US1545941A

US1545941A - Art of electoplating

Info

Publication number: US1545941A
Application number: US755144A
Authority: US
Inventors: Edward A Coady; Frederic W Olmstead
Original assignee: Individual
Current assignee: Individual
Priority date: 1924-12-11
Filing date: 1924-12-11
Publication date: 1925-07-14
Anticipated expiration: 1942-07-14

Description

2 Sheets-Sheet 1 a QM? ATTORNEYS July 14, 1925.

E. A. COADY ET AL ART 0F ELEGTROPLATING Filed DBC. 11, 1924 .AJ/ulyL4 14,` 1925. l

E. A. COADY ET AL ART OF ELECTROPLATING 2 Sheets-Sheet 2 Filed Deo. 11, 1924 mm i lu 1 ATTORNEYS Patented duly 14, 1925.

aren vSTATES 1,545,941 PATENT oFFlcs.'

EDWARD A. COADY, F NEW YORK, AND FREDERIC W. OLMSTEAD, Oli" HEMPSTEAD, NEW YORK, ASSIGNORS. BY MESNE'ASSIGNMENTS, T0 FREDERICK CONLIN, OF

WESTFIELD, NEW JERSEY.

.ART 0F ELECTROPLATING.

Application led December 11, 1924. Serial No. 755,144.

T0 ZZ whom, it may concer/n.: Be it known that We, EDWARD A. CoADY c .and FREDERIC lV. OLMSTE'AD, citizens of the United States, and residents, respectively, of New York, county of New York, and State of New York, and Hempstead, county of Nassau, and State of New York, have invented certain new andi useful Improve'- ments in the Art of Electroplating; and we do hereby declare. the following to be a full, clear, and eXact'description of the invention, such as will enable others skilled inthe art to which it appertains to make and` use the same.

rIhis invention relates to an imp-roved brush for electrolytically applying metals, such as'nickel, to conducting surfaces. It has previously been proposed to apply nickel icoatings or plat-ings to conducting surfaces 2O by means of a brush withv an anode arranged so that electrolysis takes vplaces in the brush. The present invention. relates more particularly to improvements in. the construction of the brush employed in such operations; and this invention provides an improved brush which is easily handled,

which enables an expeditious and eflicientA application of such metallic coatings, 'which enables the application of vmetallic coatings 5o of good physical quality and of good lapypea-rance, and which has other important advantages which will appear from the folloi-ving descrip-tion and illustration., .Y

In a brush for this .purpose described in: an application of Frederick Conlin nliled January 12, 1925, Serial No. 1831 the anode is arranged within the bristle head of the brush so as to be wholly immersed in plating solution retained by theV bristles of the 40 brush. The anode is thus submerged in plating solution when. the brush is in -use so `that the maximum area of the anode is eX- posed and so that a moreuniform distribution of the flow of current throu h the electrolyte retained in the brush 1s promoted. Uniformity of distribution of the plating current assists in producing a metallic deposit of good physical properties and avoids burning of the metallic coatingdue to eX- cessive current densityvover localized areas.

In the improved brush of the present invention, the anode is similarly arranged to be wholly immersed in plating solution retained by the bristles of the brush, and a substantially rigid apron is arranged about the brush bristles so as to prevent any contact of the anode in the brush with the surface being plated while nevertheless allowing free movement of the brush bristles.

There no protection is provided to prevent contact between the anode and the surface` being plated, the flexing ofthe brush bristles may expose the anode which may thus b e contacted with the surface being plated. Such contact results in short-circuit causing excessive current flow and tending to mar thesurface by burning.` The physical contact of the anode also may .mar the surfalce being plated. By providing a substantially rigid apron about the brush bristles in the improved lbfrush of the p-resent invention, however, such contact 1s prevented without sacrificing free movement of the brush bristles or the ease of applying the brush yin .the plating operation.

This apron is advantageously flared outwardly away from the bristles of the brushj toward the applied end of the bristles to allow them to move freely within the ap-ron.

The apron need not completely enclose thev anode 'within the brush. The bristles, as arranged in a body in the brush, have a maximum angle of fieXure beyond which no ordinary pressure applied in using the brush will bend them. In the improved brush of the present invention, advantage is takenol" this maximum angle of iexure'bfy arrangthe brush may frequently be accompaniedby the liberation of gas.- The movement of the bristles of the brush over the anode immersed therein largely prevents polarization, but, where the gasv liberated is confined 1n thebrush, a somewhat-similar result may becaused mechanically by displacement of the electrolyte about the anode by. the-gas -liberated and confined inthe brush. 'This within the bristle head of the brush and so as causes overheating, reduces the capacity of y P'Ihe provision of gas relieving means is particularly advantageous where an otherwise 'gas tight apron'is employed, 4but certain ad- F' l tratflad' vantages are obtained by the provision of gas relieving means -in brushes without aprons.

he invention will be further described in connection with the accompanying drawings which show several brushes embodying the invention, but it will be understood that this yfurther description and illustration are for the purpose of exempliication and that the invention is not limited thereto. In the accompanying drawings: t Fig. 1-represents, in section, a flat brush embodying the invention, on line 1-1 of Fig. 2,

2 is a side View of the brushl illusin Fig. 1, Fig. 3 isa fragmentary view showing a. somewhat modified type of brush head,

Fig. 4' represents, partly in section, a modified type of brush embodying the invention, f .v Fig. 5 represents, partly in section, a circular-brush embodying the invention, and Fig. 6 is a section on line 6 6 of Fig. 5,. r The brush illustrated in Figs. 1 and 2 is made up of a separable brush head'7 and a handle 8. The brush bristles 9 are suitably4 vsecured vin the `brush head 7. The handle 8- vmay be .of ha'rd rubber or other suitable insulating and impervious material and the brush head 7 may also be of insulating material suzh as hard rubber. The bristles may be set in rubber in the head'as indicated at 10 in the drawing. lThe head 7 is provided with an apron 11 extending downwardly about the bristles 9 and flaring outwardly therefrom. The flare of the apron .advantageously corresponds to the natural curve of the brush bristles when in use, and the lower edge of the apron is rounded off to avoid undue wear of the bristles.- This .comprising lthe bristle settling and the apron are integral, as illustrated in Figs,v

` such gas does not tend to ldisplace the elec- 1 and'2.

' A holev12 isprovided through the brush head in -alignment with a corresponding 'hole 13 extending through the handle. An

anode 14 is supported within the bristles 9 by means -of a shank 15 extending up. wardly through the holes in the brush head' and handle. The edges of the anode are suitably beveled or rounded to avoid undue wear of the bristles. The upper endI of the l shank'lv is threaded and is arranged t0 en" gage an-adjusting nut 1,6 and a lock nut 17, the adjusting nut 16 cooperating with a co1- for v which the exposed end of the bristles are applied in the plating operation while4 at vthe same time allowing full and free\movement of the bristles. As in the brush illustrated` in Fig. 1, this result may be accomplished without extending the apron downwardly far enou h to completely enclose the anode but a lig ter and shorter apron may be emf ployed. As will be apparent by reference to Fig. 1, before the anode 14 cancontact with a .surface being plated it must protrude through the brush bristles. The brush bristles, however, loffer a certain resistance to lexure which gradually increases as they are bent and which, with a body of bristles as in the brush illustrated becomes so great at an angle of maximum de'xure that no ordinary. pressurewill further displace the bristles. With ordinary brush construction, this angle of maximum {iexure amounts to about 27 to 3Q? from the surface to which the brush is applied. Accordingly, in the improved brush of the present invention, the edge 20 of the apron 11 isA arranged so vthat no straight line from it to the adjacent the line A--B and the axis of the brush is advantageously e ual to or greater than about 63 but nee not be90.

The apron, 11, in the brush illustrated in Figs. 1 and 2, is provided with a series ot1| apertures 22A adjacent the handle -end or ixed end of thel brush bristles and just below the bristle setting 10. A vent 23 is also provided in the upper end of the handle communicating with the

holes

12 and 13 brush. In other words, the angle betweenYA through the brush head andthe handle.

Any gas liberated by the electrolysis taking place within the brush when lit is in use is thus provided with means for escape so'that faces or where it is applied to the underside or horizontal surfaces. In vsuch instances, with the shank a extending through the brush head and the handle, the electrolyte may tend to'leak along the shank through= the handle. To prevent this, a packing 24v is provided in the joint between the handle 8a and the brush head 7. A series of Vents are arranged in the apron on the brush head to allow for theescape of any gas formed during the electrolysis, and, to 1nh1b1t any leakage of electrolyte through these vents,

they are arranged in a part of the apron which is normally held in close contact lwith the brush bristles so that the brush bristles Iact to retain the solution While permitting the escape of gas through the apertures.

The brush illustrated in Fig. 4 is ofthe same'general construction as the brush illustrated in Fig. l except in the shape of the apron, in the absenceof gas vents, and in the provision of packing about the shank supporting the anode. This type of brush is particularly adapted for more or less continuous use in plating surfaces from the underside. Packin 24b is provided in the joint between the rush head 7l and the handle 8b to prevent leakage of the electrolyte along the -shank l5b supporting the anode. The apron 11b, instead of closely contacting i ith the' bristles 9" just below the bristle setting and then gradually flaring outwardly, is cup shaped to provide .a free space about the bristles from the bristle setting toward the free end of the bristles. In use, the brush is dipped in the plating solution and inverted, the cup shaped apron 1lb serving to hold excess platinar solution and to prevent dripping from the brush bristles. vIn the inverted position, any gas formed escapes toward the free end of the bristles. While a brush of this construction In the round brush illustrated in Figs. 5y

and 6, the anode 26 is in the form of a round rod arranged within the brush bristles 9 and'integral with the shank 15. Instead -of being integral with the brush head 7, the apron llc is separable therefrom. With vsome electrolytes, and where the brush is used but infrequently, the provision of a. separable apron may be desirable to facilitate cleaning of the brush. The anode and the supporting -shank'extend through the brush head and the brush handle 8c to the adjustable supporting means on the up-per end of the handle as in the brush illustrated in Fig. l.

In using the improved brush ofthe present porting shank, and the negative pole of the current source is connected to the conducting surface. to be plated. The brush is then saturated with a suitable electrolyte, as by 'dipping in the electrolyte solution, and is' applied to the surface to be plated. The plating solution is electrolyzed in the brush and the metal is deposited at the point of contact between the brush bristles and the conductingsurfaee. Thermovement of the brush bristlcs'ovcr the conducting surface to be plated, the cathode, promotes effectivel depolarization at the cathode, so that the plating operation proceeds smoothly and uniformly. The distance between the end of `thepanode and the end of the brush bristles is adjusted to promote uniform distribution of current flow through the electrolyte retained by the brush without unduly increasing the resistance through the brush.

In ,using the brush of the present invention for nickel plating, for example, an electrolyte containing 281 gms. of crystallized nickel sulfate (NiSO4-6I-I2O), 8 gms. of sodium fluoride, 30 gms. boric acid, and 2 gms. of glucose per litre may be used at ordinary temperature with a potential be- `tween the anode in the brush and the conducting surface to be plated of about 20 to 50 voltsor somewhat less. The brush is advantageously -connected in series with a resistance large enouglrto render the variation vin resistance in the brush when in use immaterial. For example, the brush may be connected to a. volt power line through a resistance of from about 25 to 40 ohmsA or more. For nickel plating, the anode is advantageously made of nickel so that. vit. will replace the nickel content of the electrolyte in the brush as the metal is plated therefrom. The shank supporting the anode may also be of nickel, or of some material 'l' substantially insoluble in the electrolyte such as lead, orcf some material lower in the electromotive series than nickel and which will not plate out of the solution such as iron.

Advantageously, the anode isv adjusted so that it does not come nearer to the surface to be plated than about the thickness of bristles around the anode. For example, in the brushes illustrated, the anode may be arranged about l from the end of the'bristles when the brush is free from contact with the surface to be plated; It is also advantageous to arrange the anode so that it has a surface exposed to the electrolyte in the brush equal to or greater than the area of contact between the brush and the surface to be plated when the brush is in use. (laissent densities isr-v bath practice may be employed-and a con-i sequent increase in the rate of deposition obtained without sacrifice of the quality or appearance of the metallic plating. Before application of the plating with the brush, the surface to be plated may be cleaned and vpolished in any of the well-known ways.

We cla-im:

' 1. An improved brush for electroplating conducting surfaces,'which comprises a brisvtle head and 'an anode arranged with and surrounded by the bristles, an electrical connection to the anode, and a substantially rigid apron arranged about the bristles.

2. An improved brush for electroplating conducting surfaces, which'comprises a brisv less than 90 but not less than about with the axis of the brush.

3; vAn improved brush for electroplating tle head andan anode, arranged within the bristles, an electrical connectionto the anode,

vand a substantially rigid apron arranged about the bristles, the lower ledge of the apron and the lower edge of the anode being arranged so that all sraight lines through adjacent points thereof make an angle of 63 conducting surfaces, which comprises a bristle head and an. anode arranged within and surrounded by the bristles, an electrical connection to thel anode, and :a substantially rigid apron arranged about the bristles, and flaring outwardly therefrom toward the apy plied end of the bristles.

' a substantially rigid apron arranged-about the bristles toward their free end, and aperthe bristles in close contact with-the bristles toward their fixed end and flaring away from tures through the apron-.where it is in close Contact with the bristles.

6. An improved brush for electro-plating conducting surfaces, which comprises a bristle head and a handle, an anode arranged Within .the bristles and supported on a shank extending through the handle, means on the handle for adjusting the position of the lanode along theaxis of the brush, an electrical connection to the anode, and a substantially rigidapron arranged about the bristles.

7. An improved brush for electroplating conducting surfaces, which comprises a bristle head and a handle, an anode arranged Within the bristles and supported on a shank extending through a hole in the bristle head and handle, means for relieving gas through the said hole, an electrical connection'to the anode, and a substantially rigid apron ar.

ranged about the bristles.

8. An improved brush for electroplating conducting surfaces, which comprises a bristle head and a handle, an anode arranged within the bristles and supported on a shank extending through a holel in the bristle head and handle, the hole being large enough to provide a free space. about the shank, an electrical connection to the anode, and a vent for relieving gas from the handle end of the said hole.

9. An improved brush for tle head and an anode arranged within the bristles, an electrical connection to the anode and means for relieving gas from the space in the bristles about the anode.

1 l0. An improved brush for electroplating conducting surfaces, which comprises abristle head and an anode within the bristles, an impervious apron 'arranged about the bristles, an electrical connection to the anode, and -means for relieving` gas from the space inthe brush Within the apron.

In testimony whereof we aiiix our signa-' tures. l i.

EDWARD A. ooAn'Y. vaanname W. onMsTEAD.

electroplating -conducting surfaces, which comprises a bris-