US3376209A - Anode formed of lead base and duriron - Google Patents

Description

April 2, 1968 R. c. SABINS v I ANODE FORMED OF LEAD BASE AND DURIRON Filed Nov. 6, 1964 ok mm vm QM INVENTOR.

HOLLAND C. SAB/NS A T TORNE Y 3,3762% Patented Apr. 2, 1968 lice 3,376,209 ANODE FORMED 01F LEAD BASE AND DURIRON Rolland C. Sabins, 522 Catalina Blvd, San Diego, Calif. 92106 Continuation-impart of application Ser. No. 407,302, Oct. 29, 1964. This application Nov. 6, 1964, Ser. No. 412,873

Claims. (Cl. 204-196) The present invention relates to an electrolytic system and to an anode for said system. More particularly, the present invention is directed to an electrolytic system for preventing galvanic dissolution of cathodic material and is directed also to an anode which is relatively inexpensive yet has the characteristics of expensive substances such as platinum.

The present invention is a continuation-in-part of my copending application Ser. No. 407,302, filed Oct. 29, 1964, now abandoned.

In practicing the present invention, an extraneous source of direct current is impressed upon the system to increase the potential of the cathode to above its dissolution potential.

It is known that when an attempt is made to use a single body of some substances, such as lead, as an anode in a galvanic system employing, for example, sea water as the electrolyte, such substances become passive to the flow of current and therefore can function as an anode only during the period prior to the substances becoming passive.

I have discovered that by physically associating several of the elements, such as iron and silicon in intimate contact with and exposed to the outer surface of such substance, such as lead, such mass becomes a composite anode and remains sutficiently active so that the entire outer surface thereof, which is exposed to the electrolyte, functions anodically and that such substance ceases to dissolve after being coated by a compound including the substances, such as lead, and the substances such as iron and silicon which are decomposed by an electric current while in the electrolyte.

Further features and the advantages of the present invention will be apparent from the following description, reference being bad to the accompanying drawing wherein a preferred embodiment of the invention is illustrated.

In the drawing:

FIG. 1 is a diagrammetic view illustrating a galvanic system wherein my invention is employed;

FIG. 2 is a fragmentary view of a metallic structure of cathode material, as for example, the hull of a steel ship, together with the fragmentary view of the improved anode;

FIG. 3 is a sectional view of the anode taken on line 3-3 of FIG. 2; and

FIG. 4 is a fragmentary sectional view taken along line 44 of FIG. 2, but on a larger scale.

Referring more in detail to the drawing and particularly to FIGS. 2 and 3. I have shown a cathode at 20, which may be any metallic object or objects which is or are to be adapted to be polarized and in which it is desirable to maintain a substantially uniform polarization of the entire surface which could be affected by galvanic action. Thus, for example, the cathode may be the hull of a ship and is herin shown as such. The composite anode is shown at 22 and will be described more in detail hereinafter.

The electrolyte may be any suitable compound, such as water or earth. For illustrative purposes, the cathode is shown as embedded in an electrolyte, for example sea water, the level of which is indicated by the dot and dash lines 22.

1 face of the lead, passivity of the anode The cathode 20, anode 22 and electrolyte are connected in galvanic relationship through a circuit including a source of direct current. This source of direct current is illustrated by two wires 24 and 26, 24 being connected to the negative terminal and 26 to the positive terminal of the source of direct current. The circuit includes a wire 24, ammeter 28, wire 30, variable resistance 32, wire 34, cathode 20, the electrolyte, anode 22 and wire 26.

To protect metal from corrosion, the relative potential at the surface of the metal must be increased to transpose the normal positive ionic surface state to an impressed negative ionic state. For example, a steel structure cathode has a potential of 630 millivolts with reference to a silver-silver chloride reference anode. It is known that to protect the shipss hull, made of steel, from corrosion in sea water, a potential should exist of approximately 890 millivolts, depending upon varying factors, and accordingly the potential of the steel cathode must be raise approximately 260 millivolts to prevent galvanic corrosion of dissolution of the metal, which corrosion or dissolution results in pitting. This increasing in potental is accomplished by subjecting the cathode to the electron flow in the external circuit. The variable resistance 32 is used to regulate the potential to that necessary for raising of the potential of the cathode.

The reference electrode is shown at 36 which is connected with the cathode 20 by wire 38, millivoltmeter 40 and wire 42.

Some compounds, and a number of the elements, enter a passive state when they are functioning as an impressed current anode in certain electrolytes subject to required current density and time. That is, the surface coating material becomes more passive to the passage of electrons when the electrolyte is decomposed by the current flowing therethrough, as for example, in the ionic exchange phenomena. In certain of these elements or compounds, the passivity thereof increases to such an extent that it substantially completely isolates the surface conductive of the electrode from the electrolyte enviornrnent. Such is true with respect to the metals aluminum, lead, and other metallic compounds.

I have discovered that by physically associating, with an anode 22 formed of a lead base a small piece or small pieces of the elements iron and silicon at the sur- 22 is checked, i.e., after a certain stage of decomposition of the electrolyte, no further dissolution of the lead takes place. Upon reaction with the electrolyte, a compound is formed in a thin layer only about the entire surface of the composite anode which is being subjected to the electrolyte. It is belived that this compound is a peroxide of lead. Due to the presence of the iron and silicon at the surface of the lead, the forming of the compound stops at a stage in which the entire surface of the whole anode functions as an anode but without further dissolution of the lead.

Thus, in effect, the entire surface of the relatively inexpensive lead functions to perform substantially the same service as an equal area of the highly expensive platinum in that it is relatively inert, yet functions as an anode.

My observasion has been that the entire surface of the anode functions as an anode, since gases are evolved throughout this entire area, most of which gases as yet have not been identified but is chlorine as would be the case if the entire surface of the anode was platinum anode surface.

The iron and the silicon should be in intimate contact with the lead, that is, both of these elements should be fastened in some manner to the lead. The iron and silicon could be in the form of a unit and this composition can be pressed or clamped on to the lead. In one form of the invention, balls, shots, or fine pieces of the composition 43 of iron and silicon are entered into the mold at the time that the lead is cast in the desired shape. The composition being less dense than lead, it will float to the top of the lead casting and therefore be exposed to the surface of the lead. These balls, shots, or pieces are in the form of a random pattern and the composition comprises 80% to 85% of iron and 15% to respectively, of silicon. The composite anode 22 need include less than one percent of the composition of iron and silicon for satisfactory results. Excellent results were achieved using lead and a composition sold under the trademark Durion.

Preferably the anode comprises a series of lead tubing or cables, having cast therein and at the surface thereof, the balls, shots, or pieces of the composition of iron and silicon. These lead cables are shown at 44. These cables 44, extend longitudinally and are suitably fastened to the cathode, herein shown as the outer side of the hull of the ship. They have a diameter of three-fourths inch, in actual practice. Vertically extending steel plates 48 are suitably welded to the outer surface of the hull. They are tapped and threaded as at 50 for receiving bolts 52. The composite anode 22 also includes a plurality of vertically extending anode parallel bars 54, each having a plurality of transverse or horizontally extending semicircular grooves 56 for receiving the cables 44. These bars 54 are formed of the same material as the cables 44 and also carry at the surface thereof, the composition iron and silicon. The anode including the cables 44 and the bars 54 are insulated from direct contact with the hull of the ship and likewise, the plates 48 by dielectric material such as vertically extending strips 58 and 60. The nylon strip 58 is provided with three transverse or horizontally extending semi-circular grooves 46. The grooves 46 in the nylon strip 58 and groves 56 in the bars 54 complement the cables 44. The nylon strip 60 is provided with semi-circular grooves 62 which extend transversely, i.e., horizontally and these grooves complement the periphery of the arcing shape of the 'bars 54. The bolts 52 pass through holes 64 and 66, respectively, in the nylon strips 58 and 60 and when fastened securely, the composite anode including cables 44 and bars 54 are secured to the plate 48.

Steel bars 68 and 70 are disposed, respectively, above and below the anode and are welded to the outer surface of the hull and thereby assist in guarding the anode should the ship encounter wharfs or the like.

The coating is not shown in FIGS. 2 and 3, but is shown at 72 and the random dispersement of the composition of iron and silicon is shown at 43. While such dispersement is shown in elevation in FIGS. 2 and 3, such is for illustrative purpose only since the coating 72 covers the entire surface of the composite anode 22 as shown in FIG. 4.

The word cable as herein used may take various forms such as tubing, strands of wire, and may have shapes other than cylindrical.

Thus, it is apparent from the foregoing that I have materially reduced the cost of inert anodes since the same results are achieved for like amount of surfaces heretofor deemed necessary in noble metals such as platinum or lead alloyed with a noble metal,

While the method herein ferred method, it is to be understood that other methods may be adopted falling within the scope of the claims that follow.

I claim:

1. A control system for preventing corrosion ofv a metallic structure which is subjected to an electrolyte, comprising in combination:

(A) a source of direct current having the negative side thereof connected with the structure; and

(B) A composite of said source trolyte, said anode comprising a alloy of iron and silicon in intimate contact and exposed to the electrolyte at the outer surface of said lead base to maintain the anodic activeness of the entire surface of the lead base.

2. A system as defined in claim 1, in which said alloy comprises to iron and 15% to 10% of silicon.

3. A system as defined in claim 1, in which said alloy constitutes a fraction of one anode.

4. A system as defined in claim 1, in which said alloy constitutes a fraction of one percent of the composite anode, and in which said alloy comprises 80% to 85% iron and 15% to 10% of silicon.

5. A system as defined in claim 1, characterized in that of current and subjected to the elec pead base and an the lead base is an elongated bar insulatingly fastened.

to the structure.

6. A system as defined in claim 1, characterized in that the structure is a hull of the ship and said anode is fastened to the hull substantially horizontally and below the water line.

7. A composite anode comprising:

(A) lead base;

(B) and an iron-silicon alloy exposed at the outer surface of the lead base.

8. An anode as defined in claim 7, in which the alloy constitutes a fraction of one percent of the composite anode.

9. An anode as defined in claim 8, in which the alloy comprises 80% to 85% iron and 15% to 10% silicon.

10. An anode as defined in claim 7, in which the alloy comprises 80% to 85% iron and 15% to 10% silicon.

References Cited UNITED STATES PATENTS 546,328 9/1895 Hoepfner 204-290 628,676 7/1899 Pollak 136-76 1,302,959 5/1919 Page 204-290 1,788,485 1/ 1931 Gunderson 204-196 1,984,899 12/1934 Smith 204-196 3,043,765 7/1962 Bryan et al. 204-196 3,108,939 10/1963 Sabins 204-196 3,284,333 11/1966 Parsi et al. 204 -196 3,294,667 12/1966 Giufirida 204-196 FOREIGN PATENTS 77,881 10/ 1894 Germany.

HOWARD S. WILLIAMS, Primary Examiner. T. TUNG, Assistant Examiner.

described constitutes a preanode connected to the positive side with percent of the composite UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,376,209 April 2 1968 Rolland C. Sabins It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 51 "cathode" should read cath l ne 59, 3." should read 3, line 60, cancel 22 1111i 65, cancel "be". Column 4, line 12, "pead" should read ea Signed and sealed this 5th day of August 1969.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer WILLIAM E. SCHUYLER, JR.

Claims (1)

1. 7. A COMPOSITE ANODE COMPRISING: (A) LEAD BASE; (B) AND AN IRON-SILICON ALLOY EXPOSED AT THE OUTER SURFACE OF THE LEAD BASE.

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