Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/62605—Treating the starting powders individually or as mixtures
  • C04B35/62645—Thermal treatment of powders or mixtures thereof other than sintering
  • C04B35/6267—Pyrolysis, carbonisation or auto-combustion reactions
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B6/00—Heating by electric, magnetic or electromagnetic fields
  • H05B6/64—Heating using microwaves
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
  • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
  • B29C35/08—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
  • C04B35/52—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbon, e.g. graphite
  • C04B35/522—Graphite
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/62605—Treating the starting powders individually or as mixtures
  • C04B35/62645—Thermal treatment of powders or mixtures thereof other than sintering
  • C04B35/62655—Drying, e.g. freeze-drying, spray-drying, microwave or supercritical drying
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
  • C04B38/0022—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof obtained by a chemical conversion or reaction other than those relating to the setting or hardening of cement-like material or to the formation of a sol or a gel, e.g. by carbonising or pyrolysing preformed cellular materials based on polymers, organo-metallic or organo-silicon precursors
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B6/00—Heating by electric, magnetic or electromagnetic fields
  • H05B6/02—Induction heating
  • H05B6/10—Induction heating apparatus, other than furnaces, for specific applications
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/48—Organic compounds becoming part of a ceramic after heat treatment, e.g. carbonising phenol resins

Definitions

• the present invention relates to the treatment, i.e. carbonization and/or graphitization of carbon foam materials, and more particularly to the use of microwave and induction heating devices to expedite such heating.
• accelerated heat-up of carbon foam materials is achieved through the use of microwave and induction heating devices while the carbon foam is under an inert atmosphere.
• microwave/induction heating acceleration is obtained through the use of microwave/induction heating devices alone or in concert with more conventional radiation or convection based heating devices.
• the methods and apparatus of the present invention permit the relatively rapid heat-up of carbon foam materials particularly in such processes as the carbonization and/or graphitization thereof.
• porous product/carbon foam 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 carbon foams without further treatment and/or the addition of strengthening additives have been shown to exhibit compressive strengths of up to about 4000 psi. Further treatment by carbonization or graphitization yields carbon foams that can be used as electrical or heat conductors.
• the production method described in that U.S. Patent Application comprises: 1) heating a coal particulate of preferably small i.e., less than about l A 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 to yield a "green foam".
• 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 nitrogen, helium, argon, C0 , etc.
• the "green foam” may be subjected to carbonization and/or graphitization according to conventional processes to obtain particular properties desirable for specific applications.
• Carbonization is conventionally performed by heating the "green foam" under an appropriate inert gas at a heat-up rate of less than about 5°C per minute to a temperature of between about 800°C and about 1200°C and soaking for from about 1 hour to about three or more hours.
• Appropriate inert gases are those described above that are tolerant of these high temperatures.
• the inert atmosphere is supplied at a pressure of from about 0 psi up to a few atmospheres.
• the carbonization/calcination process serves to remove substantially all of the non-carbon volatile elements present in the "green foam" such as sulfur, oxygen, hydrogen, etc.
• Graphitization commonly involves heating the "green foam" either before or after carbonization at heat-up rate of less than about 10° C per minute, preferably from about 1° C to about 5° C per minute, to a temperature of between about 1700° C and about 3000° C in an atmosphere of helium or argon and soaking for a period of less than about one hour.
• the inert gas may be supplied at a pressure ranging from about 0 psi up to a few atmospheres.
• Microwave heating units can be advantageous in that they are more energy efficient and heat more uniformly than conventional radiant energy or convection ovens and furnaces.
• Microwave ovens or furnaces generate electromagnetic waves, which cause the molecules of an object contained therein to move and rotate creating intermolecular friction. This friction between molecules results in the internal generation of heat.
• Such "internal” “frictional” heating while, as shown below being more rapid, is also more uniform, since the entire mass being heated tends to increase in temperature at a relatively uniform rate.
• relatively less disparity exists between externally and internally located portions of the mass of the structure being heated.
• Such relatively more uniform heating while leading to more uniform production of properties within the structure of the heated object, also produces less propensity for thermal cracking due to significantly different temperatures being achieved in different portions of the carbon structure during heat up.
• the air or inert gas atmosphere inside the microwave chamber does not heat due to the fact that molecules in a gas are too dispersed to create much friction or absorb much of the electromagnetic energy, hence little if any radiant or convection heating is produced.
• the amount of thermal energy imparted to a sample as a result of the microwaves can be altered varying the power settings by percentages.
• the power setting actually only set the time a microwave heats versus adjusting the actual power. For example, if the power is set on 40%, then the microwave heats for 40% of the time, instead of 40% power.
• Microwave ovens/furnaces are commercially available with adjustable power settings that alter the power delivered to a contained sample and these would be similarly useful and perhaps preferred as with such systems, continuous, uniform heating at a reduced power level is possible.
• green foam i. e. a material produced by the controlled foaming of a coal-based particulate as described hereinabove and in greater detail in U.S. Patent Application Serial No. 09/902,828 (which is incorporated herein by reference in its entirety), is .carbonized and/or graphitized using microwave energy to obtain more rapid and uniform heating thereby reducing the potential for thermal cracking of the carbon foam and significantly shortening the carbonization and/or graphitization processing cycle(s).
• microwave based heating methods of the present invention can be applied alone or in concert with more conventional radiant energy or convection based heating devices.
• microwave heating methods described herein are described primarily in connection with the carbonization/graphitization of carbon foams produced from coal particulate, it should be recognized that these methods are equally applicable to the carbonization/graphitization of carbon foams produced from other starting materials such as petroleum or synthetic pitch as well as carbon foams that are the product of the controlled foaming of blends of coal particulate and petroleum or synthetic pitch.
• the method of the present invention comprises carbonizing and or graphitizing a "green foam" structure, i.e. a carbon foam mass, that has not been subjected to carbonization and/or graphitization under an inert atmosphere using microwave energy to obtain relatively more rapid and uniform heating.
• a "green foam” structure i.e. a carbon foam mass
• the power capability of the microwave device utilized in accordance with the present invention is not particularly critical except that it should be of adequate power capability to achieve heating of the carbon foam structure in a shortened period of time.
• the microwave power applied and the duration and variation of the power application will vary from carbon foam material to carbon foam material and according to the mass, i. e. thickness, density etc. of the carbon foam
• the power parameters are readily determinable by trial and error or experimentation and accordingly can vary widely depending upon the foregoing carbon foam characteristics. As shown in the Examples below, it has been found advantageous to increase the power level as heating occurs. The amount of such power increase is again readily determinable by experimentation.
• Example 1 the "green foam” sample was placed directly into the microwave oven on the turntable thereof.
• Example 2 the sample was placed on a firebrick located upon the oven turntable.
• Example 3 the sample was placed on an oven brick and wrapped in an insulating material.
• Microwaves are thus shown to be very effective in heating carbon foam — capable of bringing a sample to 1000°C in tens of minutes.
• the use of an insulating blanket is desirable in the experimental set up used in these tests because of the necessity for accessing the sample to obtain temperature measurements.
• the location of thermocouples in the sample with access thereto from outside of the microwave device would eliminate the need for the insulating blanket.
• samples In the absence of an inert atmosphere, samples (not reported) tended to oxidize and in some cases burn, thus the need for such an atmosphere.
• microwave heating and convection or radiant heating can also be used under certain circumstances to assure complete and uniform treatment of the green carbon foam.
• induction heating may be similarly applied with similar results as induction heating that involves the introduction of magnetic energy into the green carbon foam structure for purposes of heating the same is similarly useful.
• induction heating devices With induction heating devices the level of power and duration of its application will vary with the specific carbon foam undergoing treatment according to its density, thickness, composition etc., but the appropriate treatment parameters are readily determinable by experimentation.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Physics & Mathematics (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Thermal Sciences (AREA)
• Inorganic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Health & Medical Sciences (AREA)
• Electromagnetism (AREA)
• Dispersion Chemistry (AREA)
• Combustion & Propulsion (AREA)
• Carbon And Carbon Compounds (AREA)
• Environmental & Geological Engineering (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Biomedical Technology (AREA)
• Toxicology (AREA)
• Analytical Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• General Induction Heating (AREA)
• Constitution Of High-Frequency Heating (AREA)
• Ceramic Products (AREA)

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• 2003
  • 2003-02-05 CN CN 03803367 patent/CN1628489A/zh active Pending
  • 2003-02-05 EP EP03715973A patent/EP1481572A4/en not_active Withdrawn
  • 2003-02-05 AU AU2003219705A patent/AU2003219705A1/en not_active Abandoned
  • 2003-02-05 JP JP2003567135A patent/JP2005516883A/ja active Pending
  • 2003-02-05 WO PCT/US2003/003219 patent/WO2003067931A1/en not_active Application Discontinuation
  • 2003-02-05 KR KR1020047012159A patent/KR100979641B1/ko not_active IP Right Cessation

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