US1144523A - Metal-coating process. - Google Patents

Description

I No Drawing.

barren snares Ara orrica.

JAY G. BENEKER, OF CINCINNATI, OHIO.

METAL-COATING PROCESS.

To all whom it may concern:

Be it known that I, JAY C. BENEKER, a citizen of the United States, residing at- Cincinnati, in the county of Hamilton and State of Ohio, have invented certain new and useful Improvements in Metal-Coating Irocesses, of which the following is a specification containing such a full, clear, and exact description as will enableany one skilled in the art to use the same.

My invention deals with the art of'coating relatively corrosive metals with a protecting film; and it is concerned more especially with a method whereby a uniform and continuous film of lead or alloys thereof may be successfully and tenaciously applied to surfaces of iron.-

Heretofore sheet iron has been coated with tin forming what is technically known as terne plate, or more commonly'as tin plate; but owing to thehigh price of metallic tin, this material, while having many advantages, is quitecostly. In an effort to economize, the iron has been coated with zinc; forming what is currently lmown as galvanized iron, but not without the sacrifice of the superior physical and lasting qualities of the terne plate. The unsatisfactory features of galvanized iron have been well recognized, and therefore to find a commercially satisfactory way of producing a better substitute, and one less costly than tin plate, has been the goal for which those most skilled in the art have long striven.

I Now, this invention is based 'oncertain metallurgical and physical discoveries and an application thereof such that iron surfaces may be perfectly coated with a film of lead-or a lead-alloy so as most effectively to protect. the iron against corrosion, and at a relatively low cost and by a process en-' tirely feasible from the standpoint of all commercial requirements.

' Lead, as it is known to the commercial world, varies in cost depending upon its purity, 71. e., upon the amount of antimony with which it is alloyed. That is to say, .what is commonly known as hard lead contains a considerable amount of antimony,

while soft lead may be quite free of this common alloying metal. In .all its grades, this" metalleadis less costly than tin, while on the other hand it is vastly superior to zinc as a resistant to corrosion. By means of this invention, it is now made possible Specification of Letters Patent.

Patented June 29, 1915..

Application filed August 18, 1911. Serial No. 644,888.

perfectly to coat iron with such lead or its said alloys.

It has for long been recognized that lead is to a high degree proof against corrosion and this metal. has been rolled into sheets is necessary because otherwise they would not be of sufiicient strength to permit of handllng or servicelead being of little strength. Therefore, many efforts have hitherto been bent without success to produce on a sheet iron backing a tissue-like film of lead s0 uniformly and continuously as to avoid pin-holes or openings exposing the corrodible iron, and adhering with, such tenacity as to prevent blistering or separation, either byhandling or subsequent use.

By resorting to the method herein disclosed, those skilled in this art will be enabled perfectly to coat surfaces of iron with lead or its alloys, and to do so rapidly, eflectively and economically, and from every standpoint in a strictly practical and commercial way. In carrying out this process, the iron surface will first be cleared from scale and oxids in any suitable conventional manner, and is thereupon subjected to a suitable flux, preferably of zinc chlorid and submerged in a melted bath of lead containing a small proportion of cadmium. .I have discovered that lead in its various commercial grades, while ordinarily possessing little affinity for iron, will in the presence of metallic cadmium, even in very small quantities, amalgamate with the iron surface so as perfectlyto coat the same with a very thin film. Under ordinary practical working conditions where commercial considerations are paramount, I preferably use amounts of cadmium ranging from even so small an amount as .170 under excellent running conditions up to percentages as high as moderate expense will warrant, say 1% or over. Cadmium is in itself a very expensive metal, and therefore, from a commercial standpoint I prefer to use the smaller proportions thereof in the .bath. Inasmuch as cadmium, however, tends to oxidize and pass into the I flux (/which would .necessitate additions of cadmium to the bath to maintain the ininior preventive ofthis action the step of adding to the lead bath as much zinc as it will dissolve, say about Zinc being more readily oxidized than cadmium, it tends to pass into the flux in preference to the cadmium, and by adding the same, the more expensive metal may be conserved, especially when the bath contains considerable cadmium. A bath of this character has a. lower melting point than that of pure lead, which is a feature of great advantage, in that it enables palm oil fluxes to be used on the exit ends of the bath. This would be impossible in the case of zinc for example, as the palm oil would vaporize and burn at the high melting point of zinc.

Iron coated in accordance with this process possesses many advantages. The small proportion of cadmium in the film of lead, being a metal more positive than iron, tends to protect the iron in the same manner as zinc, and it exercises its positive features just as though it was unalloyed by reason of the fact that it exists as an element in a eutectic solution in the lead. This cadmium also has the important office of not only initially promoting the adherence of the lead film to the iron surface, but also of subsequently maintaining that condition. This coating is superior to zinc by reason of its very malleable character, so that in handling it does not tend to crack and open to-expo- 'sure portions of the underlying iron.

modifying, amplifying and inother ways i putting this invention into practice. I

- therefore intend that the terms used in the foregoing disclosure and in the accompanying claims are to be taken in a general, not in a special, sense. Thus, by the term lead ,,I contemplate the various grades of lead now commercially known, ranging from soft lead, of great purity, to hard lead, containing considerable amounts of antimony, for example.

I therefore claim as new and desire to secure by Letters Patent of the United States 1. A process of the nature disclosed for lead-coating iron surfaces, consisting in initially obtaining a clean iron surface, and then contacting the same with a fused leadbearing bath in the presence of metallic cadmium.

2. A process of the nature disclosed for I lead-coating iron surfaces, consisting in contacting the iron surfaces at an elevated temperature, with an alloy containing lead and a relatively small proportion of cadmium.

3. A process of the nature disclosed for lead-coating iron surfaces, consisting in oblead-coating iron surfaces, which consists in obtaining a melted bath of a commercial grade of lead and a small quantity of zinc and cadmium, and then subjecting the cleaned iron surfaces to said bath.

JAY 0. BEN EKER. Witnesses:

F. C. LAWsoN, G. H. BEAZELL,