US1566984A - Electroplating method and electroplated articles - Google Patents

Description

Patented Dec. 2 2 1925.

Io Drawing.

- UNITED STAT'ES PATENT OFFICE.

ROBERT-JAY SHOEMAKEB, OF CHICAGO, ILLINOIS.

ELECTBOPLATING METHOD AND EL ECIBOPLATED ARTICLES.

To all whom it may conccm Be itknown that I, ROBERT J. SHOE MAKER, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Electroplating Methods and Electroplated Articles, of which the following is a specification.

My invention relates to methods of electroplating, and more especially to the electroplating of iron or steel articles such, for example, as boiler tubes, sheets, pipes, castings and forgings. The invention is of particular utility in electroplatingiron or steel articles with lead inasmuch as it provides,

l electrolysis iron or steel articles (and hereafter throughout the specification and claims I- shall use the term iron as coveringboth species), but so far as I .am aware, it has not been found possible heretofore to carryout this operation satisfactorily. If the surface to be covered is slightly greasy or has any scale adhering thereto, even of a microscopic character, the uniformity, density and ho-.

. mogeneity of the lead plating will be affected. It is diflicult if not impossible even by pickling the article in acid to clean the" surface to be plated sufliciently to make the coating even, non-porous and uniformly adherent. There is also a tendency of the lead to deposit in streaks, that is, in irregular strips with intervening spaces less thickly covered. The reason forthis is. not fully understood but the phenomenon'is recognized-b those who have made experiments along t is line.

The lead will also deposit more readily and densely on surfaces that are smooth than on rough surfaces so that variations in the character of the iron surface due to inequali- -.ties in rolling and other like causes, affect the character of the lead deposited by electrolysis on such surface.

There is also a tendency, during the eleclyj to blister.

Application filed October 1, 1928: semi No. 865,951.

trolytic operation, for the lead to tree out from the article and eventually produce a short circuit. It .does not seem possible to prevent treeing even with mechanical agitation.

Moreover, the lead coating does not adhere to the iron as firmly as is desired. An electro-plated lead boiler tube, for example, if boiled in acids commonly used for testing these articles as to their corrosibility, is like- Portions of the plating are loosened from the iron so as to be easily rubbed off.

* Finally, it has not been found possible so 4 far as I am aware, to cover an iron wit a lead plating produced electrolytically which will be dense enough to prevent corrosion of the iron through the plating. This is also true of iron bodies -electro-plated with tin, nickel and copper.

The primary objects of my invention are,

therefore: first, to provide a practical method of. electro-plating iron articles with lead and, second, an improvement in the methods of electro-plating iron bodies, regardless of the plating metal used, to prevent the rusting through of the iron.

Other less important objects will be re ferred to inconnection with the following.

description of the preferred manner of practicing the invention.

The method will-be described first in connection with lead plating. N

(a) The body or article to be plated is first pickled and cleaned in the usual Way with sulphuric acid or some other suitable cleansing acid. It may afterward be washed with water but that is not necessary. 4

(b) 7 his then immersed in a dilute solution of a copper salt capable of reacting by substitution with the iron, which solution preferably contains an inert agent serving to retard the corrosive action of the solution on the iron. The solution is prefer ably composed of the following ingredients: 100

Copper sulphate, 2 parts (by weight);

water, parts; glue, 1 part; commercial sulphuric acid, 1 part. Copper chloride may be used'in place of cop er sulphate. The

function of the glue is to s ow down the corrovided care is taken that the articles should 0 Otherwise the iron would. be too not remain in the bath too long. The reaction is in the sense of the following equations, depending upon whether copper sulphate or copper chloride is used:

This treatment covers the article with a thin coating of copper.

(c) The article is then immersed in a Cu-l-HgGhzCuCh-l-Hgl A film of mercury is formed over the copper coating, the mercury amalgamatin'g with the copper. The effect seems to be to make the cop er adhere more firmly to the iron and-to 211 the pores of the copper coating, which is relatively porous,.so that a stratum is provided over the iron base which is very dense, smooth and of uniform character.

Instead of using the solution of mercury salt for producing the mercury film over the copper coating, metallic mercury might be rubbed on the copper coating. The operation, however, is diflicult and expensive.

((1) Assuming that the article has first been copper coated and then treated 'with the mercury salt solution, it is then washed to remove the adherent chloride.

(6) The next step is the electroplating operationwhich may be carried on with the use of any suitable electrolyte, such as lead silico-fluoride or, more desirable on account of economy, lead acetateJ Using lead acetate, the solution is preferably as follows:

Lead acetate, 10 parts (by Weight) commercial lime acetate, 10 parts; acetic acid, 1 part; water, 100 parts.

The electrolyte is kept in slow agitation by means of a pump orcompressed air during the process. The function of the lime acetate, in place of which ammonium acetate or sodium-acetate may be used, is primarily to reduce internal resistance. Incidentally the. organic impurity,'to-wit, compounds of pyroligneous acid, serve to prevent treeing. The current flow should be approximately one ampere per square foot of surface plated and the. potential from four to six volts.

' Metallic lead is used as a positive pole.

It will be understood. that in the electroplating of articles with metals other than lead, thepreparation of the article for treatneeaesa ment in the electrolytic cell would be the same as describedin steps (a) and The operation of copper coating described as step (6) maybe used to advantage without subsequent step (c) a copper electroplating operation precedent to immersion of the article in the electrolytic cell. In this case the solution should be strengthened to containabout 10% copper salt.

Steps (1)) and (6), whereby the body is covered with a coating consisting. of an amalgam of copper and mercury, may be advantageously used in preparing billets for cold drawing into pipes, tubes, and the like.

The coatingprovides an excellent metallic lubricant. which, lfnecessary, may be removed by pickling in case it is necessary to anneal. the billet between draws.

The operations described as steps (a) and (d) might be used advantageously as a pretreatment in the lead tin or nickel plating of copper, brass or bronze articles.

I claim:

1. Improvement in the method-of electroplating iron articles which consists in covermg the surface of the article to be plated with a permanently adherent film of mercury and a metal with which mercury will amalgamate and thereafter electro-plating said surface.

2. Improvement in the method of electro-, plating iron articles which consists in coating the surface of the article to be plated with copper and covering the cop ered surface with a film of mercury prior to the electro-plating operation.

Method of electro-plating iron articles which consists in immersing the article in a solution of a copper salt capable of reacting by substitution with the iron to coat the article with copper, covering the coppered surface with a film of mercury, and then electro-plating the mercury covered surface.

4 Method of electro-plating iron articles which consists in immersing the, article in a solution of a copper salt capable of reacting by substitution with the iron to coat the same with copper, immersing the article in a solution of a mercury salt capable of reacting with the copper to produce an amalgamation of metallic mercury with the copper coating, and then electro-plating the' solution of copper salt capable of reacting by substitution with the iron and containing an agent for retardin the corrosive action of the solution on the non to coat the article with copper, immersing the article in a solution of a mercury salt capable of reacting cle which consists in immersing the article in an aciduated solution of copper sulphate or .itsequivalent to produce a reaction in the sense of the equation Fe-|-CuSO,=FeSO,+Ou;

immersing the article in a solution of mercuric chloride or 1ts equivalent to produce a reaction 1n the sense of the equatlon I and then electro-plating the article.

8. Method of electro-plating an iron arti-.

cle which consists in immersmg the article in an acidulated solution of copper sulphate or its equivalent, and containing glue, to

' produce a reaction in the senseof the equaimmersing-the-article in a solution of mercur1c chloride or its equivalent to produce a retarded reaction in the sense of the equa-.

tion 7 p v r Cu+HgCl =CuCl +I-I ,g, and then electro-plating the article.

9. Improvement in the method of electroplating iron articles with lead which consists in coating the surface of the article to e be plated with copper and covering the coppered surface with a film of mercury prior to the electro-plating operation.

10. Method of electro-plating iron arti-- cles with lead which consists in immersing the article in a solution of a copper salt capable of reacting by tsubstitution with'the iron to coat the article with copper, covering the coppered surface with a film of mercury,

- and then electro-plating the mercury covered surface. i

11. Method of electro-plating iron articles with-lead which consists in immersing the article in a solution of a copper salt capa-- ble of reacting by substitution with the iron to coat the same with copper, immersing the article in a solution of a mercury salt capable of reacting with the copper to produce an amalgamation of metallic mercury with the copper coating, and then electro-plating the surface so treated.

12. Method of electroplatingv iron arti-' cles with lead which consists in immersing the article in a solution of a copper salt iron and containing an agent for retarding the corrosive action of the solution on the iron to coat the article with copper, covering the coppered surface with a film of mercury, and then electro-plating the mer-i curycovered surface. p

13. Method of electro-plating iron articles with lead which consists in immersing" the article in a solution of copperjsalt capable of reacting by substitution with the iron and containing an agent for retarding the corrosive action of the solution on the iron to coat the article with copper, immersing the article in a solution of a mercury salt capable of reacting by substitution with the copper to produce an amalgam of metallic mercury with the copper coating, and then electro-plating the surface so treated.

14. Method of electro-plating an iron article with lead which consists in immersing the article in an acidulated solution of ,copper sulphate or its equivalent immersing the article in a solution of mercuric chloride or its equivalent and then electro-platingthe article.- 1 v -15. 'Method of electro-plating an iron article with lead, which consists in immersing the article in an acidulated solution of copper sulphate or its e uivalent, and containing glue, immersingt e article in a solution of mercuricchloride or its equivalent and then electro-plating' the article.

16. Method of producing a metal coating oniron articles which comprises treating the article with a solution of copper salt capable of reacting by substitution with the iron and containing a retarding agent to slow the corrosive action of the copper salt solution on the iron.

17. Method of producing a metallic coating on iron articles which comprises treating the article with a solution of copper sulphate or its equivalent containing glue to retard the corrosive action of the solution on the iron. a

18. Method of producin a metallic coating on iron articles whic comprises..first covering the article with a coating of copper and then covering the copper surface with mercury.

. 1.9. Method ing on iron articles which comprises treating the article with a solution of a copper s'alt capable of reacting by substitution with the iron and then treating the coppered surface with a solution of a mercury salt capable of a substitution reaction with the copper coating. 20. Method of producing a metallic coat mg on iron articles which comprises treating the article with a solution of a copper salt of producing a metallic coatcapable of reacting by substitution with the a capable of reacting by substitution with the iron and containing an agent to retard the corrosive action of the copper salt solution I on the iron, *and then treating the coppered surface With a solution of a mercury salt capable of 'a substitution reaction with the copper coating.

21. Improvement in the method of electroplating which consists in covering the surface to beelectroplated with acopper coating and covering the copper coating with a film of mercury.

22. Method of electroplating which compriees dissolving in the electrolyte a soluing a stratum of mercury amalgamated with copper. I

24:. An electroplated iron article having between the iron surface and the electroplatr ing first a coat of copper in contact with the iron and over the copper a' film. of mercury.

25/13 lead plated iron article having between the surface of the iron and the lead underthe electroplating 'a coating of copper and over the copper a film of mercury.

ROBERT JAY sHoEMAKEn