US 934988 A
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PROCESS OF MAKING DURABLE CARBON ELECTRODES FOR ELEGTROLYTICAL PURPOSES.
GUSTAV ADOLPI-I, OP AMMENIDORF, AND ALBERT 'PIETZSCH, OF MAG-DEB'URG, GER-- MANY, ASSIGNORS T0 GHEIVIISCHE FABRIK BUCKAU,
0F MAGDEBURG, GERMANY,
esaese- No Drawing.
To all whom 'ii may concern:
Be it known that we, GUST V ADOLPH, of Ammendorf, doctor of philosophy, a subject of the King of Prussia, and whose post-office address is Schachtweg, Ammendorf, near Halle, Prussia, German Em'pire,-and ALBERT PIETzsoH, of Magdeburg, a subject of the King of Saxony, and whose post-ofiice address'is No. 34: Kaiser-Otto-Ring, Magde-- burg, Prussia, German Empire, have invented a new and useful Process of Making object to render such electrodesmore dutrodes is softened to a certain depth. Now' rable or lasting than the carbon-electrodes now in use. I
It is a well-known fact that carbon-electrodes, after having served for some time in electrolyzing aqueous solutions, manifest an increased resistance to the electric current and that, moreover, the surface of such electhis'softened condition of the carbon-electrode, as is well-known to electrolytical experts, facilitates a rapid destructionof the electrode by both chemical and mechanical actions. This softening of the carbonelectrode results from the fact that said electrode does not constitute a perfectly homogeneous body, whereas it is composed of very minute particles which adhere together more or less closely according to thequality of the carbon or graphite used, so that more I or less fine interstices are left between them. If by the action of the current the surface of the carbon becomes somewhat softened or broken up, the contact with each other of the particles forming the surface is correspondingly diminished and consequently their electrically conducting connection with each other and with the inner particles is reduced. From this it results that one side of each of the loosened particles becomes a cathode and its opposite side an anode. This condltion' of the surface region causes chemical decompositionswith the :formation.
of compounds which in their turn act so as Specification of Letters Patent.
Application filed April 27, 1907. Serial No.
Patented Sept. 2%, 1196M). 370,738.
to accelerate the destruction of the carbon with the effect of deepening the broken up portion of the surface thereby causing the entire elect-rode to become rapidly destroyed. All that has been said about carbon-elem trodes holds good for electrodes made from graphite which therefore are true .equivalents of'carbon electrodes in this respect also. For this reason we wish it to be understood that the term carbon-electrode and carbon I as used in the following part of the specification and the annexed claimsshall comprise both electrodes of carbon and electrodes of graphite.
It is the object of our present invention to prevent the formation of. said softened or broken up surface-region of carbon-electrodesto be used for electrolyzing watery solutions and to give such electrodes a high degree of durability throughout their body, so as-to produce carbon-electrodes that are tenacious of life. i
To obtain long-lived carbon-electrodes for electrolyzing watery\solutions our present invention consists in providing for in the.
pores of the carbon or graphite an electrical conductor of the first order'so as to establish a metallic connection between all of the carbon or graphite particles composing the electrode, said conductor of the first order being of such a nature as to resist the chemical action of the product or products formed at the electrode during the electrolytic process. I For instance if the said product "is chlorin, as in.,electro1yzing aqueous solutions of alkaline chlorids, the carbon or graphite is thoroughly impregnated with a solution of platinum chlorid, and after drying the 'im pregnated carbon-or'graphite is heated up to the decomposition-temperature ofplatlnum-chlorid, wherebymetallic platinum is separated out in the pores of the carbon or graphite, the chlorin set free escapin into the atmosphere.- It may be'observe here "that the provision of metallic platinum within the pores of a carbon-electrode cannot be brought about'by electrolytical decomposition for the reason that at once so much platinum is deposited upon and inthe surface region ofv the carbon or graphite treated thatno current-lines can find their way into deeper regions, as may readily be proved by experiment.
We are aware that prior to our present invention attempts have been made to cover carbon-electrodes with conductors of the first order. For instance the pores at and in proximity of the surface of carbon-electrodes have been mechanically filled with a chemically resistant paste in order to protect a metallic rod placed within the carbon-electrode for connecting the same with the source of electricity. In. another instance carbon-electrodes have been coated with an electrolytically produced deposit of platinum to serve as an accumulator for hydrogen, such deposit requiring to be of a porous condition. In all known instances the aim was to improve the surface-region of the carbon electrode or to render it suitable for speeach other by metallic bridges and thereby are hindered from becoming active'as separate local electrodes. It is not absolutely necessary that the pores of the electrode are closely filled up with the conductor of the first order used.
lVhat we claim as our invention is':-
1. The herein described process of making electrolytic electrodes resistant to chemical attack. which comprises impregnating the carbon throughout the entire body of the electrode with an electrical conductor of the first order, forming conducting bridges between the particles of carbon, whereby local electrolytic actions between the particles of the electrode are prevented.
high degree of durability through-' 27 The'herein described process of making electrolytic electrodes resistant to chemical attack which consists in impregnating the carbon throughout the entire body of the electrode with a solution of a compound of an electrical conductor of the first order, and
subsequently treating the impregnated carbon tocause the metallic component of said compound toebecome freed and form conducting bridges between the particles of carbon throughoutthe entire mass, whereby local electrolytic actions between the particles of the electrode are prevented.
3. The herein described process of making electrolytic electrodes resistant to chemical attack which consists in impregnating the carbon throughout-the entire body of the electrode with a solution of a platinum salt and decomposing said solution to form conducting bridges of platinum between the particles of carbon throughout the entire mass, whereby local electrolytic actions between the particles of the electrode are prevented.
4. The herein described process of making electrolytic electrodes resistant to chemical attack which 'consistsin impregnating the carbon throughout the entire body of theelectrode with a solution of platinum chlorid, drying the impregnated carbon and heating the mass up to the decomposing temperature of the platinum chlorid and thereby forming conducting bridges of platinum .between the particles of carbon throughout the entire mass, whereby localelectrolytic actions between the particles of the electrode are prevented.
In testimony whereof we have hereunto set our hands in presence oftwo subscribing witnesses, viz. for both inventors.
GUSTAV ADOLPH. ALBERT PIETZSCH.
WVitnesses CARL LINDEMANN, I GUSTAV EsoHE.