US1682846A

US1682846A - Electrolytic rectifier

Info

Publication number: US1682846A
Authority: US
Publication date: 1928-09-04
Anticipated expiration: 1945-09-04

Description

Sept. 4, 1928. 1,682,846

H. c. KREMERS ELECTROLYTIC RECTIFIER Filed July 16, 1926 INVENTOR f/arg/ C Kre/77ers ATTOR H EYS Patented Sept. 4, 1928.

UNITED STATES PATENT FFEQ.

HARRY C. KREMERS, OF UBBLNA, LLINCIS.

ELECTROLYTIC RECTIFIER.

Application filed July 1S,

y :consist of al group of elements, located in the third periodic group and resembling each other rather closely chemically andphysical- Y ly. 'The' rareearth group consists of the followingelementsarranged in Athree groupings the ceriunrgroup, includingl lanthanum, ceri- "um,1 praseodymium, neodymium,'illinium and sa rium the terbium group, .including'europium, 1gadoliniun'i, terbium; and the yttrium group, including dys'prosium, holmium, yttrium, erbium, thulium, ytterbium, lutecium and scandium. v

In the occurrence of these elements in nature, the cerium group with small amounts of the terbium group and in most cases with lesser amounts of the yttrium group is found in such minerals asA monazite sand. ceritc, ctc. Likewise the yttriu'm group with vsmall amounts of the terbium group and still'lesscr amounts ofthe cerium group is found in minerals such as gadolinite, fergusonite, etc.

Thust-here can be obtained Without much eiforttwo rather distinct groups of rare earth metals: thecerium group proper with some ltei'bium group material, and the yttrium group proper, also with some terbium group material. With the exception of cerium, the separation and preparation of the individual elements of any one of the three groups mentioned is a very slou7 and difiicult task. Since theelements of the cerium group are so similar in nature, the entire group may be reduced to metal. This metal appears on the marketl in an alloy known as misch metal (mixedmetal). The chemical properties ot misch metal are quite similar to that of any vone of the individual elements. This com mercial misch metal as it appears on the market Yhas usually the following approximate composition: lanthanum-20%, cerium-35%, neodylnium-QOf/Vf, praseodymi- 11m- 57%, @madam-10%, terbium group- 7% and. yttrium group-3%. The yttrium group has also been reduced to metal in an experimental Way only and called yttrium mixed metal.

In experimenting with various alloys ot the rare earth metals, and particularly misch metal, it has been discovered that if two brightly polished plates of such metal are vdue to, the formation of a 1926. Serial No. 122,802.

placed in an elcctrolytic solution and the two plates connected to the terminals of an electric battery or other source of unidirectional voltage, an instantaneous How of current occurs. After a few minutes the current is found to drop ofi' to a negligible value, such l. the drop .inthe curas a few milli-amperes. rent being accompanied by, and apparently film of oxide on rare earth metal the posit-ive batanode is allowed before it is subthe metal anode, that is, the plate which is connected to tery terminal. If the metal to tarnish or oxidize in air merged in the electrolyte, the current flow is very small or negligible when the battery is first connected thereto.

It has been further observed that the rare earth metal plate which is used as a cathode, that is, the plate connected to the negative battery terminal, acts as a good cond ctor of electric current from the electrolyte. Thus, it is seen that the rare earth metals behave as conductors when they function as cathodcs and behave as non-conductors when they function as anodes` The anode used to produce this effect may be composed of any one of the rare earth metals alone, such as cerium, lanthanum, praseodymium or neodymium, or may comprise an alloy of one of these metals or an alloy of misch metal. The electrolyte used may be a solution of sodium or potassium hydroxide, sodium phosphate. borax, boric acid or certain neutral or alkaline salt sollitions or mixtures composed or" alkalies and salts.

It a cell using a non-corrosive or non-filming electrode or plate such as lead or carbon, a misch metal plate and an electrolyte, (as mentioned above) preferably sodi um4 hydroxide solution, is connected by means of the lead and misch metal plates to an alternating current ot a suitable voltage, the current flow in one direction is almost entirely shut oil and a direct pulsating current is obtained. In such an arrangement the flow of current is accompanied by an elcctrolytic action in the cell, with evolution of hydrogen gas at the misch metal and oxygen gas at the lead. The action ofthe misch metal (or other rare earth metals) is such that electrons are permitted to flow from the misch metal plate to release hydrogen ions but are prevented from passing from oxygen ions into the solution.

It is an object of the present invention to provide an electrolytic rectifier employing as an electrode one of the ra re earth metals or an alloy or mixture of several or all of such metals, together with a suitable electrolyte.

It is a further object of this invention to provide an electrolytic rectifier of this type which may be used to convert an alternating current into a unidirectional current which is suitable for charging storage batteries, operating radio apparatus and for other puroses. v Y

It is further contemplated to provide the electrolytic cell employing electrodes of rare earth metal or metals which may be f,used as a lightning arrester, as an electrolytic condenser Aorfor any otherA purposev or function to whichelectrolytie cells are applicable.

, In describing the invention in detail, reference will be made to the accompanying drawings, in which Figure 1 represents, in a diagrammatic and simplified manner, an electrolytic rectifier embodyingthe present invention;

Figure 2'1rlepresents a modified form of electrolytic rectifier'desig'ned to rectify the full alternating current wave; andA Figure 3 shows a further modification of the invention employing a multiplicity of electrolytie cells connected in series and provided with means for eliminating undesirable fluctuations in the output current.

The electrolytic. cell of the present inven tion will now be described as used in.conneetion with the rectification of alternating currents, it being understood that this represents only one manner in which this cell may be employed, and that the cell may be used in various other ways. In Fig. l o f the drawings, a source of alternating current is connected as shown to the primary winding of the transformer 1, the secondary circuit of which includes in series therewith an electrolytic cell Z comprising a suitable electrolyte as described above, a rare earth metal plate 3 and a plate 4 of carbon lead or other suitable non-corrosive material. The sccondary circuit including the cell in .series may be connected to the negative terminal 5 and the positive terminal 6 of the storage battery whereby such battery may be charged, or this secondary circuit may be connected to any other device, circuit or apparatus requiring a unidirectional current for its operation. The cell 2 being in series in the secondary circuit allows current to flow in one direction only, thus rectfying one half of the alternating current waves.

By the use of two plates of rare earth metal1 shown at 7 and 7 in Fig. 2, with a single plate 8 of carbon, lead or other suitable material, the full alternating current wave may be rectified. In this arrangement, the

plates

7 and 7 are connected to the opposite terminals of the secondary winding of the transformer 10, the direct current output circuit being connected between the carbon plate 8 and a center tap 9 of the transformer secondary. In this arrangement current may How from the tap 9 through the external direct current circuit, returning to one or the other of the

plates

7 and 7 through the carbon plate 8 and the electrolyte, the return of the current in the reverse direct-ion being prevented by the action of the rare earth metal electrodes as described above.

In the modification shown in Fig. 3, the secondary winding of a transformer 11 has its terminals connected to two batteries, 12 and 12 of electrolytic cells of the'type describedh the individual cells of each battery being connectcd in series. The return of the direct current output circuit is connected to a'center tap of the transformer secondary, and the operation of this arrangement issimilar to that of the arrangement shown? in Fig'. 2. The output circuit of this rectifier may be provided with asuitable filter circuit,such `as the

condenscrs

13 and 13 and the series connected choke coil 14, this filter circuit acting in the well known manner to suppress or choke outVA variations or ripples in the rectified current. The form and -arrangeriient of the rectifier shown in Fig.l 3 is particularly applicable to radio work in which a comparatively high voltage is required in connection with the well known A andB circuits of audion tubes. The use of several cells in series permits the rectifica-tion of a zcomparatively high voltage, as the voltage of the secondary circuit is tributed over several cells in series.

It has been found that various alkaline solutions may be used as the electrolyte in the electrolytic cells of the -present invention. One solution -which gives very satisfactory results is a 25% solution of sodium hydroxide and water, although various other sodium hydroxide solutions give satisfactory results.

The rectifier con=tructed in accordance with the present invention has many advantages over the now known types of electrolytic rectificrs. The efficiency of the present. rectifier is found to be very much better than the efficiency of the usual aluminum element rectifier, being substantially equal to the efficicncy of a rectifier of the electron valve, or tantalum electrode type. In addition, the rectifier of the present invention canbe manufactured at a much lower cost than can thc rectifiers of the electron valve or tantalum type, the misch metal being readily obtainable at a comparatively low price.

The rectifiers constructed in accordance with the present invention are particularly applicable t0 use in connection with charging storage batteries, in electrodeposition of metal, and in other electro-chemical reactions, and also in radio work, but these recti fiers are also well adapted for use wherever direct current is required and an alternating current. supply is available. The electrolytic cells may also be used in electrolytic lightning dis- .Y

1,682,846 3 arresters of the Well known type, two rare non-filming conducting material, a filming earth metal plates or electrodes being submerged in a suitable electrolyte and acting to resist the flow of current until a predetermined high voltage is impressed between the plates.

Although the present invention has been described in connection with certain .specific apparatus and devices, it should be understood that the cell of the present invention, and the action between the rare earth metals and the electrolyte therein is capable of general application, and the invention is therefore not limited to the specific embodiment-s shown. The cells may be provided with any suitable number and arrangement of both rare earth metal and non-filming electrodes, the meta-l used for the filming electrode may be varied as described above, and the electrolyte used may be any suitable alkaline salt solution. Moreover, the connection between the electrodes and the cells may be varied to suit the desired opera-tion of the device, and many other changes, Amodifications and combinations may be made without departing from the scope of the invention as defined by the appended claims. f

I claim:

l. In an electrol tic cell, a lming electrode of rare earth metal.

2. In an electrolytic cell containing an electrolyte, a filming electrode composed at least in part of rare earth metal.

3. In an electrolytic cell containing an electrolyte of alkaline salt solution, a filming electrode of rare earth metal including cerium.

4. In an electrolytic cell containing an electrolyte and having at least one electrode of electrode of rare earth metal.

5. In an electrolytie cell containing an electrolyte and having at least one electrode of non-filming conducting material, al filming electrode containing cerium.

6. In an electrolytic cell containing an electrode of non-corrosive metal and an electrolyte of alkaline salt solution including sodium hydroxide, a filming electrode composed at least in part of cerium.

7. In an electrolytic cell having an electrode of non-corrosive metal and an electrolyte including sodium hydroxide, a filming electrode comprising a mixture of rare earth metals from the cerium, terbium and yttrium groups.

8. In a rectifier comprising a source of alternating current and an electrolytic cell connected in series therewith, a filming electrode composed at least in part of rare earth metal.

9. In an electrolyt-ic cell having an electrode of lead submerged in an electrolytic solution including sodium hydroxide, a. filming electrode composed of rare earth metals including cerium, lantlianum and neodymium.

l0. A filming electrode composed of rare earth metal.

1l. A filming electrode composed at leastin part of cerium.

l2. A filming electrode composed of rare earth metals from the cerium, terbium and yttrium groups.

13. A filming electrode composed of rare earth metals includingr cerium, lanthanum and neodymium.

In testimony whereof I aflix my signature.

HARRY C. KREMERS.