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Publication numberUS3676371 A
Publication typeGrant
Publication dateJul 11, 1972
Filing dateJan 30, 1970
Priority dateJan 30, 1969
Also published asCA922384A, CA922384A1, DE1904408A1, DE1904408B2
Publication numberUS 3676371 A, US 3676371A, US-A-3676371, US3676371 A, US3676371A
InventorsKoziol Konrad, Lippert Wolfgang, Reichelt Bernhard, Zollner Dieter
Original AssigneeConradty Fa C
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
High output electrode with stabilized electric arc
US 3676371 A
Abstract
A high output electrode of carbon or graphite and method of making same, according to which the electrode has incorporated therein a titanium-boron combination with or without carbides, said titanium-boron combination preferably containing at least one of the compounds TiB and TiB2.
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Description  (OCR text may contain errors)

United States Patent Zollner et al. [4 1 July 11, 1972 [54] HIGH OUTPUT ELECTRODE WITH STABILIZED ELECTRIC ARC References Cited [72] Inventors: Dieter Zollner, Erlangen; Konrad Koziol, UNITED STATES PATENTS gz f f gfi 5222 8 3323 fi' g 3,174,872 3/1965 Fisher et al. ..252/507 schwabach a" of Gennany gang 1,024,257 4/1912 Harden ....2s2/s04 3,065,088 11/1962 Janes et al. ..252/504 [73] Assignee: C. Conradty, Numberg, Germany 22 Filed: Jan. 30, 1970 E 222? Drum'mnd [2]] Appl. No; 7,235

[57] ABSTRACT [30] Foreign Ap lication P i rit D t A high output electrode of carbon or graphite and method of making same, according to which the electrode has incor- Jan. 30, Germany ..P o t d th in a tita iun boron ombination o without carbides, said titanium-boron combination preferably containlll ..252/507 ing at least one f the Compounds and '53,, n [58] Field of Search ..252/507, 504, 503 1 Claim, No Drawings The high output operation of electric arc furnaces during which transformer outputs of approximately from 400 to 500 kVA/t are employed require graphite electrodes of high power transmitting ability. The electric conductivity of the graphite material had, similar to the thermal shock resistance and the oxidation resistance, to be adapted to the increasing current densities and temperature loads. This was done by employing oil cokes of ever higher grade and very good graphitizing behavior, of higher graphitizing temperatures and additional pitch impregnation which require an additional fumace process for the ordinary finishing step for a post-coking. All of these steps are expensive and raise the costs of the manufacturing process of the electrode. In addition thereto, the impregnation of the electrode, which is necessary for lowering the specific electric resistance of the graphite material, frequently brings about an increased liability to form tears in the graphite electrode or to decrease the resistance of the electrode to breaking.

Of great importance in this connection for an economic operation of the high output electric arc furnace is an as uniform as possible current withdrawal from the supply network without any special reaction by the network. Due to the operation with relatively short light arc, it is possible to reduce the flickering, but it is not possible completely to eliminate the same. Moreover, when operating the light are at a low voltage and high current intensity, a greater wear of the tip of the electrode takes place than is the case in the reversed instance. Therefore, attempts have been made to cause the arc to burn in a more stable manner by the employment of hollow electrodes with and without the supply of gases stabilizing the arc. These attempts have been successful. This method, however, has the drawback that it requires a drilled or very dense electrode which at any rate is more expensive than the heretofore customary solid electrode. When operating with gases, additional costs are incurred which could not be justified in spite of the metallurgical advantages of this method.

It is, therefore, an object of the present invention to provide means for increasing the electric load of the electrode and for reducing its liability to oxidation, while maintaining its resistance against tears.

It is also an object of the present invention to provide means for stabilizing the light arc in order to eliminate the flickering for all practical purposes.

These and other objects and advantages of the invention will appear more clearly from the following specification.

By the addition of or impregnation with suitable substances during the manufacturing process of the graphite electrode, the finished graphite electrodes will contain titanium borides which will bring about a considerable reduction in the electric resistance of the electrode while increasing the resistance of the electrode against oxidation and while stabilizing the light are when the electrode is being used in the electric arc furnace. The titanium borides may be added already directly to the mixture of the raw material which mixture customarily consists of a granular mixture of oil coke, tar and pitch. The said titanium borides will, while unchanged during the manufacturing process of the electrode, become effective only when the electrode is used in the electric arc furnace.

Two borides of the titanium are known, namely titanium monoboride TiB, and thetitanium diboride TiB In addition thereto, the titanium is able to absorb considerable quantifies of boron in solid solution so that also this type has the advantages inherent to the present invention. A certain proportion of titanium carbide which may form during the graphitizing process at boundary surface reactions of the added particles with the carbon or graphite will have no disturbing or interfering influence. The total content in titanium-boron compounds may amount to 20 percent, but preferably will be from 1 to 8 percent.

The introduction of the borides into the graphite electrode may be effected in difierent ways, namely:

1. By admixing reaction components to the starting material during the finishing process.

2. By impregnating reaction components and introducing the same into the boron electrode prior to graphitizing the latter. The titanium boron compounds will then form during the graphitizing process from a temperature of.

l,300 C. upwards.

3. By admixing titanium borides to the starting mixture. This method may also be applied with the electrodes which are still to be graphitized. This method is particularly advantageous with carbon electrodes which are not to be graphitized as they are employed, for instance, in connection with the are air method (Fugenhobelverfahren). Also in this instance the same problems are encountered as with large electrodes in the electric arc furnace. The extreme high current intensities which are employed with this cutting-blowing-method require increasing electric conductivity and a higher resistance against oxidation. In view of the stabilization of the electric light arc, a more favorable working condition can be obtained.

With the admixture to the completed electrode, titaniumboron-alloys, titanium monoboride and titanium diboride may be employed.

When admixing the reaction components, there exists the possibility of varying the admixture in conformity with the expected or desired reactions. Thus, for instance, TiO and B 0 may be admixed to the electrode raw mixture, and in this instance during the graphitizing process there will be obtained TiO +B O +5 CTiB +5 CO, or 8 C, titanium and B o are added in which instance during the graphitizing process the following reaction is obtained 7Ti+3 B C+B O 7TiB+3 CO. These methods may serve as examples.

The introduction of titanium components and boron components into an already burned electrode may be effected also by impregnation with titanium silicon compounds and boron organic compounds in organic solution with a subsequent dilution of the solution, for instance, by humidification so that a disintegration of such organic compounds will occur. Such disintegration may also be carried out in a purely thermal way.

There may now be set forth two examples for preparing the mixture for an electrode according to the invention.

EXAMPLE I 7% by weight of oil coke with a granular size of from 4 to 8 mm 14% by weight of oil coke with a granular size of from 2 to 4 mm 18% by weight of oil coke with a granular size of from 0.5 to 2 mm 53.5% by weight of oil coke with a granular size of less than 0.5 mm 4% by weight of TiO dust with a granular size of less than 0.1 mm 3.5% by weight of B 0 with a granular size of less than 0.5 mm To the above mentioned dry starting mixture there were added 25 percent by weight of pitch with a softening or fusion point of 82 C.

The thus obtained product was then further processed in a manner customary with the manufacture of carbon or graphite electrodes, i.e., by mixing, pressing, glowing and graphetizing.

EXAMPLE [I 26.5% by weight of oil coke with a granular size of from 4 to 8 232% by weight of oil coke with a granular size of from 2 to 4 3 3% by weight of oil coke with a granular size of from 0.5 to

25 7 by weight of oil coke with a granular size of less than 0.5

57 by weight of TiB, dust with a granular size of less than To the above mentioned starting mixture there was added 23.5 percent by weight of pitch or insulating asphalt with a softening or fusion point of 82 C.

The thus obtained product was then further processed in a manner customary with the manufacture of carbon or graphite electrodes, by mixing, pressing, glowing, and graphetizing, which steps have no harmful effect upon the stabilizing effect of TiO Electrodes produced in conformity with the present invention can absorb a considerably higher electric load, have a higher resistance against oxidation and are characterized by a great stability of the light arc, which is in contrast to normal carbon or graphite electrodes.

It is, of course, to be understood that the present invention is, by no means, limited to the particular examples set forth above but also comprises any modifications within the scope of the appended claims. Thus, while e.g., in Example I TiO, 2 dust with a granular size of less than 0.1 mm has been mentioned, the granular size of TiO, may advantageously be less than 60/],000 mm.

What we claim is:

1. A high output electrode of carbon material, especially carbon electrode and graphite electrode, which includes a titanium-boron combination consisting of at least one of the compounds TiB and TiB of from 1 to 8 percent to thereby improve the oxidation resistance, electrical load ability, and electric arc stability for light are furnace means used in steel making and a remaining part of the electrode amounting to percent and more consists of graphite.

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Patent Citations
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US1024257 *Apr 27, 1905Apr 23, 1912Gbhebai EjcjscElectrode.
US3065088 *Sep 30, 1959Nov 20, 1962Union Carbide CorpOxidation-resistant graphite article and method
US3174872 *Jan 8, 1963Mar 23, 1965Union Carbide CorpOxidation resistant carbon refractory articles
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4161433 *Feb 17, 1978Jul 17, 1979Oronzio De Nora Impianti Elettrochimici S.P.A.Decomposition of alkali metal amalgams
US4376029 *Sep 11, 1980Mar 8, 1983Great Lakes Carbon CorporationTitanium diboride-graphite composits
US4465581 *Jul 27, 1981Aug 14, 1984Great Lakes Carbon CorporationComposite of TiB2 -graphite
US6376977 *May 30, 2000Apr 23, 2002Shin-Etsu Chemical Co., Ltd.Silicon electrode plate
US7264682May 3, 2005Sep 4, 2007University Of Utah Research FoundationTitanium boride coatings on titanium surfaces and associated methods
US7459105Jul 7, 2005Dec 2, 2008University Of Utah Research FoundationNanostructured titanium monoboride monolithic material and associated methods
US7501081Jan 25, 2007Mar 10, 2009University Of Utah Research FoundationNanostructured titanium monoboride monolithic material and associated methods
US7820129 *Sep 16, 2004Oct 26, 2010Sachtleben Chemie GmbhMethod for improving the durability of carbon or graphite electrodes by using Tio2—containing products
US8211278Jul 28, 2010Jul 3, 2012Alcoa Inc.Composition for making wettable cathode in aluminum smelting
US20050208213 *May 3, 2005Sep 22, 2005University Of Utah Research FoundationTitanium boride coatings on titanium surfaces and associated methods
US20070018139 *Jul 7, 2005Jan 25, 2007Chandran K S RNanostructured titanium monoboride monolithic material and associated methods
US20070235701 *Jan 25, 2007Oct 11, 2007Chandran K S RNanostructured titanium monoboride monolithic material and associated methods
US20080048154 *Sep 16, 2004Feb 28, 2008Djamschid Amirzadeh-AslMethod for Improving the Durability of Carbon or Graphite Electrodes by Using Tio2 -Containing Products
US20100176339 *Jan 12, 2009Jul 15, 2010Chandran K S RaviJewelry having titanium boride compounds and methods of making the same
CN102822392A *Mar 29, 2011Dec 12, 2012日本电极株式会社Cathode carbon block for aluminum smelting purposes, and process for production thereof
CN102822392B *Mar 29, 2011Jul 8, 2015日本电极株式会社Cathode carbon block for aluminum smelting purposes, and process for production thereof
EP0084059A1 *Jul 22, 1982Jul 27, 1983Great Lakes Carbon CorporationComposite of tib2-graphite
EP0084059A4 *Jul 22, 1982May 17, 1984Great Lakes Carbon CorpComposite of tib2-graphite.
EP2554715A1 *Mar 29, 2011Feb 6, 2013Nippon Electrode Co., Ltd.Cathode carbon block for aluminum smelting and process for production thereof
EP2554715A4 *Mar 29, 2011Mar 11, 2015Nippon Electrode Co LtdCathode carbon block for aluminum smelting and process for production thereof
WO1982001018A1 *Sep 11, 1981Apr 1, 1982Lakes Carbon Corp GreatTitanium diboride-graphite composites
WO2004046262A2 *Nov 17, 2003Jun 3, 2004University Of UtahIntegral titanium boride coatings on titanium surfaces and associated methods
WO2004046262A3 *Nov 17, 2003Aug 5, 2004Shampa AichIntegral titanium boride coatings on titanium surfaces and associated methods
Classifications
U.S. Classification252/507, 204/294, 204/291
International ClassificationH05B7/00, H05B7/085, C04B35/52
Cooperative ClassificationH05B7/085, C04B35/52
European ClassificationH05B7/085, C04B35/52