provided for by the terms of contract no. N00014-00-C-0062 awarded by Office of Naval Research.
Claims: A green carbon foam produced by heating comminuted swelling coal particles in a mold under a non-oxidizing atmosphere, the atmosphere having a pressure ranging from about 50 psi to about 500 psi, and to a temperature ranging from about 300 C to about 700 C.
The method ... further comprising the step of calcining the carbon foam by heating the carbon foam to a temperature ranging from about 800 C to about 1200 C to produce calcined carbon foam.
A method of making green carbon foam, comprising the steps of: placing swelling bituminous coal particles in a mold; heating the swelling bituminous coal particles under a non-oxidizing atmosphere to a first temperature; and controlling pressure of the non-oxidizing atmosphere in the mold, wherein the pressure is maintained from about 50 psi to about 500 psi, wherein the steps of controlling pressure and heating the bituminous coal particles produces green carbon foam.
The method ... further comprising the step of graphitizing the carbon foam by heating the carbon foam to a temperature ranging from about 1700 C to about 3000 C to produce graphitized carbon foam.
The method ... further comprising the step of calcining the carbon foam by heating the carbon foam to a temperature ranging from about 800 C to about 1200 C to produce calcined carbon foam.
A method of making green carbon foam, comprising the steps of: placing swelling bituminous coal particles in a mold; heating the swelling bituminous coal particles under a non-oxidizing atmosphere to a first temperature; and controlling pressure of the non-oxidizing atmosphere in the mold, wherein the pressure is maintained from about 50 psi to about 500 psi, wherein the steps of controlling pressure and heating the bituminous coal particles produces green carbon foam.
The method ... further comprising the step of graphitizing the carbon foam by heating the carbon foam to a temperature ranging from about 1700 C to about 3000 C to produce graphitized carbon foam.
Background and Field: The present invention relates to cellular coal products produced from coal powder and to their methods of production. Products utilizing the coal-based porous products are also described.
ASTM standards DD5515-97, "Standard Test Method for the Determination of Swelling Properties of Bituminous Coal" and D720-91 "Standard Test Method for Free Swelling Index of Coal" both define conditions for measuring the inherent property of coals to "swell" upon heating in an uncontrolled combustion situation. Hence, the propensity of coal to swell is well known in the prior art. To the best of our knowledge, however, no one has attempted to take advantage of this property of coals to swell by controllably "swelling" a coal product to obtain a highly useful, low density, porous carbon product.
Similarly, very sophisticated processes have been developed for the production of cellular foamed carbon products. Such processes often involve the use of blowing agents and the application of very high pressures in the fabrication process, and many use highly sophisticated starting materials. These materials, while very lightweight and demonstrating superior strength, tend to be relatively costly, either due to the nature of their starting materials and/or the complexity of their fabrication processes.
There exists a wide and varied class of requirements for low-density materials in the construction, aerospace, transportation, metal processing and other industries for which low-density materials are constantly being developed. Many of these materials exhibit properties such as fire resistance that make them uniquely suited to their end use application. In many applications, however, the aforementioned relatively high cost, low-density materials cannot be used because the final application will simply not justify their relatively high cost.
Accordingly, it would be most desirable if a relatively low cost, low-density material demonstrating many of the desirable characteristics of the aforementioned products, such as fire resistance, were available.
It is therefore an object of the present invention to provide a relatively low cost, low density product that is suited to application in the construction, aerospace, transportation, metal processing and other industries where such properties are desired.
Summary: According to the present invention there are provided coal-based cellular or porous products having a density of preferably between about 0.1 g/cm3 and about 0.8 g/cm3 that are produced by the controlled heating of coal particulate preferably up to 1/4 inch in diameter in a "mold" and under a non-oxidizing atmosphere. According to a specifically preferred embodiment, the starting material coal has a free swell index as determined by aforementioned ASTM D720 test of between about 3.5 and about 5.0. The porous product thereby produced, preferably as a net shape or near net shape, can be machined, adhered and otherwise fabricated to produce a wide variety of low cost, low density products, or used in its preformed shape as a filter, heat or electrical insulator etc. Such cellular products, without further treatment and/or the addition of strengthening additives have been shown to exhibit compressive strengths of up to about 4000 psi. Impregnation with appropriate materials or the incorporation of various strength improving additives can further increase the compressive, tensile and other properties of these cellular materials. Further treatment by carbonization or graphitization yields cellular products that can be used as electrical or beat conductors.
The starting material coal may include bitumen, anthracite, or even lignite, or blends of these coals that exhibit a "free swell index" as determined by ASTM D720 of between about 3.5 and about 5.0, but are preferably bituminous, agglomerating coals that have been comminuted to an appropriate particle size, preferably to a fine powder below about -60 to -80 mesh.
The cellular coal-based products described herein are ... largely isotropic i.e., demonstrating physical properties that are approximately equal in all directions.
ASTM standards DD5515-97, "Standard Test Method for the Determination of Swelling Properties of Bituminous Coal" and D720-91 "Standard Test Method for Free Swelling Index of Coal" both define conditions for measuring the inherent property of coals to "swell" upon heating in an uncontrolled combustion situation. Hence, the propensity of coal to swell is well known in the prior art. To the best of our knowledge, however, no one has attempted to take advantage of this property of coals to swell by controllably "swelling" a coal product to obtain a highly useful, low density, porous carbon product.
Similarly, very sophisticated processes have been developed for the production of cellular foamed carbon products. Such processes often involve the use of blowing agents and the application of very high pressures in the fabrication process, and many use highly sophisticated starting materials. These materials, while very lightweight and demonstrating superior strength, tend to be relatively costly, either due to the nature of their starting materials and/or the complexity of their fabrication processes.
There exists a wide and varied class of requirements for low-density materials in the construction, aerospace, transportation, metal processing and other industries for which low-density materials are constantly being developed. Many of these materials exhibit properties such as fire resistance that make them uniquely suited to their end use application. In many applications, however, the aforementioned relatively high cost, low-density materials cannot be used because the final application will simply not justify their relatively high cost.
Accordingly, it would be most desirable if a relatively low cost, low-density material demonstrating many of the desirable characteristics of the aforementioned products, such as fire resistance, were available.
It is therefore an object of the present invention to provide a relatively low cost, low density product that is suited to application in the construction, aerospace, transportation, metal processing and other industries where such properties are desired.
Summary: According to the present invention there are provided coal-based cellular or porous products having a density of preferably between about 0.1 g/cm3 and about 0.8 g/cm3 that are produced by the controlled heating of coal particulate preferably up to 1/4 inch in diameter in a "mold" and under a non-oxidizing atmosphere. According to a specifically preferred embodiment, the starting material coal has a free swell index as determined by aforementioned ASTM D720 test of between about 3.5 and about 5.0. The porous product thereby produced, preferably as a net shape or near net shape, can be machined, adhered and otherwise fabricated to produce a wide variety of low cost, low density products, or used in its preformed shape as a filter, heat or electrical insulator etc. Such cellular products, without further treatment and/or the addition of strengthening additives have been shown to exhibit compressive strengths of up to about 4000 psi. Impregnation with appropriate materials or the incorporation of various strength improving additives can further increase the compressive, tensile and other properties of these cellular materials. Further treatment by carbonization or graphitization yields cellular products that can be used as electrical or beat conductors.
The starting material coal may include bitumen, anthracite, or even lignite, or blends of these coals that exhibit a "free swell index" as determined by ASTM D720 of between about 3.5 and about 5.0, but are preferably bituminous, agglomerating coals that have been comminuted to an appropriate particle size, preferably to a fine powder below about -60 to -80 mesh.
The cellular coal-based products described herein are ... largely isotropic i.e., demonstrating physical properties that are approximately equal in all directions.
Typically, the cellular coal-based products of the present invention demonstrate compressive strengths on the order of from about 2000 to about 6000 psi at densities of from about 0.4 to about 0.5 g/cm3.
The production method of the present invention comprises:
1) heating a coal particulate of preferably small i.e., less than about 1/4 inch particle size in a "mold" and under a non-oxidizing atmosphere at a heat up rate of from about 1 to about 20 C to a temperature of between about 300 and about 700 C;
2) soaking at a temperature of between about 300 and 700 C for from about 10 minutes up to about 12 hours to form a preform or finished product; and
3) controllably cooling the preform or finished product to a temperature below about 100 C.
The non-oxidizing atmosphere may be provided by the introduction of inert or non-oxidizing gas into the "mold" at a pressure of from about 0 psi, i.e., free flowing gas, up to about 500 psi. The inert gas used may be any of the commonly used inert or non-oxidizing gases such as ... CO2 ... .
It is generally not desirable that the reaction chamber be vented or leak during the heating and soaking operation. The pressure of the chamber and the increasing volatile content therein tends to retard further volatilization while the cellular product sinters at the indicated elevated temperatures. If the furnace is vented or leaks during soaking, an insufficient amount of volatile matter may be present to permit inter-particle sintering of the coal particles thus resulting in the formation of a sintered powder as opposed to the desired cellular product. Thus, according to a preferred embodiment of the present process, venting or leakage of non-oxidizing gas and generated volatiles is inhibited consistent with the production of an acceptable cellular product.
After expanding the coal particulate (as described) the porous coal product is an open celled material. Several techniques have been developed for "sealing" the surface of the open celled structure to improve its adhesive capabilities for further fabrication and assembly of a number of parts. For example, a layer of a commercially available graphitic adhesive can be coated onto the surface and cured at elevated temperature or allowed to cure at room temperature to provide an adherent skin. Alternatively, the expansion operation can be modified by cooling the expanded coal product or preform rapidly (as specified). It has been discovered that this process modification results in the formation of a more dense skin on the preform or product which presents a closed pore surface to the outside of the preform or product. At these cooling rates, care must be exercised to avoid cracking of the preform or product.
After expanding, the porous coal-based preform or product is readily machineable, sawable and otherwise readily fabricated using conventional fabrication techniques.
Subsequent to production of the preform or product as just described, the preform or product may be subjected to carbonization and/or graphitization according to conventional processes to obtain particular properties desirable for specific applications of the type described hereinafter. Ozonation may also be performed, if activation of the coal-based expanded product would be useful in a final product application such as in filtering of air. Additionally, a variety of additives and structural reinforcers may be added to the coal-based preforms or products either before or after expansion to enhance specific mechanical properties such as fracture strain, fracture toughness and impact resistance. For example, particles, whiskers, fibers, plates, etc. of appropriate carbonaceous or ceramic composition can be incorporated into the porous coal-based preform or product to enhance its mechanical properties.
The open celled, coal-based preforms or products of the present invention can additionally be impregnated with, for example, petroleum pitch, epoxy resins or other polymers using a vacuum assisted resin transfer type of process. The incorporation of such additives provides load transfer advantages similar to those demonstrated in carbon composite materials. In effect a 3-D composite is produced that demonstrates enhanced impact resistance and load transfer properties.
Perhaps the simplest products that could be fabricated using the coal-based porous preforms or products of the present invention are various lightweight sheet products useful in the construction industry. Such products may involve the lamination of various facing materials to the surface of a planar sheet of the preform material using an appropriate adhesive. For example, a very light and relatively inexpensive wall board would simply have paper laminated to its opposing planar surfaces, while a more sophisticated curtain wall product might have aluminum sheet, polymer or fiber-reinforced polymer sheets or even stainless steel sheet laminated thereto. A wide variety of such products that have lightweight, low cost and adequate strength can easily be envisioned for wallboard, structural wallboard, bulkheads, etc. The materials of the present invention exhibit sound insulation and vibration resistance due to excellent sound and vibration damping properties, good thermal insulating properties (less than about 1 watt per meter K thermal conductivity).
Yet other product applications for the materials of the present invention reside in the field of heat exchangers. In this application, the heat transfer properties of a graphitized porous coal-based material can be exploited to produce a heat exchanger capable of extracting heat from or adding heat to a fluid (gas or liquid) flowing through porous coal pores. In this case, the coal-based porous product is joined to an appropriate heat transfer mechanism such as an aluminum skin.
(Relatively) minor process modifications can be envisioned to fabricate the carbon foams of the present invention in injection molding, casting and other similar conventional material fabrication processes."
It is generally not desirable that the reaction chamber be vented or leak during the heating and soaking operation. The pressure of the chamber and the increasing volatile content therein tends to retard further volatilization while the cellular product sinters at the indicated elevated temperatures. If the furnace is vented or leaks during soaking, an insufficient amount of volatile matter may be present to permit inter-particle sintering of the coal particles thus resulting in the formation of a sintered powder as opposed to the desired cellular product. Thus, according to a preferred embodiment of the present process, venting or leakage of non-oxidizing gas and generated volatiles is inhibited consistent with the production of an acceptable cellular product.
After expanding the coal particulate (as described) the porous coal product is an open celled material. Several techniques have been developed for "sealing" the surface of the open celled structure to improve its adhesive capabilities for further fabrication and assembly of a number of parts. For example, a layer of a commercially available graphitic adhesive can be coated onto the surface and cured at elevated temperature or allowed to cure at room temperature to provide an adherent skin. Alternatively, the expansion operation can be modified by cooling the expanded coal product or preform rapidly (as specified). It has been discovered that this process modification results in the formation of a more dense skin on the preform or product which presents a closed pore surface to the outside of the preform or product. At these cooling rates, care must be exercised to avoid cracking of the preform or product.
After expanding, the porous coal-based preform or product is readily machineable, sawable and otherwise readily fabricated using conventional fabrication techniques.
Subsequent to production of the preform or product as just described, the preform or product may be subjected to carbonization and/or graphitization according to conventional processes to obtain particular properties desirable for specific applications of the type described hereinafter. Ozonation may also be performed, if activation of the coal-based expanded product would be useful in a final product application such as in filtering of air. Additionally, a variety of additives and structural reinforcers may be added to the coal-based preforms or products either before or after expansion to enhance specific mechanical properties such as fracture strain, fracture toughness and impact resistance. For example, particles, whiskers, fibers, plates, etc. of appropriate carbonaceous or ceramic composition can be incorporated into the porous coal-based preform or product to enhance its mechanical properties.
The open celled, coal-based preforms or products of the present invention can additionally be impregnated with, for example, petroleum pitch, epoxy resins or other polymers using a vacuum assisted resin transfer type of process. The incorporation of such additives provides load transfer advantages similar to those demonstrated in carbon composite materials. In effect a 3-D composite is produced that demonstrates enhanced impact resistance and load transfer properties.
Perhaps the simplest products that could be fabricated using the coal-based porous preforms or products of the present invention are various lightweight sheet products useful in the construction industry. Such products may involve the lamination of various facing materials to the surface of a planar sheet of the preform material using an appropriate adhesive. For example, a very light and relatively inexpensive wall board would simply have paper laminated to its opposing planar surfaces, while a more sophisticated curtain wall product might have aluminum sheet, polymer or fiber-reinforced polymer sheets or even stainless steel sheet laminated thereto. A wide variety of such products that have lightweight, low cost and adequate strength can easily be envisioned for wallboard, structural wallboard, bulkheads, etc. The materials of the present invention exhibit sound insulation and vibration resistance due to excellent sound and vibration damping properties, good thermal insulating properties (less than about 1 watt per meter K thermal conductivity).
Yet other product applications for the materials of the present invention reside in the field of heat exchangers. In this application, the heat transfer properties of a graphitized porous coal-based material can be exploited to produce a heat exchanger capable of extracting heat from or adding heat to a fluid (gas or liquid) flowing through porous coal pores. In this case, the coal-based porous product is joined to an appropriate heat transfer mechanism such as an aluminum skin.
(Relatively) minor process modifications can be envisioned to fabricate the carbon foams of the present invention in injection molding, casting and other similar conventional material fabrication processes."
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We've likely included more technicalities of Touchstone Research Laboratory's Coal foam process than are necessary, or likely wanted by the majority of our readers; but, we assure you, the full Disclosure is even more detailed. We, here, remain a tad uncertain as to why the United States Navy was interested in such a process, unless it centers on the ability to form lighter-weight structural composites with enhanced resistance to vibration, better sound deadening, etc., since, unlike the US Army's exposition, as cited above, no mention is made of Coal foam's utility as impact-absorbing armor.
As a hopefully semi-interesting aside, Graphite, as can be made herein from Coal, has had, as seen in:
Graphite - Wikipedia, the free encyclopedia; "During the reign of Elizabeth 1 (1533–1603), ... graphite was used as a refractory material to line molds for cannon balls, resulting in rounder, smoother balls that could be fired farther, contributing to the strength of the English navy";
over the centuries, at least some interesting navy-related applications.
Our Navy remained interested, however, and financed even further improvements on the technology. As seen in excerpts from the following link to:
"United States Patent: 6814765 - Cellular Coal Products and Processes
Date: November, 2004
Inventor: Darren Rogers, Wheeling, WV
Assignee: Touchstone Research Laboratory
Abstract: According to the present invention there is provided a coal-based carbon foam (as specified) that is produced by the controlled heating of high volatile bituminous coal particulate in a "mold" and under a non-oxidizing atmosphere. The high volatile bituminous coal starting material preferably exhibits a free swell index of between about 3.5 and about 5.0 and most preferably between about 3.75 and about 4.5. A number of additional highly desirable characteristics of the high volatile bituminous coal starting material are also described. The carbon foam product thereby produced can be machined, adhered and otherwise fabricated to produce a wide variety of low cost, low density products, or used in its preformed shape as a filter, heat or electrical insulator etc. Such carbon foams, with treatment exhibit compressive strengths of up to about 6000 psi. Further treatment by carbonization or graphitization yields products that can be used as electrical or heat conductors. Methods for the production of these coal-based cellular products are also described.
Government Interests: The U.S. Government has a paid-up license in this invention and the rights in limited circumstances to require the patent owner to license other on reasonable terms as provided for by the terms of contract no. N000 14-00-C-0062 awarded by the Office of Naval Research.
Claims: A green carbon foam comprising: an open-celled structure produced by heating high volatile bituminous coal particles in a pressure controlled reactor above about 300 C, under a pressurized non-oxidizing atmosphere having a pressure from about 50 to about 500 psi, wherein said carbon foam has a density ranging from about 0.1 to about 0.8 g/cm3.
The carbon foam ... having a compressive strength below about 6000 psi (and) that has been further carbonized (and/or) graphitized.
A laminated sheet comprising: a green carbon foam core having a surface, wherein said carbon foam is produced from particulate high volatile bituminous coal and has a density ranging from about 0.1 to about 0.8 g/cm3; and a sheet laminated to said carbon foam surface.
The laminated sheet ... wherein said sheet comprises a material selected from the group consisting of aluminum, steel, polymer sheet, inconel, titanium, refractory metals, fiber reinforced polymer sheet and paper (and) wherein said carbon foam core has been further carbonized.
The laminated sheet ... wherein said carbon foam core is graphitized.
The carbon foam ... having a compressive strength below about 6000 psi (and) that has been further carbonized (and/or) graphitized.
A laminated sheet comprising: a green carbon foam core having a surface, wherein said carbon foam is produced from particulate high volatile bituminous coal and has a density ranging from about 0.1 to about 0.8 g/cm3; and a sheet laminated to said carbon foam surface.
The laminated sheet ... wherein said sheet comprises a material selected from the group consisting of aluminum, steel, polymer sheet, inconel, titanium, refractory metals, fiber reinforced polymer sheet and paper (and) wherein said carbon foam core has been further carbonized.
The laminated sheet ... wherein said carbon foam core is graphitized.
(The Claims go on at some length specifying the volatile and inert matter contents, and other characteristics, of the bituminous Coal to be used, but nowhere gives specific examples concerning source seams or locations. We, here, have no way of knowing what particular Coal would be most appropriate.)
Background and Field: The present invention relates to cellular coal products produced from coal ... and to their methods of production. Products utilizing the coal-based porous products are also described.
(Very) sophisticated processes have been developed for the production of cellular foamed carbon products. Such processes often involve the use of blowing agents and the application of very high pressures in the fabrication process, and many use highly sophisticated starting materials. These materials, while very lightweight and demonstrating superior strength, tend to be relatively costly, either due to the nature of their starting materials and/or the complexity of their fabrication processes.
(It) would be most desirable if a relatively low cost, low-density material demonstrating many of the desirable characteristics ... such as fire resistance, were available.
(Very) sophisticated processes have been developed for the production of cellular foamed carbon products. Such processes often involve the use of blowing agents and the application of very high pressures in the fabrication process, and many use highly sophisticated starting materials. These materials, while very lightweight and demonstrating superior strength, tend to be relatively costly, either due to the nature of their starting materials and/or the complexity of their fabrication processes.
(It) would be most desirable if a relatively low cost, low-density material demonstrating many of the desirable characteristics ... such as fire resistance, were available.
Objects and Summary: It is therefore an object of the present invention to provide a relatively low cost, low density product that is suited to application in the construction, aerospace, transportation, metal processing and other industries where such properties (as described above) are desired.
It is another object of the present invention to provide a simple and low cost method for the production of such products.
According to the present invention there are provided coal-based cellular or porous products, also referred to herein as "carbon foams", having a density (as specified) that are produced by the controlled beating of coal particulate preferably up to 1/2 inch in diameter in a "mold" and under a non-oxidizing atmosphere.
It is another object of the present invention to provide a simple and low cost method for the production of such products.
According to the present invention there are provided coal-based cellular or porous products, also referred to herein as "carbon foams", having a density (as specified) that are produced by the controlled beating of coal particulate preferably up to 1/2 inch in diameter in a "mold" and under a non-oxidizing atmosphere.
The porous product or carbon foams thus produced, preferably as a net shape or near net shape, can be machined, adhered and otherwise fabricated to produce a wide variety of low cost, low density products, or used in its preformed shape as a filter, heat or electrical insulator etc. Such cellular products, without further treatment and/or the addition of strengthening additives have been shown to exhibit compressive strengths of up to about 4000 psi. at densities of between about 0.3 and about 0.4 g/cm3 or 19 to 25 pounds per cubic foot.
Other interesting properties of such materials are tensile strengths of between about 300 and 1000 psi, shear strengths in the range of about 300 psi and impact resistances of between about 0.3 and 0.4 ft-lbs./in2 as measured by Izod impact on a notched, 0.5 square inch cross-section sample. Impregnation with appropriate materials or the incorporation of various strength improving additives can further increase the compressive, tensile and other properties of these cellular materials. Treatment by carbonization or graphitization yields cellular products that can be used as electrical or heat conductors.
The open celled, coal-based preforms or products, i.e. carbon foams, of the present invention can additionally be impregnated with, for example, petroleum pitch, epoxy resins or other polymers using a vacuum assisted resin transfer type of process. The incorporation of such additives provides load transfer advantages similar to those demonstrated in carbon composite materials. In effect a 3-D composite is produced that demonstrates enhanced impact resistance and load transfer properties.
Cellular coal-based extrudate may have virtually any solid shape ranging from a large flat panel 4' (by).8' as might be used as the core of the above-described building panel to square shapes, rounds, channels and even tubular shapes if a bridge die is used in the extrusion process. Almost any shape that can be achieved with plastic or metal extrusion can be similarly obtained using the process of the present invention."
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We remain somewhat puzzled as to the Navy's true interest in such Coal-based cellular Carbon, although the full Disclosures, not reflected in our excerpts, explain that the product can be used in such things as filters and heat exchangers, so there might be especially suitable applications in ship propulsion systems.
However, there are a number of building products described, such as the laminated, standard-size 4 by 8 "building panel", that, as noted in the full Disclosure, would have both insulating and, with additives, some fire-resistance capacities.
Further: Impregnating shaped Coal foam articles with "epoxy resins or other polymers", as indicated, would provide "enhanced impact resistance and load transfer properties".
There are, however, even additional potentials. Touchstone went on, after the Navy funding, to independently develop even more Coal foam manufacturing technologies, with an expanded base of potential applications.
We'll document some of those in coming reports; but, the key thing to keep in mind is that there are a wide variety of plastic, structural and semi-structural, foam materials currently used in many high-volume commercial applications.
And, most of those products rely, at least in part, on petroleum-based raw materials.
Herein, we see yet another opportunity to further develop the potentials of our most abundant domestic fossil resource, Coal, to shake even looser the chains that bind us to the alien powers of OPEC.
Far past time we started paying a little more attention to those potentials, ain't it?