US921943A - Process for electrically coating with tin or allied metals. - Google Patents

Description

UNITED sTATEs PATENT curios.

JAY C. BENEKER, OF WAUKEGAN, ILLINOIS, ASSIGNOR TO THE MEAKER 00., OF CHICAGO,

ILLINOIS, A CORPORATION OF ILLINOIS.

PROCESS FOR ELECTRICALLY COATING WITH TIN OR ALLIED METALS.

To all whom it may concern:

Be it known that I, JAY CARL BENEKER, a citizen of the United States, and a resident of the city of Waukegan, in the county of Lake and 'State of Illinois, have invented certain new and useful Improvements in Processes for Electrically loating with Tin or Allied Metals, of which the following is a specification.

The use of a solution containing a salt of tin or allied metal such as antimony, platinum, gold or mercury or mixture of any. two (2) or more of these when an allo is to be deposited that can form a so-cal ed sulfosalt of an alkalineor alkaline earth metal.

The object of the invention is. to render the process more expeditious, considerably. cheaper, and to afford a homogeneous coating of uniform thickness and density. v In carrying out my invention I use a solution containing an ous or an ic salt of tin or an allied metal capable of forming a so called sulfo-salt of an alkaline or alkaline earth metal, of a mixture of any two or more of such s'alts when an alloy is to be deposited. An alkaline or an alkaline earth hydrate, preferably sodium hydroxid and an alkaline thio sulfate such as sodium thio sulfate better known as hyposulfite, are used.

Vihile I do not limit this application to definite proportions, these may of course be varied and I recommend the following formula as giving satisfactory results for tin coating: 25 parts sodium hydrate, parts sodium thio sulfate, 10 parts crystallized stannous chlorid, 200 part water. Preferably a solution is made of each, mixing the solution of stannous chlorid and sodium hydrate. When the solution is complete add the sodium thio sulfate. The solution. thus formed ma be used either hot or cold as an'electrolytic bath when plating, but I prefer to use it hot. T he reaction that takes (place is probably as follows:.lhe tin chlori combined with the sodium hydrate forming sodium stannite,

.znaonq sno,=Nao1+N ,s o,+H,o. i The thio sulfate then transforms this stannite Specification of Letters Patent. Application filed June 27, 1907. Serial No. 381,008.

to a sulfo-salt changing all or most of the Patented May 18, 1909.

stannous to'the stannic form. Probably the chief ingredient in the final solution is sodium thio-stannate Na -SnS This com pound in a high degree can be electrolyzed without the tin separating in a spongy or tree form.

For tin coatings I employ thio sulfate for the purpose 'of transforming alkaline or alkaline earthstannites to alkaline or alkaline earth thio stannates, thus changing the valency from the ous to the ic form in which form only are the thio salts of tin known. These sulfo compounds are also formed even when the valency is not changed as" in the case where mercuric or stannic salts are made the starting point.

With this solution'using any convenient anode. but preferably one containing the metal to be plated out, excellent deposits of tin-or an allied metal can be plated out without t 1e formation of a spongy or treelike deposit, even when using high current densities. The solution containing a goodly excess of caustic soda as in the above stated proportions-permits the tin or any suitable metallic anode used, to go into solution quite readily even when using high current densities thus assuring a solution of fairly constant metallic content.

Of course my process is applicable to the plating of metals from their ores in which case a carbon or other insoluble anode is preferably used. A

I claim as my invention 1. An electrolytic solution for tin comprising a solution formed of solutions of ser ium hydrate and sodium thio sulfate to which a solution of stannous chlorid in proper .proportions is added.

2. An electrolytic plating solution of tin comprising approximately parts sodium hydrate, 15 sodium thio sulfate and 10 parts stannous chlorid and 200 parts of water.

In testimony whereof I have hereunto "subscribed my name in thepresence oftwo subscribing witnesses.

.Witnesses:

K. E. HANNAH, J. W. ANGELL.

JAY o. BENEKE-R.