Electric heating – Heating devices – With heating unit structure
Reexamination Certificate
2002-03-13
2003-12-09
Walberg, Teresa (Department: 3742)
Electric heating
Heating devices
With heating unit structure
C219S548000, C219S553000, C338S210000, C427S228000, C427S122000
Reexamination Certificate
active
06660978
ABSTRACT:
TECHNICAL FIELD
The invention relates to the electrothermal field, and in particular to resistive heating elements based on a glass-fibre textile with a pyrocarbon coating and may be used for the production of heating elements in heaters for both industrial and domestic applications.
Russian Patent No. 2018492, 1992 discloses the electrically conducting materials on the basis of woven siliceous or quartz monofilaments with pyrocarbon coatings. Said coating has a width of 2 to 200 nm, and Russian Patent No. 2100914, 1996 discloses the same with a coating of pyrocarbon on the laminated structure.
However in order to obtain the known electrically conducting materials only the highly siliceous or quartz filaments with high softening temperatures could be used. This limits significantly the areas of application for the known materials as heating elements due to their high cost.
U.S. Pat. No. 4,825,049, 1989 discloses an electrically conducting textile consisting of glass-fibre with a pyrolytic carbon coating containing at least 70% of carbon, obtained via pyrolysis of hydrocarbons at temperatures of 800 to 1200° C., with the following ratio of the components, % weight:
Pyrolytic carbon coating
0.001-17.0
Glass-fibre textile
83.0-99.999
The known electrically conducting cloth has a resistance of 0.1 to 1000 Ohm/cm
2
.
Among the disadvantages of the known textile the following could be named: the impossibility of increasing its resistance above 1000 Ohms, which limits its field of application. Besides, the necessity to use the glass-fibre textile with softening temperature over 800° C. because of the high pyrolysis temperature also limits its field of application in various heaters because of is high cost.
Russian Patent No. 2018492, 37/00, 1992 discloses a method of production of electrically conducting materials on the basis of siliceous and quartz filaments coated with pyrocarbon layer involving the deposition of pyrocarbon out of the chemical vapor, achieved at temperature of 800 to 1000° C. out of natural gas.
Russian Patent No. 2100914, 1996 discloses a method of production of electrically conducting elements on the basis of siliceous or quartz monofilaments covered with a layer of pyrocarbon of laminated structure, involving the supply of a hydrocarbon raw material, e.g.—deoxidized white-spirit or kerosene in a flow of inert gas, nitrogen and glass filaments into the reactor with the subsequent deposition of the pyrocarbon out of the chemical vapour to the filaments' surface at the temperature of 100-1100° C.
SUMMARY OF THE INVENTION
The disadvantage of the known methods is the high temperature of the pyrocarbon deposition which results in impossibility of using the glass filaments with low softening temperatures in the production of electrically conducting textiles.
The purpose of the present invention is to obtain the electrically conducting textile with the wide range of resistance as d broadening its field of application at the heating element, as well as the lowering of the temperature of the pyrocarbon deposition in order to increase the range of the glass-fibre textiles used for its production while retaining the low resistance scatter along the whole field.
The purpose is attained via the following: the known electrically conducting textile consisting of glass-fibre textile with the pyrolytic carbon coating is modified to contain a glass-fibre textile with a softening temperature not less than 640° C. and with the pyrocarbon having a paracrystalline structure with a density of 0.9-1.5 g/cm
3
, containing up to 2% weight of hydrogen with the following components ration, % weight:
Pyrocarbon of turbostrate structure
0.2-15.0
Glass-fibre textile with softening temperature at least 650° C.
85.0-99.8
Besides, the electrically conducting cloth may additionally contain the protective polymer coating.
The purpose is also attained via the following: the known method of producing the electrically conducting textile on the basis of the glass filaments coated with the pyrocarbon layer, involving the supply of the raw hydrocarbon material into the reactor in the flow of the inert gas and the subsequent deposition of pyrocarbon out of the chemical vapor in the filaments' surface at high temperature, is modified so that the raw hydrocarbon material used comprises hydrocarbon oils with a viscosity of 5 to 23 cSt, (centistones) which are preliminarily heated to 350-450° C. and in the flow of the inert gas are put through the nozzle with the developed surface at the temperature of 450-550° C., while the deposition of the pyrocarbon out of the chemical vapour is effected at 600-800° C., on the surface of the glass-fibre with the softening temperature at least 640° C. with the subsequent treatment at 350-450° C. in the vacuum.
Besides, the industrial, motor, transformer and vacuum oils are used as oils, and as nozzle the macroporous silica, stainless steel shavings and non-organic filaments are used. It is wise to coat the obtained textile with the protective polymer layer, where the India rubber is used as polymer.
A main advantage of the proposed electrically conducting textile is that it could be produced with a wide range of resistance, namely 1 to 3000 Ohm/square, which allows it to be used as a heating element with a broad range of applications from industrial devices for chemical, pharmaceutical and food industry to household appliances and health care.
The stated result is achieved by including into the electrically conducting textile the glass-fibre textile with the softening temperature at least 650° C. and pyrocarbon of turbostrate structure with the above mentioned parameters as well as carrying out the deposition of the pyrocarbon at much lower temperatures of 600 to 800° C. and the technology of the oil preparation. Besides that, the above allows broadening the range of glass-fibre textiles used for its production and to widen the sphere of application for the electrically conducting cloth by making the heating elements with the wide range of electrical properties while retaining their uniformity at the whole field of the textile, simplifying simultaneously the production method in the economic sense by lowering the pyrocarbon deposition temperature.
The proposed electrically conducting textile has a uniform coating of paracrystalline or turbostrate pyrocarbon on each filament which is achieved by the proposed coating technology. The above excludes the possibility of the stratification of the pyrocarbon coating and provides the uniformity of the electrical properties along the whole field of textile because the scattering of the electrical resistance along the length and across the width is within 7-10%. The claimed ration of the components in the electrically conducting textile provides the wide range of the resistance with which it could be produced.
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Avdeev Oleg Valerievich
Genusova Tatiana Nikolayevna
Rumyantsev Vladimir Igorevitch
3C-Carbon and Ceramic Company B.V.
Fuqua Shawntina T.
Handal & Morofsky
Walberg Teresa
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