US2467852A - Electrolytic sheet metal anode - Google Patents

Description

W. L. PINNER ELEGTROLYTC SHEET METAL ANODE Filed March 23, 1944 April 19, 1949.

Patented Apr. 19, 1949 UNITED STATES PATENT OFFICE.

ELECTROLYTIC SHEE'l METAL ANODE Walter L. Pinner, Detroit, Mich., assignor to Hwdai c-H s ey C r r n, Detroit, M ch-i a: corporation of Michigan Application March 23, 1944, Serial No. 527,731

3 Claims. 1

This invention relates to an electrolytic sheet metal anode for use in the electrodeposition of the metal forming the anode. The invention pertains particularly to long composite anodes formed of electrolytic nickel sheets.

In the electrodeposition of nickel, it has been customary to employ rolled or cast nickel sheets, in spite of the lower cost per pound of electrolytic nickel. Although electrolytic sheet nickel is obtainable in the open market in lengths up to 36 inches, such short lengths of electrolytic sheet nickel have not been generally used as anode material even where long anodes are not required.

Electrolytic sheet nickel may satisfactorily be substituted for rolled or cast nickel as anode material for nickel-plating. However, when two electrolytic nickel sheets are joined together end to end, to form anodes longer than 36 inches, such as are required in large industrial nickel-plating operations, the resulting joint is preferentially attacked when the composite anode is exposed to corrosion in a plating tank, so that the lower sheet falls off long before the composite anode has been reduced to scrap by corrosion. Whether the joint is formed mechanically, as by employing a dovetail joinbetween the anode sheets, or by riveting, or by welding, the joint isin all cases subjected to preferential electrolytic attack.

I have now found that either a mechanically formed joint or a welded joint may be shielded against preferential electrolytic attack in any of several ways. The joint may; for instance, be temporarily protected by providing a relatively non-porous and non-conductive layer or coating over the joint, such, for instance, as an elastic rubber band. After the anode has been in use $0. some time, corrosion will have progressed sufficiently far to permit the removal of the rubher band or other shielding means without bringing about. any excessive subsequent attack on the joint.v

Acecrding to another phase ofmy invention, nst ad f; complete y protect n the o nt a ainst pref r nt al ec ro ic. attack. he joint. ay be hi d a a nst ex s e el ctrol tic attack so as to re ard. the cor o on o undercut of t e joint sufficiently that it will not catch up with the corrosio of the lo r hall oi th wel ed o nos t anode un i af er h shie din m ans it.- el ha b n on me In th s case the sh d n m n m y suitab c m r e anode. scrap tha sb n attached len w t t e c mnosite anod in. s h manner a o e i and part all over t at ide f the jQintin. he om osit anode. facing ork, or catho e.-

For instance, if the composite anode comprises electrolytic nickel; sheets welded together end to end, one or more scrap nickel anodes may be attached lengthwise, as by welding at their ends, so as to overlie the joint in the composite sheet nickel anode. The scrap nickel anode, being thus subjected to preferential electrolytic attack, retards the corrosion of the main welded joint between the electrolytic nickel sheets so much that it will not catch upv with the corrosion of the lower half of the welded anode until after the scrap anode has been consumed. In this way, the lower half of the welded anode will not drop off before the anode has-corroded so far as to render it inoperative and fit only for scrap.

It is therefore an important Object of the present invention to make available electrolytic metal sheets, and particularly electrolytic nickel sheets, in lengths greater than those formerly available on the market, so that the same can be eificiently used in the electrolytic deposition of the metal of which the electrolytic sheets are fo e It is a further important object of this in-.- vention to make available electrolytic metal sheets, and particularly electrolytic nickel sheets, in the form of relatively long composite panels, joined together through the metal of the sheets themselves, with the joints shielded from preferential electrolytic attack during use.

It is a further important object of this invention to provide a relatively long composite welded electrolytic nickel sheet anode formed from electrolytic nickel sheets not available in the lengths desired and provided with means for shielding the welded joints against preferential electrolytic attack when the anode is in use and the welded joints are immersed within an aqueous plating bath.

Other and further important objects of this invention will be apparent from the disclosures in the specification andthe accompanying drawings, which show ccmposite metal anodes embodying the present invention.

On the drawings; I

Figure 1 is a vertical transverse sectional view through a nickel plating; will; Sho ing composite nickel sheet anodes embodying my invention disposed in position for plating.

Figure 3 is avf rent elevational view of a composite nickel sheet anode according to this in-' vention.

Figure 3 is a side elevational view of the anode of F ur 2- Ficure 4 is an e lar ed, a m n a y-view of the composite metal anode of Figures 2 and 3, showing the top of the anode with the suspending hook broken away.

Figure is a broken elevational view, with parts in section, of a modified form of my composite sheet metal anode.

Figure 6 is a, sectional view taken substantially along the line VIVI of Figure 5.

Figure 7 is a broken, elevational view, with parts in section, of a further modified form of my composite sheet metal anode.

As shown on the drawings:

In Figures 1 to 4, inclusive, the reference numeral I0 indicates generally a composite sheet metal anode embodying the principles of this invention. In the preferred form of my invention, the composite metal anode is formed of a plurality of sheets of electrolytic nickel, but it will be understood that electrolytic sheets of other metals, such as copper, may be used in forming the composite anodes hereinafter described.

The composite anode III is preferably formed of a pair of panels I I and I2, each of which comprises a pair of electrolytic nickel sheets, such as the sheets I Ia and i lb and the sheets I2a and I2b (Fig. 3). Each of said nickel sheets I Ia, IIb, I2c and I2b, may be such as are ordinarily available from the refinery in lengths up to thirtysix inches. The individual sheets are then joined in pairs to form the panels II and I2 and. the panels are joined together at their upper edges for connection to a suspending means, thereby making a com osite anode of the desired length where such length is longer than thirty-six inches.

More particularly, each of the pairs of sheets Na and III), and I2a and I2b, are joined together in end-to-end relationship by means of welds H0 and I20, and the two panels II and I2 thus formed are superimposed on each other and connected together at one end by a weld I3. Thus, for instance, if the sheets I Ia, I lb, I and I2b are 32 inches long and 4% inches wide, the anodes formed from these sheets will be 64 inches long and 4 inches wide and will contain two thicknesses of electrolytic sheet nickel. Anodes of lengths other than 64 inches but longer than 36 inches may be similarly formed.

The weld I3 preferably joins the upper edges of the two sheets II and I2, the lower edges of which are joined by separate welds II c and I2c to the lower sheets I II) and I2b, respectively. As best shown in Figure 4, the weld I 3 is also utilized to attach to the composite anode a nut I4, into which a terminally threaded hook I5 may be screwed. The hook I5 enables the composite sheet anode to be suspended from a bus bar, or other conductor of electrical current, for immersion of the anode in the electrolyte of the plating bath. When the anode is immersed, the welds I I0 and IE0 are, of course, submerged below the surface of the electrolyte. This is best illustrated in Figure 1, where the reference numeral I6 indicates a plating tank, provided with anodic bus bars 2I and a cathodic bus bar 22. Articles to be plated, such as the articles 23, are suspended below the surface of the plating bath 24 by means of a rack depending from the cathodic bus bar 22.

If a composite anode were formed only of electrolytic nickel sheets welded together and then used without any provision for protecting the submerged welded joint, such as the welds He and I2c, the lower nickel sheets I II) and I2b would fall off before the anode as a whole had been F I2 that lies toward the cathode.

reduced to scrap dimensions. This is because the metal around the welds, due to the heat treatment caused by the welding operation, corrodes more rapidly than the rest of the metal of the anode. Consequently, if unprotected, the welds would be corroded most rapidly and fail, letting the lower portions, such as the sheets IIb and I2b, fall off into the plating bath.

To avoid too rapid corrosion of the submerged welds H0 and I2c, I attach to the composite anode ID, in front of the anode face that is to be turned toward the cathode, such as the articles 23, a piece of nickel that at least partially covers the welds I20 and He that are to be protected. A corroded anode reduced to scrap dimensions may advantageously be used for this purpose. In Figures 1 to 3, inclusive, such a scrap anode is indicated by the reference numeral I1, and is shown attached to the composite anode ID at its upper and lower ends by welds I80. and I8b, respectively. The upper weld I8a is preferably at such a point as to be above the level of the bath 24 when the anode is in use.

When the welded composite anode I0 is thus provided with the scrap anode II, the welds I2c and I I0 are protected against too rapid corrosion until the scrap anode I! has been consumed so far as to completely expose the weld I2c. By that time, however, the corrosion or undercutting of the weld I2c can no longer catch up with the corrosion of the lower sheet I2b of the panel I2, and the same is also true of the other panel II since the weld II c of that panel is protected both by the scrap anode IT and also by the panel Consequently, the lower sheets I21) and Nb are largely, or completely, consumed before the welds I20 and He are corroded sufficiently far to give away.

The application to the face of the composite sheet nickel anode of anode scrap, so as to cover the submerged weld at least partially, thus retards the preferential attack of the electrolyte of the bath 24 on the metal of the weld. Were it not for this retarding or protecting action against the action of the electrolyte, the metal of the welds, or the heat treated metal contiguous to the welds, would tend to be attacked preferentially or more rapidly than the metal of the anode sheets proper. This is true even where the metal of the welds is the same metal, namely nickel, as the metal of the electrolytic sheets.

The scrap anode I1 illustrates the condition of an anode according to this invention when corroded to scrap dimensions. Originally the anode IT was a full-size composite anode like the anode II! described hereinabove. Corrosion consumed the first layer of nickel sheets, leaving the second layer in the condition illustrated at the time the anode had to be scrapped. It will be noted that, the weld I1c joining the two electrolytic metal sheets I'Ia and III) has not been corroded or undercut enough to permit the lower sheet "D to drop off. On further corrosion of the scrap anode II, the lower sheet IIb would be consumed entirely, and would not fall off, since the metal is by then suificiently porous to corrode as rapidly as the welded joint IIc.

In place of using two thicknesses of panels. such as panels II and I2, each composed of sepa rate sheets joined end-to-end, it is, of course, possible to use a single thickness panel or to unite more than two panels together. The upper and lower edges of the superimposed panels may be welded together, or only the upper edges need be welded. The protective scrap anode may eattendovermore' or less of the lengthor the'composite anode, and may cover the weld o1"wel'ds tobe protected more or less completely. More than' one' scrap anode may be affixed to the composite anode, and if a plurality of scrap anodes are thus attached, the scrap" anode may be arranged in the manner of shingles, one end only being welded to the anode proper and that welded end being covered by an overlying piece of scrap anode.

The anodes of this invention may thus be characterized as comprising sheets oi electrolytic nickel joined end-to -end through the metalof the sheets, as by welding, and having on that face turned toward the cathode at least one piece of nickel smaller than the composite anode in surface area and covering the weld, or welds, at least partially. This smaller piece of nickel pro- }tects the weld and adjoining parts of the virgin provided, the first thickness, havin been proi tected by a scra anode, will in turn protect the secondthickness, or second panel, when after complete consumption of the scrapanode, corrosion' of the'first thickness; or panel; exposes the secondpanel to corrosion. In this manner, practically all of the electrolytic nickel used for anodes is consumed, and less scrap nickel is left to be disposed of by sale or otherwise.

In the modified form of my invention, illustrated in Figures and 6, a pair of electrolytic nickel sheets, such as the sheets 39 and 3!, are joined together by a mechanical joint, such as the dovetail joint 32. For this purpose, the end of the sheet 39 may be formed with a reentrant type of groove or recess 32a, while the end of the sheet 3! is formed with a similarly contoured tongue 32b adapted to mate with the groove 32a. There is thus produced a panel 33 which may be used like the panels H and I2 for building up a composite anode.

If a panel such as the panel 33 were used Without any provision for protecting the joint 32 against attack by the electrolyte during the plating operation, the joint 32 would be likely to failbefore the anode as a whole had been reduced to scrap dimensions. Upon failure of the joint, the lower sheet 3! would drop or: into the plating tank before giving maximum service, thereby giving rise to a large scrap figure and to poor plating. The reason for failure at the joint 32 is that the attack of the electrolyte is concentrated at the edges formed by said joint, so that the corrosion is more rapid at that point. This is a dififerent reason than that given in connection with the welded type of anode previously described, where the welded joint corrodes much faster than the un-heat-treated metal in the body of the anode.

According to my present invention, I provide a relatively non-porous and non-conductive layer or coating over the joint 32 to protect temporarily, or as long as necessary, against excessive electrolytic attack and resultin corrosion. For this purpose, an elastic rubber band 34 is stretched and slipped over the joint 32 to overlie all of the edges forming such joint. A composition of rubber is selected that is known to be resistant toward the action of the particular electrolyte with which the anode panel 33 is to be used.

* when the panel is made-up into a composite sheet metal'anode, like the anode l-ll'above described,the joint 32 is, of course, submerged in the electrolytic bath 24. During the operation of the plating bath the rubber band 34 protects the joint 32" against-excessive corrosion due to electrolytic attack. After the anode has been in use for a longer orshorten time, corrosion of. the sheets 'a-nd3I willhaveprogressed sufiiciently far to permit the removal'of the rubber band 34 without bringing about any excessive subsequent attack on-the joint 32. In this way excessive preferential attack of the joint 32 is retarded in order that themaximum' consumption of the metal-of the sheets 30 and 3| can be realized.

Figure 7 illustrates a still'further modification of anodeconstructi'on. As there illustrated, a pair ofelectrolytic' nickeF sheets 35 and 36 are joined together by a weld 3"! in end-to-end relationship to form an elongated panel'38. A strip of lead'39 is then wrapped-around the welded joint 31: to protect the same against preferential electrolytic attack during meet the panel 33 in a composite anode such as'already'described. The lead strip 39' thus may serve the same function as the rubber" band 34. Theme of a lead strip in a nickel plating bath would produce no harmful result where the bath isof the low chloride type, containing for instance less than grams per liter of nickel chloride (NiCl'z' 6H2O), or where the baths'arenot of the'oxidized' type that produce nascent chlorine.

A lead strip suchas" the lead" strip 39 may also be used with the mechanical type of joint such as the joint 32""illustrated in Figure 5. Other types of mechanical joints than the dovetail joint 32 may also be employed. This type of joint has been found, however, to be very satisfactory, since the mating tongue and groove can be cheaply formed in a punch press and the mating portions so formed then forced together in a press to provide a good electrical joint through the metal of the sheets themselves. It is not necessary that a dovetail joint be employed since any joint providing good structural and electrical contact, and capable of being blocked off or shielded from preferential electrolytic attack, will serve equally well.

In place of using a non-porous and non-conductive material such as rubber for overlying the mechanically formed or welded joints, plastic compositions of the bakelite or other synthetic resin type, a stop-off lacquer, or the like, a vitreous ceramic material, or even glass, may be used, but where this type of protection is used, I prefer to employ bands of rubber or rubber composition since they may be so easily slipped on and ofi.

The provision of a composite sheet metal anode, such as the anode l0, makes possible the use of electrolytic metal sheets in anodes of any desired length and weight. The composite anodes may thus be made to weigh the same as a cast or rolled metal anode to the same length. This means that it is unnecessary to replace the composite sheet metal anodes of my invention any more often than in the case of rolled or cast metal anodes of the same weight.

This application is a continuation-in-part of my applications Serial Numbers 307,403, filed December 4, 1939 and 413,249, filed October 2, 1941 which have now become abandoned.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles 7 of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims,

What I claim is:

1. A composite metal anode for use in the electrodeposition of the metal of which said anode is formed, which comprises a plurality of sheets of electrolytic metal, pairs of said sheets being joined together lengthwise through the metal of the respective sheets to form elongated panels and the panels being connected along their upper edges, a suspending member secured to said connected upper edges, and means temporarily protecting the joined together portions of said panels from electrolytic attack durin the early stages of the use of said anode in electrodeposition work.

2. A composite metal anode for use in the electrodeposition of metal of which said anode is formed, which comprises a plurality of sheets of electrolytic metal, pairs of said sheets being joined together lengthwise through the metal of the respective sheets to form elongated panels and the panels being connected along their upper edges, a suspending member secured to said connected upped edges, and means temporarily protecting the joined together portions of said panels from electrolytic attack during the early stages of the use of said anode in electrodeposition work, said protecting means including a non-porous, nonconductive material over-lying the joined together portions of the panels to shield the joint against attack by an electrolyte to which it is subjected during electrodeposition work.

3. A nickel anode comprising two superimposed layers of electrolytic nickel sheets, the sheets of each layer being welded together end-to-end and the two layers being welded together at their top edges, suspending means attached to said welded top edges and electrolytic nickel anode scrap welded to an exposed face of one of said layers to overlie the weld and to cover at least part of the width of said weld between the ends of the sheets of said layer.

WALTER L. PINNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 114,191 Parmelee Apr. 25, 1871 745,479 Cann Dec. 1, 1903 753,819 Atkins Mar. 1, 1904 882,110 Hill Mar. 17, 1908 1,331,571 LeSueur Feb. 24, 1920 2,043,823 Young June 9, 1936 2,324,342 Wellman July 13, 1943 FOREIGN PATENTS Number Name Date 6,102 Great Britain Mar. 23, 1901 426,110 Great Britain Mar. 2'7, 1935 617,451 France Feb. 19, 1927 OTHER REFERENCES Electroplating with Chromium, Copper, and Nickel, 1930, page 128, Freeman and Hoppe, Prentice-Hall, Inc, New York, New York.

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