US1280213A - Method of and apparatus for electroplating. - Google Patents

Description

C. A. HACH.

METHOD OF AND APPARATUS FOR ELECTROPLATING.

APPLICATION HLED JAN. T2 191? Patented Oct. 1, 191&

2 SHEETS-SHEET Im/en 0r Clarence fllberTHacfi IMF. A W H C. A. HACH.

METHOD OF AND APPARATUS FOR ELECTROPLATING.

APPLICATION FILED JAN. 12. I9IT 2 SHEETSSHEET 2.

it a PATENT cuties.

CLARENCE ALBERT HACH, 0F OAK PARK, ILLINOIS, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YOR K, N. Y., A CORPORATION or NEW YORK.

Specification of Letters Patent.

Patented Oct. 1, 19118.

Application filed January 12, 1917. Serial No. 141,935.

To all whom it may concern:

Be' it known that I, CLARENCE ALBERT Then, a citizen of the United States, residingat Oak Park, in the county of Cook and State of Illinois, have invented certain new and usefulImprovements in Methods of and Apparatus for Electroplating, of which the following is a full, clear, concise, and exact description.

This invention relates to an improved method of and apparatus for electro-plating, and more particularly to a method of and apparatus for increasing the speed and efliciency with which the plating operation can be performed.

In electro-plating operations as practised commercially very small hydrogen bubbles are continuously evolved at the cathode or article to be plated, said bubbles having a tendency to adhere to the surface of the'article. These hydrogen bubbles prevent contact between the platin -solut1on and the surface of the article whlch is being plated, which interferes with the plating process at the point of contact and frequently results in the formation of pits in the plated coatmg.

This invention contemplates an improved method of and apparatus for rapidly removing said hydrogen bubbles, which makes it possible to use higher current densities and thereby to increase the speed of plating without pitting. In the preferred form of the invention herein illustrated and described these hydrogen bubbles are carried away by air liberated in the form of small bubbles directly under the article that is being plated, said air bubbles constituting a continuous stream, which bombard the surface of the article and carry with them as they rise to the surface of the plating solution the hydrogen bubbles which are being generated at the surface of the article and tend to adhere to said surface. The bubbling ofair through the plating solution also serves to agitate said solution, which action also makes it possible to increase the speed of plating. The process of air agitation for the purpose of producing circulation for plating solutions is old, and this result is obtained merely as an incident in the application ofthis new process, which seeks primarily to remove the hydrogen bubbles by air agitation and which also accomplishes secondarily the circulation of the plating solution. While the process of removing the hydrogen bubbles by a bombardment of air bubbles is beneficial and applicable to practically all electroplating processes, it is especially applicable to the plating process in which the anodes are shaped to conform to the contour of the article that is be- 2-2 of Fig. 1 looking in the direction of the arrows, and

F 1g. 3 1s a vertlcal sect10n of an anode on the plane 3-3 of Fig. 1 looking in the direc-' tion of the arrows.

The apparatus is all mounted in the plating tank or receptacle 10 which carries a suitable plating solution. In the bottom of said tank, as illustrated in Fig. 2, is a heating steam coil llhaving an inlet at 12 and an outlet at 13 which is utilized to heat the plating solutionand keep it at a temperature at which the plating operation can be most satisfactorily performed. Directly above the heating coil 11 is a second coil 14 which is equipped with a' series of perforations and which is connected at 15 to an air supply lead which furnishes compressed air to the coil. The compressed air supplied to the coil escapes through the perforations and through the plating solution out into the atmosphere of the room. This escaping air functions to produce a circulation of the plating solution in the tank, and since the coil is placed at substantially the lowest portion of the tank, the escaping air will produce practically the same amount of agitation throughout the entire'volume of the tank. Mounted near the upper portion of the tank are two brackets or shelves 16 and 17 which serve as supports for the anodes such as 20. These anodes may be of any desired shape or form, but are preferably made so as to conform substantially to the shape of the article to be plated. In the preferred embodiment of the invention herein illustrated the articles to be plated such as 19 have a somewhat irregular shape which accentuates the special shape of the anode 20,

as clearly illustrated in Fig. 3. The various anodes 20 are mounted in perforations in the shelves 16 and 17 and are each equipped with a plurality of perforations such as 21 which facilitate the proper circulatlon of the plating solution from the exterlor of the anode' into and through the interior of the anode and back into the solution outside of the anode.

Mounted directly beneath each of the- .equal to the area of the filtros. The filtros may be connected either directly to this opening or may be seperated therefrom very slightly, as indicated in Fig. 3, so as to permit circulation of the plating solution through this lower opening in the anode.

The article 19 to be plated is secured to a lug 27 depending from a rod such as 28 by any suitable means which will permit speedy and eflicient attachment and removal of the article from said lug. The lugs 27 are connected to the rods 28 having a relatively high electrical conductivity, preferably copper, and these rods are m turn connected to a frame 29. Each end of the sides of this frame is given a'slightupward inclination, as shown in Fig. 2, and these ends .of the frame constitute handles whereby the frame and the attached rods and cathodes 0r articles to be plated can be readily removed from the plating tank. When the articles to be plated or cathodes are lowered into the plating solution and the various anodes 20 for plating, the rods 28 associated with the cathodes or articles to be plated will rest on the copper frame 30 which is mounted on the top of the tank 10 by means of the insulating locks 31, 32, 33, and 34. Attached to the copper frame 30 is the terminal lug .35 which is connected to one terminal of the electrical circuit which supplies the plating current. Extending completely across the middle portion of the tank is the copper rod 36 to which the various anodes are connected by means of the copper bars 37 38, 39,-and 40, the copper rod 36 being connected to the other termination of the circuit which supplies the plating current.

to be plated have been lowered into the various anodes 20 by means of the frame 29,

and the current is connected to the frame 30 and the rod 36, the current will flow from the anode through the plating solution in the anodes to the articles 19'to be plated and back to the other terminal of the circuit by way of the rod 36. This will start the metal depositing action from the plating solution onto the articles to be plated, and this action will be accompanied by the generation of very small bubbles of hydrogen on the surfaces of the articles that are being plated. As long as thesebubbles are very small they have a tendency to cling to the surface of the article, and such bubbles prevent contact be tween the plating solution and the surface of the article and little or no' metal will be deposited on the article at the place of contact between the article and the bubble until the bubble is removed. To remove these hydrogen bubbles, the compressed air in the tros located between the lower opemng in each anode. The air is filtered through the filtros in such a way that the resulting bubbles rising therefrom are very minute in size and likewise very great in number. These air bubbles rapidly rise through the plating solution contained in the anode and strike the surface of the article which is being plated. In this manner the'compressed aid from the pipe line 22 is released in a continuous flow of bubbles under each article which is being plated, said air bubbles bombarding the surface of the article that is being plated and carrying with them the hydrogen bubbles that are being generated on the surface of the article, due to the platingoperation. This continuous bombardment of air bubbles keeps the surface of the articles which are being plated substantially clear of hydrogen bubbles, permits a greater speed in the plating operation, and prevents the forming) of pits in the plated surface. The air bub les rising through the solutioncontained in the anode also function to circulate this solution and draw fresh solution from the tank through the openings in the lower part of the anode, so that the solution within the anode will always be rich in metal content which is necessary for speedy, eificient, and satisfactory plating. The use of the compressed air means for the removing of hydrogen bubbles in the process of plating consequently results in a speedier and more efficient plating process and also in a much more satisfactory product. I T

Obviously the invention is not limited to the specific embodiment hereinshown and described, but is capable of many variations and applicatlons without departing from its sp1r1t and scope, as set forth inthe apa pended claims. When a plurality of articles such as 19*.

What is claimed is: 1. An improved process of plating which .consists in automatically removing the bubbles of hydrogen as they are generated on the surface of. the cathode during the plating operation by a continuous stream of bombarding gas bubbles, said bubbles being maintained minute in size by filtration through an inert porous material whereby said bubbles are uniformly distributed to impinge against the entire surface of said cathode which is to be plated.

2. In a device for plating articles, the combination with-a solution containing receptacle, a cathode, an anode, a source of current supply connected to said cathode and said anode, pneumatic means comprising a constant stream of gas which generates bubbles to remove the hydrogen bubbles generated on the article connected to said cathode during the plating operation, and an inert porous material through which cathode.

said gas is filtered prior to the formation of said bubbles.

' 3. In a device of the character described, the combination with a solution containing receptacle, of a cathode, an anode shaped to conform substantially to the shape of the cathode, a source of current connected to said cathode and said anode, pneumatic means comprisinga constant stream of gas operated to remove hydrogen bubbles generated on the cathode during the plating operation, and a filter comprising an inert porous material located beneath the cathode through which said gas is forced before reaching said In witness whereof, I hereunto subscribe my name this 29th day of Dec, A. D. 1916.

CLARENCE ALBERT HACH.

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