US1721886A - Electrolytic cell - Google Patents

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July 23, 1929- A. sHuLlMsoN ELECTROLYTIC CELL Filed Sept. 20, 1926 ATTORNEY Patented July 42.3, 1929.

UNITED STATES 1,721,886- P'AITENT OFFICE.

ISRAEL A. SHULIHSON, OF SPRINGFIELD, MASSACHUSETTS, ASSIGNOR TO AMERICAN BOSCH IAGNETO CORPORATION, OF SPRINGFIELD, MASSACHUSETTS, A CORPORA- TION F NEW YORK.

ELECTROLYTIC CELL.

.pplication led September 20, 1926. Serial No. 136,400.

The present invention relates to electro- 'lyt-ic cells for alternating current rectiiers, electrolytic condensers, lightning arresters, and for other purposes,and has particular reference to the chemical composition of the cathodes andthe electrolytes and the anodes of such cells, and to various combinations thereof in such cells, adapted especially for comparatively high voltages and low cur- 'rents as in B battery eliminators for radio circuits or as apart of A, B and C battery eliminators therefor.

y It is Well known that aluminum rectiiies alternating lcurrents in many solutions the most usual of which have been solutions of I found with an aluminum cathode, that a neutral solution of monobasic ammonium phosphate gives a fair degree of rectification and substantially no corrosion.VV Furthermore, this monobasic salt is the most stable of substantially all the phosphates, which highly recommends its use. Upon adding the chromate or dichromate of potassium or am-` monium, the electrolyte becomes acidic and causes corrosion but the degree of the rectification and the voltage output are increased. Furthermore the cromatiJ or dichromate stabilizes the rectifying film and decreases the internal resistance of the cell. n

I also found upon neutralizing this solution, and in fact any of the above noted solutions and also solutions of chromates or dichromates of organic acids br acids with' complex anions, or combinations thereof, that the corrosion isobvi'ated, as a practical matter, at both electrodes, and that the degree of rectification and the voltage output are still furth'ersincreased.A Besides durion, which is extremely brittle and practically unmachinable, a steel or steel alloy or cast iron or lead anode may -be used in this electrolyte, and besides pure aluminum or an aluminum lalloy such vas duraluminum or magnaliurn may be used as the cathode. So also containers of steel or iron or lead may be used.

p Furthermore, I found that a neutral solution of these various salts and combinations thereof may be obtained in various ways. Monobasic phosphate is acidic; dibasic phosphate is alkaline; a mixture can therefore form a neutral solution. Also dichromate is acidic, and with dibasic ammonium phosphate can form a neutral solution. If it is desired. to further increase the number of acidic ingredients, as with oXalic, lactic, tartaric or other acid, the excesses can still be brought back to neutrality with ammonium carbonate. The difficulties of titration may be overcome'by using the ammonium carbonate for neutralization, applying as an indicator the noticeable cessation of the evolution of carbon-dioxide gas upon attaining neutrality. Evenif an excess quantity of ammonium carbonate is use no harmful effect occurs, since ammonium, carbonate is itself a fair rectifying electrolyte with aluminum vand its alloys. y

Furthermore, I found that the addition of such ingredients as lactic acid, or glycerine or invert sugar', or combinations thereof, ive 85 desirable properties due to their colloidal characteristics. For example, glycerine supports a good deal of potential precipitation in a colloid form, which renders it unobjectionable, and it is itself reduced and oxidized in the process of electrolysis. Thus, if for any reason the electrolyte should tend toward acidity or basicity, a compensating oxidation or reduction of the glycerinetends to restore theequilibrium.

In all of the cells, one cathode and one anode may be employed for half Wave rectification, or two cathodes and one anode may be employed for full Wave rectification. Also the container may form `the anode or act v conjointly with an electrode for that purpose if made of the metals above noted.

For a B battery eliminator, I prefer to usean aluminum cathode, a chrome nickel Asteel anode and a steel container, with an electrolyte consisting by Weight of about 15 per "cent monobasic ammonium phosphate, 0.3 per cent potassium dichromate, 6 per cent ammonium carbonate and 1.25 per cent glycerine, in water. For an electrolytlc con- 11o denser, I prefer to reduce the proportions of monobasic ammonium phosphate, the potassium dichromate and the ammonium carbonate to about 2 per cent, 0.2 per cent and L of monobasic ammonium phosphate, 12 grams of potassium dichromate, 24 grams of amciency of rectification is ab ut 90 per cent at.

monium carbonate for neutralizing the solu tion, and4 cem. of gl cerine (approximately 5 grams). A layer o oil 6v is .floated upon the electrolyte to reduce evaporation. The cathode 3 has a rounded end at 7 to prevent erosion from bubble streams during electrolysis and has most of its length covered with a hard rubbers'leeve 8 screwed againsta shoulder as 'shown to present about 2.5 sq. cm. of rectifying surface each and yto prevent disintegrat/ion of the cathodes at the place where the surface of the electrolyte may be at the time.

As shown in Fig. 2, the four cells 9 are arranged in a bridge 'with the terminals of the secondary l0 of a transformer connected to two opposite points thereof and a suitable filter circuit, containing inductances 11 and condensers 12, connected to the two other opposite points thereof. The primary 13 of the transformer is connected to an alternating current circuit 14, 15, and the other terminals 16, 17 of the filter circuit are connected to the plate circuit of the receiving set (not shown). Usually the circuit 14, 15 is of about 120 volts, in which case the. transformer ratio is about 1 to v1.3 to impress about 150 volts on the bridge.

These electrolytie cells deliver -about 80 milliamperes at about 150 volts for several thousands of hours. The rectiying films on the cathodes remain imperforate and adherent, and likewise `the protective film on the anodes. The cells start into operation almost instantly. The temperaturerise of each cell is only 5 C. from ordinary room temperature, after an output from the bridge of 30 milliamperes for 8 l hours. The eii- 30 mllliamperes output from the bridge.

Iclaim v. 1. In an electrolytic cell, acathode comprising aluminum, an anode, and an electrolyte containing a neutralized solution of a phosphate of ammonium and a chromate of potassium.

2. In an electrolytic cell, a cathode compris ing aluminum, an anode, and an electrolyte containing -a neutralized solution of monobasic phosphate of ammonium and a chromate 'of potassium.

3. In an electrolytic cell, a cathode comprising aluminum, an anode, .and an electrolyte containing a neutralized solution of monobasic phosphate of ammonium and potassium dichromate.

4. In an eleetrolytic cell, a cathode comprising aluminum, an anode, and an electrolyte containing a neutralized solution containing monobasie phosphate of ammonium 10 per cent to 20 per cent and potassium dichromate 0.1 per cent to 5 per cent.

5. In an electrolytic cell, a cathode comprising aluminum, an anode, and an electro- .lyte composed of a solution of monobasic phosphate of ammonium and a chromate of potassium rendered non-acidic with ammonlum carbonate. y

6. In an electrolytic cell, a cathode comprising aluminum, an anode, and an electrolyte 'composed of a solution of monobasic phos phate of ammonium and dichromate of potassium rendered non-acidic with ammonium carbonate.

7 In an electrolytic cell; an electrolyte containing a substantially neutralized solution of monobasic phosphate of ammonium and a chromate of potassium; a cathode containing aluminum mainlygand an anode containing iron mainly. f Y 8. In an electrolytic cell; an electrolyte composed of a solution of monobasic phosphate of ammonium, a chromate of potassium, and ammonium carbonate suiieient to neutralize the solution; a lcathode containing aluminum mainly; and an anodecontaining iron mainly. v 9. In an electrolytic cell; an electrolyte composed of a solution of monobasic phosphate Aaluminum mainly; and an anode containing ironmainly.

V10. In an electrolytic cell; an electrolyte composed of a solution of monobasic phosphate of ammonium, a chromate ofpotassium, glycerine, and ammonium carbonate sufcient to neutralize the solution; a cathode containing aluminum mainly; an anode containing iron mainly; and a steel container.

In testimony whereof I aiiix my signature ISRAELA. SHULI-MSON.

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