US1061066A - Plated metallic body. - Google Patents

Description

I G. A. GOODSON.

PLATED METALLIC BODY.

APPLICATION FILED MAR. 11, 1907.

. Lea/d k Z M llloy.

Patented May 6, 1913.

GEOBGE.A.- GOODSPN, OF MINNEAPOLIS, MINNESOTA.

PLATED ME'rALLic 3on1.

Specification of Letters Patent.

' Patented May 6, 1913.

Application filed March 11, 1907. Serial No. 361,829.

T 0 all'who'm it may concern Be it known that I, GE

siding at Minneapo is, in the-county of Hennepin and State ofMinnesota, have mvented certain new and useful Improve ments in Plated Metallic Bodies; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable othersskilled in the art .to which it appertains tomake and use thesame. Y

My invention has for its object to provide a plated metallic body which will be" efiicient to resist corrosion under the'action of.

the elements to which said productis naturally exposed in use.

To th1s end, my invention consists of a plated metallic body having the character.

istic features hereinafter described an pointed out in the claim.

Iron, using this term in its broadest sense, so as to include steel, and all similar metals, is the body primarily intended to be plated, but the invention may be realized, possibly, with other metal-as the body'to be plated. The body to be plated may be in the form or shape of sheet metal, wire, rods, or any other of the manifold forms ordinarily taken by iron and steel for commercial use. Iron plated with tin is commercially known as tin-plate; iron coated with an alloy of tin and lead is known as terne-plate; and iron coated with zinc is known. as galvanized iron. This improved product has been commercially produced by the process disclosed and broadly claimed in my United States re-issued Patent, No. 12,779, of date April 14, 1908.

Considered as plat-ings for iron, all the above noted plating metals have some good qualities and some bad qualities; but none of the good qualities are common to all and none of the bad qualities are common to all. What is good in. one is lacking in another. No plating metal is good unless it will resist the elements to which the plated body is necessarily exposed in use; and none is good unless it is electro-positive in respect to the body plated thereby. Prior to my invention herein disclosed, no plated body existed, so far as I know, having these two GSSi'ltlEll qualities combined.

It is well known, in electro-metallurgy,

that different metals exhibit a dilference in A. Gooosox, a subject of the Kin of. Great Britain, re-.

and zinc is electro-positive.

electric'potential with respect- .to one another, when connected together under proper conditions to develop galvanic action.

other words, all the di erent metals are, to

some extent, positive or negative with respect to one another, and the tendency of the galvanic action is to decompose the positive element only.

With reference to iron,-tin, lead and the alloys of tin and lead, are electro-negat-iye; The negative group of plating'imetals, above'noted, particularly lead, have great power to resist the action of the acids andother elements found in the atmosphere and in water. Commercially, however, it has been found impracticable to apply :"plating metals to iron in such a way as to make an'absolutely perfect covering of the iron. in practice,- that, ordinarily, there will be left more or less minute uncovered'spots It has been found,

of .the iron which, commercially, are called pm holes. Because of this imperfect cover; 1

ing, o r the presence of these minute pin holes, 1f iron be plated with any of the negative group of plating metals above noted, an adverse galvanic action will take place between the iron and the coating, metal, when the product is exposed to the elements, as it naturally is, in use. The bare or exposed iron, under the effect thereon of the acids in the atmosphere or water, or from other sources, will corrode or rust; and this corrosion or rusting will be greatlyintensified, at these uncovered spots or pin holes,by the adverse galvanic action, and this intensified decomposition of the iron, or rusting 'action, will be made quickly manifest by the deposition of the rust over large areas of the plating metal. For the above stated reasons, iron coated with said nega-.

tive metals, is not durable, in service, unless painted. This is a well known and generally recognized fact.

Zinc ishighly positive to iron; and, for

this reason, the galvanic action set up is favorable and protective to the iron; and, iron coated with zinc, although exposed to the elements, by thepresence of pin holes,

the result of imperfect coating, will not corrode so long as there 18 any of the zmc left. Zinc has anatural afiinity for iron and hence adheres well to the iron; and because of the said several reasons, above noted, has been extensively used for coating iron.

Zinc, however, will not withstand the. action of acids, but is rapidly eaten up thereby;

and, hence, a thin coating of zinc will notlastlong. Zinc must be applied to the iron in a comparatively thin coating; or, otherwise, it will scale off, because of-the brittleness of the zin For these reasons, 1ron coated with zinc shortlived underthe 'exposure incidenta to' 'use I ha ve made dlSCdXGIIGS which have-led me to employ, for! e plating metal,\ an alloy or chief component an' having as its 1 -Q-B g8 InetaL;;but also containing an 1 xo-. osi tiveametal in .sufiicient quantity to r'endhr e alloy electro-positive with respectjtothe ody plated thereby. So .far,

I haye usedt salloyfor plating iron or steel and find lat I get a product havin all the good qualities peculiar to the best o the 'negati e metals above named, -.to -jwit, lead,

together, with the essential or protective quality .peculiar:t othe positive metals. So far,

in-praetice, I have employed leadalone, or

lead and tin together, as .the'base orchief component of the alloy, "and put therewith sufiicient zinc to render .the' alloy electro-' positive to the iron. I have secured the best results with an alloy composed of about ninety-five per centofleadand five percent. ofzinc.. Attention may be here called to the fact that riorto my invention it was not deemed feasi le to form an alloy of lead'and zinc containingmore than-one and six-tenths per cent. of zinc whichsmall percentage of zinc is not suflicient to render the alloy electropositive .to iron. In. order toobtain' the necessary percentage of zinc in the alloy to render the negative metal, to wit,- lead, elecfire-positive. to iron, I find itconvenient to employ-the general mode of producing the 'coatingimetal described in my prior patent and application aforesaid. The electrified lead orbody of molten lead, when subjected to. an electric current, under the conditions specified in the patent and application aforesaid, readily alloys with percentages "ofzinc far in excess of those previouslydeemed possible and sufiicient, moreover, to render the alloy electro positive to iron, which condit-ion'I find maintains when'the content. ofzinc in the alloy is equal to approximately:

three per cent., and, of course, obtains for all higher percentages of zinc, lVith these alloys, I have produced a product which .successfully withstands the most severe humiditytest and an acid test more. severe than any found in actual-service.

Theusual-or customary test for galvanized iron, isto place a piece of the same. in a solution of sulfuric: acid, made up 'ofnineteen par s of water toone of acid, and leave the piece-of galvanized iron immersed therein for twenty-four hours. At theend of this time, under such a test, the zinc will be found to have entirely disap eared and the iron to be partly destroyed. 1y product, when subjected to this identical test, for the same length of "time, is found, at the endof the test, to be perfectly intact. I have even subjected my product to this test for severalspect to acids. The humidity. test is usually alforded by a moisture laden bath in which the plated article is suspended for twentyfour hours. Ordinaryterne-plate and ordinary tin-.plate, suspended in such abat-h, for twenty-four hours, will-develop the presence or absence of pin holes, or other, abrasions,

through which the iron is exposed to the action' of thebat-h. Otherwise stated, blotches of rust willbezdeveloped under the adverse galvanic action," in that short time, and be spread over the-plated surface so as to'be very manifest, if these pin holes or abrasions are present. Likewise, if the specimen has been cut froma larger plate, the edge will be rusted all around. -M 'product,.whe sub- 'ected.to such a humi ity test, even though purposely scored witha sharp instrument so as to exposethe iron, will not develop the slightest trace of rust, although left in the bath for a much longer time. For. example, ,I have left-specimens, scored so as to expose the iron, insucha humidity bath, for several weeks, andhave found that absolutely no rust developed. This fact is due to the favorable galvanic action,'andnot to any extra perfection or completeness of the covering. It will be seen, therefore, that my product withstands the two crucial tests which are customarily applied, respectively to the said positive and the-said negative group of .platmg metals. The positive group of plating metals do not require any humidity test, be cause the galvanic action is favorable; and, as above stated, the negative groupof plat ingmetals do not require any acid test, because their ability to withstand acids is well known.

; :It may-seem remarkable that an alloy composed of 95% of a metal or metals, which,

by themselves, are electromegative with respect tot-iron, andcontainingonly 5% ofa' metal, vwhich, by itself,l is .electro-posit-ive .with respect-to iron,;fs .houldmake the: alloy elect-ro-positivein resp c to. the iron coated thereby but my tests} completely demonstrate this to be'the fact-. The application" of an ordinary galvanometer to specimens of this -alloy andiron,'in a proper. bathgwill show that the alloy isdecidedlyelectro-post tive in respectto'theiron.

Of course, I do not limit myself to the exact proportions of the constituents of the alloy above noted. The point is to employ an alloy hating as its base or chief component a'large proportion of a metal or metals which is electro-negative and which alloy also contains a small pro ortion of an electro-positive metal in su lcient quantity to render the alloy electropositive with respect to the body to be plated thereby.

The invention is illustrated in the accom panying drawing.

The single figure is a View in section taken through the plated metallic body.

The numeral 1 indicates the metallic body and the numeral 2 indicates the material applied thereto.

What I claim is:

A metallic body plated with a homogene-.

ous metal alloy containing ninety per cent. or more of lead and ten per cent. or less of zinc,

the said zinc being suflicient to render said alloy electro positive in respect to the body plated thereby. v

In testimon whereof I affix mysignature in presence 0 two witnesses.

GEORGE A. GOODSON;

' lVitnesses:

JAB. F. Wnmmmson,

M. EVRONEY.

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