US964096A - Process for electroplating. - Google Patents

Description

THOMAS A. EDISON, OF LLEWELLYN PARK, ORANGE, NEW JERSEY.

'rnocnss or nLEcTnorLA'iING.

aeaoaa No Drawing.

Specification of-I etters Patent. Application filed March 19, 1906. Serial No. 306,781.-

Patented July 12, 1910.

To all whom it may concern:

' Be it known that 1,1IKO1WIAS A. EDISON, a

citizen of the United States, residing at Llewellyn Park, Orange, county of Essex,-

and State'of New Jersey, have invented a certain new and useful Process of Electroplating, of which the following is a description.

In carrying on experimental and commercial operations in connection with electro= plating, I find that the occlusion of hydrogen tends to make the deposit somewhat brittle and more or lessporous, and that hydrogen gas clings to the surfaces of the deposited metal in the form of very fine bubbles, thereby making the surfaces more or. less warty and rough. The presence of occluded hydrogen, aswell as of the hydrogen bubbles referred to, prevents the deposition at a high rate, and also results in Streaky and uneven deposits.

My object is to provide an imprloved process of electroplating, whereby I very largely eliminate the occlusion of hydrogen, as well as the formation of hydrogen bubbles on the deposited surfaces, and in consequence I am enabled to carry on a plating operation at a much higher rate than is now possible, and

at the same time with the production of a better quality of deposit, less brittle in character, practically free of pores, andwith a smooth and uniform surface.

' The invention resides in the fact that by maintaining in the plating bath a small quantity of material which will combine with the hydrogen, for example, free chlorin, the latter will combine with any hydrogen set free by the electrolytic action, or otherwise, thereby preventing the formation of metallic hydrates as well as the occlusion of thegas, and eliminating also the appearance of microscopic bubbles thereof, which cling to the deposited surfaces with the objections-pointed out. When free chlorin is thus presentinthe bath, it combines with any hydrogen generated therein to form hydrochloric acid, although it is possible that other favorablereactions may be brought about by the presenceof free chlorin. The chlorin may be added to the plating bath in anysuitable way, such, for example, as by passing the gas continuously, or at suitable intervals, through the bath; by adding to thebath, watersaturatedwith chlorin, or by adding from time-"t0 time fresh-quantities of'the electrolyte saturatedwith chlorin. For.instance, if copper is to be plated from a. solution of sulfate of copper, the chlorin can be added by chlorinating a suitable quantity of .-the solution, which can be added from time to time in small amounts to the solution as the chlordn becomes exhausted. In practice, the solution should have alslightly acid re.- action. I find that the eflect of the chlorin thus introduced into the bathlasts for several hours, when a fresh quantity must be added. In the case of a. chlorid bath (for carbon anode of very small surface can be connected to the metallic anode and made to continuously ehlorinate thesolution, as will be understood; Practically all of the chlorin,is utilized in combining with 'the hydrogen developed, there being very little loss of chlorin by its combination with either the anode or cathode. "Free bromin may also be employed, but with results that are far inferior to those secured when chlorin is used. The use of chlorin in cobalt plating baths is especially beneficial, and this is particularly true when cobalt-chlorid solutions are employed.

Having now described my invention, wha't I claim as newand desire to secure by Letters Patent is as follows 1. That improvement in the art of electroplating which consists in chlorinating a suitable quantity of copper sulfate solution, and adding from time to time in small amounts to thesolution in a copper. plating bath, 'as'the chlorin becomes exhausted by reaction with the hydrogen developed upon the cathode, substantially as set forth.

, 2. That improvement in the art of electro-plating which consists in chlorinating asuitable quantity of copper 'sulfate solution and addlng from time to time in small amounts to thmsolution in a copper'plating bath,;as the chlorin becomes exhausted by reaction with the hydrogen developed upbn slightly acid, substantially as set forth. the cathode, substantially as set forth. 10 3. That improvement in the art of elec- This specification signed and witnessed tro lating which consists in halogenizing a this 24th day of Febry 1906. 5 suitable quantity of copper sulfate solution, THOMAS A. EDISON. and addlng from time to time in small Witnesses: amounts to the solution in a cop er plating FRANK L. DYER,

bath, as the ,halogen becomes ex austed by ANNA R. KLEH the cathode, the solution being maintained reaction with the hydrogen developed upon