US902755A - Electrolyte for electroplating. - Google Patents

Description

'ing oi the "airy irr ro Marian, ora1'cnMoNn,vIaGINIA ELECTEOLYTE FOB ELECTROPLATING.

Specification 01 Letters Patent.

latented Nov. a, 1908.

hppimation filed Marsh 22, 1001. Serial No. 863,879.

ful Improvements in. Electrolytes for Electroplating; and I. do hereby declare the following to be a full, clear. and exact descri r ti' n of the invention, su h as will. enable others skilled in the art lo which it upper tuins to make and use ih'e same.

This invention rolalvs to improvements in electrolytes f r i-leoiropluiing, and the object in \ltW is the hir ng and facilitatcan of eluclroplating pun-oases. in the (:arr 'iw i esses herelmon aqueous hail like or lhe cathode ha lurbingg clcmciu lic a tendency repb-iing proc filii lfljyl of an Hon of h drogen at a: hy'ilri ma n the; rim, :siled metal poi? ons, or own coon; this olistaclc and to a w y'hl' met at the cathode arious imp-"ore! baihs are used. All of lhcm have a inoee or less complicated composition, which mus; be lrcpl up by regeneration, and als the current density per square foot oi cailm-ilc surface must be carefully lffiglllillwll l ix-ipir-miy the temperature of the bail: must he l-iiegn 'within certain limits.

Iii-carryingout my invention, .5 employ an electrolyic comprising a. solution of a chlorid of a. nn-tal in alcohol, ll alcohol being either ccninuerr-ial ecliyia ilnl. or lnethylalcohol, or denatured alcohol.

()ne way of preparing an electrolyte is lhe dissolving of a chlorid of a metal to be plated in the alcohol, and this may be iwil' sidered the normal or prrlcrrul way of tho pre )aratiou of the ci'.* ."i1'ui l(. it if. (he \unerlying principle of lhrp24 .l inwntiori to restrict the evolution uli hydrogen by restricting the percentag oi \Yulli in the electrolyte to that small amount of water which exists in cornn'iercial alcohol, any about five per cent. But even a few per cent. more will make little or no practical difference. and therefore a second way of preparing lhc electrolyte is possible and consists of adding one or several per cent; of pure, consent: LL l hydrochloric acid to commercial alcohol and starting electrolysis, usinq the plating metal as an anode. Chlorid oi the plating metal is thus formed in the bath, and the process is a: the most dis.

carried out by the use of the plating metal itself as the anode without a chlorid of metal being in the first instance dissolved in the alcohol. In this Way, alcohol, with the addition of a small amount of pure hydrochloric acid, forms directly, While cold and without further additions, an excellent electrolyte for a number of metals, although not for all metals. Gold, copper, nickel, cobalt, tin, and iron can be deposited in this way to advantage, and in a dense, bright and metallic form.

It is obvious from the foregoing that whether the chlorid of metal isdissolved directly in alcohol in the first instance, or is produced at the anode in the electrolyte, the resultant electrolyte comprising a chlorid of a metal and alcohol is comprehended by the present invention.

From two and one'half to three volts is required for overcoming the resistance of the bath and carrying out the present improved electroplating process by the use of the electrolyte as above described.

When compared with the present welllanown aqueous baths, the readiness with which the present improved electrolyte may be produced and used will be more fully appreciated. The aqueous baths which are at present commonly used have a complicated com p .tion which must be kept up by regeneration. and the current densities er square foot of surface to be plated must we strictly maintained. In the present invention it is not necessary to adhere strictly to certain current densities. No heating of the bath is required.

The presentimproved method or process cannoi' oc used for silver and lead. [tmight be used for platinum and zinc, but in the case of these two last mentioned metals, I should. prefer the improvedaqueous baths. As far as platinum is concerned the anode does not dissolve and the addition of platinum chlorid must be kept up. Also the platinum deposited is darker than can be obtained otherwise. As to zinc, the same results, or perhaps even better, can be obtained with cheap aqueous solutions. I

As the present improved electrolyte is of similar nature for all metals used, the present method oflers a variety of Ways of de positing different metals as alloys with each other. above each other, or side by'side in the seine both. This can be done by the addition of new chlorfds, or it can be done moved entirely from the bat entirely 1) suitable manipulation of the anodes an by stopping or starting circulation in the electrolyte. Certain anodes may be moved, or lifted iartiall ,,or re' ing a rod of a different metal as anode close to a certain point of the cathode, 1t 18 POSSI- ble to deposit a different metal on this part of the cathode, while at other places other metals are deposited. In this way copper and zinc may be deposited simultaneously and so also copper and brass; and zinc,

nickel, cop er and tin may form a variety of colors on t e same cathode.

I have been .unable to deposit aluminum by itself, according to the present improved method or rocess. However, when other metals are eposited, aluminum in the electrolyte will make its appearance at the cathode, and in this case it either changes the looks or character of thedeposit, or it appears in films or patches of aluminum metal. These patches have a tendency to be blackish, but show the color of aluminum when polished.

Another advantage of the present improved electrolyte for electroplatin same is found in connection with p ating upon aluminum, as it has been heretofore practically impossible to electroplate aluminum in the same way as other metals are electrotyped, and various special methods have been proposed to plate aluminum with other metals. With my improved method, aluminum may be plated upon like any other metal, and in the same way. It is only necessary, when starting, to reverse the poles for a few minutes, thus making the aluminum 1 cathode for a few minutes the anode, and then the poles are reversed again and the plating is carried on in the usual manner. The theory of this form of plating on the aluminum is as follows :Alum1num is always covered with a thin film of an oxid. When the surface is scraped, or the metal is cut with a knife, the film forms itself immediately, if the aluminum is in air or in water. -This film prevents the electro deposited metal from adhering-to the aluminum. In making the aluminum for a few minutes the anode, I dissolve this film, and it does not form again in alcohol, and therefore when the aluminum becomes the cathode again, the electro deposited metal strikes upon real, bare aluminum and adheres to it.

What I claim is, a

1. An electro-plating bath, comprising a solution of a chlorid of a plating metal in alcohol.

2. An electro-plating bath comprising a solution of chlorid of a plurality of plating metals in alcohol.

3. In an electrolyte, a solution of chlorid *of copper in alcohol. the

4. In an electrolyte, a solution of chlorid of copper and a chlorid of another metal in alcoho 5. In an electrolyte, a solution of chlorid of copper and chloride of other metals in alcohol.

In testimony whereof I afiix my signature in presence of two witnesses.

OTTO MEYER.

Witnesses:

E. V. FARINHOLT, O. C. RUSSELL.