US2212271A - Coated fabricated metallic sheet - Google Patents

Description

Aug. 20,- 1940. H. KOH LI IR 2,212,271

COATED FABRICATED METALLIC SHEET Filed Marc]; 20, 1959 SHEET STEEL TIN-ZINC MERCUR Y AMALGAM COA TING SHEET STEEL 7 zuvc co ATlNs AMALGAM COATING F: g. 2

INVENTOR Henry L..Kohler TTORNEY Patented Aug. 20, 1940 UNITED STATES COATED FABRICATED METALIJC SHEET Henry L. Kohler, Kansas City, Mo., assignor to Andrew A. Kramer, Kansas City, Mo.

Application March 20, 1939', Serial No. 262,966

A 11 Claims. (01. 29-181) My invention relates to protective coated articles, and more particularly to coated fabricated metallic sheets, or sheet metal articles provided with a protective coating. This application is a continuation in part of my co-pending application Serial No. 160,803, filed August 25, 1937.

A difiiculty that has always existed in the util ization of galvanized metallic sheets for making certain articles out of the same, has been that the galvanizing coating is not suiliciently resistant to corrosion under certain ,conditions to make the practical use thereof possible. An attempt to overcome this difliculty has been made by providing a heavier galvanizing coating on the sheet.

The heavy'zinc coating thus provided, however, has the disadvantage that, when the sheet is bent, the coating at the bend would crack and tend to peel or flake ofi. As a result, although the sheet as a whole was provided with a heavy 2o galvanizing coating over its entire surface before being fabricated, the bending of a sheet to form a flange or a seam thereon, frequently damaged the galvanizing coating on the sheet so seriously that it would render the coating partially ineffec- 5 tive, on the outside of the bends required to form the flanges, or seams. Consequently the advantage of the heavy galvanizing coating on the sheet was largely lost, this being true because, at the point at which the galvanizing coating was caused to be damaged, or ruptured, by bending,

the sheet would be, for practical purposes, no better than an uncoated sheet, as far as resistance to oxidization, or other corrosion, was concerned. While many attempts have been made to overcome this difliculty, as by a hot dipping process after the article has been formed from the galvanized sheet, for example, this is' ditficult to accomplish and requires expensive equipment, if any large sheet metal article is to be galvanized after fabrication by such a dipping process.

' It is a purpose of my invention to provide means for overcoming the above mentioned difliculty with galvanized sheets that have a heavy coating of galvanizing thereon, providing a pro- 4 tective coating at the bend, or bends, in the fabricated sheet that will be even more resistant to corrosion, due to certain causes, than the galvanized sheet was priorto bending, and which will resist every kind of corrosion at least as well as did the galvanized sheet with the heavy galvanizing coating thereon prior to its fabrication, and also to provide a sheet thatis much more resistant to corrosion over the entire area thereof, if such resistance over such entire area is desired,

than is possible with ordinary zinc coatings provided by the usual galvanizing process. I preferably accomplish this by providing a tin-zincmercury amalgam coating on the sheet, which is applied to the area thereof that it is desired to give the better protection than can be given by 5 means of the heavy galvanizing coating usually provided.

My improved protective coating may be uti-. lized to give better protection than zinc against certain types of corrosion, or corrosion due to 10 certain causes, either over the entire area of a metallic sheet, or over the entire area of one side thereof, or over the entire area of a fabricated sheet metal section, or one side of such a section, if this should be desired, and is par- 15 ticularly adapted for use at and adjacent the bends in a fabrication sheet, whereby any rupture in the galvanizing coating that may have occurred during fabrication, from any of the fabrication steps, will be closed and the sheet protected at such bends, or other fabricated portions thereof, more effectively than was the case before the bending, or other operation, thereon, that damaged, or ruptured, the protective zinc coating on the sheet originally. 25

In galvanizing iron, or steel, the zinc forms a thin layer of ferrous zinc alloy immediately adjacent the steel or iron of the sheet, which has a much higher melting point than the spelter, or I, zinc, and immediately sets and thus prevents any 30 further alloying action between the zinc and the. iron of the steel. The remainder of the spelter forms a coating of almost pure zinc overlying the coating of ferrous zinc alloy on the sheet. This outer coating of zinc varies in thickness consid- 35 erably, depending on how it is applied to the sheet. Sheets are provided with a heavy coating of galvanizing by repeatedly dipping, or running the sheets through the galvanizing bath. This zinc coating does not have the tensile strength of steel, nor the flexibility of steel, and consequently when the sheet is bent the tendency is for the coating, particularly on the outer side of the bend in the sheet, to rupture, or crack, at least down to the ferrous zinc alloy that forms the innermost coating on the sheet. If nothing is done to rectify the rupture in the zinc coating after fabrication, such a heavy coated, or heavy galvanized sheet, will be subject to substantially as much corrosion at such ruptured point in the 50 coating as would be true if it had never been coated at that point. My invention entirely overcomesthis difiiculty and makes the bend, even though a rupture had occurred in the galvanizing coating in the fabrication of the sheet, more resistant to corrosion than was the case prior to fabrication, and particularly resistant to corrosion due to sulphur compounds present in certain oils and similar materials that may be confined in tanks that are manufactured out of galvanto fabrication of the sheet. Mercury may be re garded as semi-noble. metal, and is particularly resistant to corrosion, because it is not soluble in dilute sulphuric acid, hydrogen sulphide does not affect it as readily as it does zinc, and the amalgams of mercury take on the characteristics of mercury to the extent that these are also highly resistant to corrosion, particularly'to corrosion due to acids, such as dilute sulphuric acid, or other acids and compounds, that may be encountered in the use of fabricated galvanized sheets.

The mercury may be applied in the metallic form, but inasmuch as some difficulty is .encountered .in preventing loss of mercury because of its extremely mobile character, it is preferred that an amalgam be made of mercury with zinc,

tin, bismuth, lead, or any metal that freely dissolves in mercury, which is applied to the part to beprotected. Preferably, an amalgam of the consistency of putty is rubbed on the metal at the place where the same is to be protected, such as at a ruptured place in the coating on the sheet, which permits the excess to be removed with a cloth and thus saved for futureuse. It is.

of course, necessary to remove the zinc oxide,

the sheet, as obtained by the usual galvanizing process. Galvanized metallic sheets have a characteristic Spangled appearance. It is-highly desirable to maintain this spangled appearance of the sheets after my improved coating has.

been placed thereon. This is accomplished by utilizing a paste-like amalgam of mercury and a metal that readily amalgamates with mercury.

such as tin, which is applied to the sheet in a manner that the structural characteristics of the coating on .thesheet are not changed. Thus my invention provides a sheet that has substantially the same appearance as an ordinary galvanized sheet, but which will, after fabrication, have at least as good a protective coating thereon as it had before fabrication, and in most cases, a better protective coating. As the term -fabricati0n is used herein, it means any bending, cutting, or punching operation, or any other operation on the sheet, that may be performed thereon after the same has been rolled and galvanized.

It is a further purpose of my invention to provide a coating that will be substantially of the same hardness as the zinc coating usually provided on a sheet that is galvanized, this being accomplished by using the paste-like amalgam of such a composition and applied in such a manner that the amount of zinc and other metal, such as tin, in the final coating, will be such that it will have the desired hardness, even though the mercury is present therein. The presence of the mercury, however, gives the coating an extraordinarily greater amount of resistance to corrosion, due to the fact that the mercury content extends from the exposed surface 10 of .the coating inwardly toward and substantially to the metal forming the body of the sheet. Due to the presence of the mercury at the surface that is exposed to corrosion, any corrosive action that results due to sulphur compounds, or 15 any similar corrosive materials, that may come in contact with the surface. having my improved coating provided thereon, will result in the mercury being brought to the surface that is exposed in such quantity relative to the other ingredients of the coating composition, that the corrosive action will be effectively stopped. Thus the zinc in the coating at the exposed surface would be attacked to a certain extent by certain acids and sulphur compounds and would go into solution in the liquid that is in the tank, or other container, for which the sheets coated in accordance with my invention are particularly useful. However, when this occurs, the mercury content in the exposed surface portion of the coating becomes muchgreater in proportion to the other ingredients therein after the zinc is dissolved, and as the mercury will not go into solution, it forms a protective film over the exposedsurface, which stops any further corrosive action. While the tendency of the amalgam that is applied to produce thedesired coating is to penetrate the entire zinc coating of the sheet down to the steel, or to the ferrous zinc alloy coating next to the steel of the sheet, and appears to do this in all cases, yet even if such were not -the case, substantially the same result would be obtained, as the surfacethat is outermost and which is exposed to'the corrosive action does contain, for example, in the case where a tin-mercury amalgam is used, zinc, tin and mercury in such proportions that the mercury will produce the protective film as soon as even very slight loss of zinc occurs, and the tin being more resistant to corrosion than the zinc, not be lost, but will remain with the mercury at the exposed surface of the sheet. This protective film is, of course, very thin and the major portion of the coating will continue to exist as a tin-zincmercury amalgam coating, even though this protective film isformed.

Other objects and advantages of my invention will appear as the description of the drawing proceeds. I desire to have it understood, however, that I do not intend to limit myself to the particular details shown or described, except as defined in the claims.

In the drawing:

Fig. 1 is a fragmentary sectional view on a greatly enlarged scale, showing my improved amalgam coating applied to a sheet having a bend therein, and

Fig. 2 is a similar view, showing my'improved amalgam coating applied to a sheet otherwise fabricated than by bending.

and 2 the metallic body portion of the sheet is indicated by the numeral 3. The sheet shown in Fig. 1 is bent at 4 and the bend may cause damage to the coating of the sheet on the outer side 70 Referring in detail to the drawing, in Figs. 1

thereof. The zinc coating provided on the sheet is indicated by the numeral and the amalgam coating around the outside of the bend in the sheet is indicated in Fig. 1 by the numeral 6.

In Fig. 2 the same numerals are applied to the zinc coating and the amalgam coating, but instead of showing a sheet with a bend therein, the sheet is shown as being fabricated bypunching a hole I therein, this being merely illustrative of some fabrication operation that may be performed on the sheet.

My improved protective coating is provided on galvanized sheets that have been fabricated to the desired size and shape, by bending, die-shaping, cutting and punching operations, or any of these that may be necessary to produce the article, or sections of an article, of the desired shape from the galvanized sheet of metal. After the sheet has been fabricated, it is cleaned at the places at which the protective coating is to be provided thereon, usually by means of dilute hydrochloric acid, or a solution of tin chloride, or antimony chloride, or lead chloride, or zinc chloride, or cyanide of soda. This cleaning solution may be applied with a brush or swab of some character, and the excess may be removed with a cloth, or any other suitable means. When it is desired to apply the protective coating only at or adjacent a ruptured area on a galvanized sheet, or an area that may have been damaged to the extent of injuring the protective coating, or rupturing the same, the galvanized sheets are cleaned only on the outer sides of all bends therein, or any other area at which the coating may have been ruptured, or damaged, and areas adjacent these bends, or other areas where the damage may have occurred. A zone at the place at which the rupture in' the zinc coating may exist will thus be cleaned, and also a zone on each side thereof.

The mercury is then applied to the cleaned zone at the ruptured place in the coating and adjacent thereto, and in case metallic mercury is used, great care must be utilized to use only a small amount of the metal and to spread it by brushing, or otherwise-over a'large area of the clean surface of the sheet, so as to prevent any material loss of mercury' due to its rolling off the sheet because of its great mobility. The mercury, in being brushed over the sheet, particularly at the ruptured place, or zone, in the zinc coating will amalgamate with the zinc, forming a thin coating of mercury-zinc amalgam over the entire surface that has been cleaned,

with which the mercury comes in contact. At the rupture it will combine with the zinc that is broken away from the sheet, forming an amalgam therewith, which will adhere to the sheet closely and make a smooth coating, entirely closing up the break, or rupture, in the galvanized coating. If the right quantity of mercury is used, the amalgam thus formed will be somewhat moist at first and can be rubbed off with the fingers to a certain extent, but will gradually harden, and after several days, the sheet at the bend at which the mercury is applied, will have substantially the same appearance as the -remainder of the sheet and the amalgam will not rub off, even though the coating may be rubbed persistently for a considerable period of time. The coating thus formed will not be soluble in dilute sulphuric acid, nor in any other dilute acids, being only soluble in hot, concentrated sulv phuric acid.

As dilute sulphuric acid is ordinarily formed in oil tanks in which oils are stored that have a large sulphur content, my invention is particularly valuable for use in oil tanks that are made for the storage of such oils, which are commonly known as sour oils. Also many oils give off hydrogen sulphide, and in a moist atmosphere the sulphides of the metals are formed by the action of hydrogen sulphide on the metals. .Thus the zinc coating on a sheet in an atmosphere in which hydrogen sulphide and moisture is present, as will be the casein many tanks, particularly oil tanks, will be subjected to the combined action of the hydrogen sulphide and moisture, and transformed into a sulphide of zinc, which is readily soluble in dilute sulphuric acid. Where the zinc coating is ruptured, iron will be exposed and a sulphide of iron will be formed in a similar manner, by the action of hydrogen sulphide and moist air. On the other hand, sulphides of mercury, lead, tin and bismuth do not dissolve in dilute sulphuric acid. Also zinc and iron sulphides oxidize rapidly in moist air to form sulphates. Sulphides of mercury are fairly stable, and thus form a protective coating for the zinc. An amalgam of zinc and mercury will have largely the characteristics of the mercury, particularly as to its solubility, audits tendency to be acted on by dilute sulphuric acid and oxygen. It will thus be seen that by providing the amalgam of zinc with the mercury-in the manner above referred to, the sheet will be more resistant to corrosion, such as might occur in the use of fabricated galvanized sheets in commercial uses, such as the making of tanks, as, not only will the zinc coating be made more protective by the amalgamation with mercury, but the ruptured portion will be made more resistant to corrosion than was the case prior to bending of the sheet, when the zinc galvanizing coating was undamaged. As a matter of fact, tests made on galvanized sheets provided with my improved protective coating, utilizing the amalgamation of mercury with the zinc to produce the same, show that the portion of the sheet that is not ruptured and that has not been treated, but which has the full thickness of galvanizing coating thereon, will be attacked by dilute sulphuric acid and other means causing corrosion, whereas, the amalgam coated portion of the sheet will not in any manner be affected by'such corroding agents as would ordinarily occur in practice.

Instead of using 'metallic mercury, the amalgam coating can be formed with mercury amalgams. When a mercury amalgam is used, the cleaning step is carried out just as previously described, and after the cleaning of the area that is to be provided with the amalgam coating is completed, the mercury in the form of an amalgam, is applied. Preferably, the amalgam is made of the consistency of putty, so that it can be rubbed on the metal with substantially no loss of mercury. When this is done, the excess can be removed with a. cloth and saved for application to another sheet, or another portion of the sheet. Amalgams of mercury with zinc, or with tin, or with bismuth, or with lead, or with any metal that freely dissolves in mercury, can be used to make this putty or paste-like amalgam. Preferably, a tin-mercury amalgam is used to produce a sheet that has a tin-zinc-mercury protective coating thereon.

A putty-like amalgam of mercury and a metal readily dissolving therein, oramalgamatingtherewith, such as tin, is made up prior to cleaning the sheets, or is made up in quantity, to be used whenever necessary, said amalgam having such proportions of the metal, such as tin, and mercury therein, as to produce a, soft putty-like material I of a consistency of thick paste, or cream. The

proportions of mercury and the other metal amalgamating therewith that are used to produce this soft putty-like coating material, will vary with the metals used and with the atmospheric temperature existing, as the material must, of course, be of the soft, creamy putty-like character at the temperature at which it is applied to the sheet. Thus in the winter time, when a lower temperature is encountered, both in the at-y part by weight of tin to two parts by weight of mercury, and that, if exceedingly low temperatures are encountered, even one part by weight of tin to three parts by weight of mercury are desirable. The relative proportions of the metal amalgamating with the mercury that have to be utilized, are dependent upon the melting points of the metals that are amalgamated with the mercury, and the temperature encountered; Thus, if the mercury is heated, when the tin is added thereto, as much as fifty-five per cent tin can be included in the putty-like amalgam.

In making up the putty-like, or creamy, pastelike amalgam, it is necessary that the metal that is to be dissolved in the mercury, or amalgamated therewith, is in a finely divided condition when it is to be amalgamated with the mercury. The tin, or similar metal, can be in the form of ,any small particles, such as shavings, turnings, cuttings, or in the form of a powder or granules. The finely divided tin, or similar metal, is stirred into the quantity of mercury that is to be utilized to make the amalgam in the proportions necessary substantially within the limits above referred to. At ordinary room temperatures, it is unnecessary to heat the mercury to cause the tin to be dissolved, unless a relatively large quantity of tin is to be incorporated in the amalgam. After a thorough stirring of the finely divided tin in the mercury, the amalgam is formed. However, if

low temperatures are encountered, at which themercury will have a more sluggish character, and f at which the amalgamation will not as readily occur, or in case it is desired to speed up the amalgamation of the mercury and the tin, or similar metal, or increase the proportion of tin to be included in the putty, above that readily amalgamating with the mercury at room temperature, the mercury may be heated for this purpose, keeping the temperature of the mercury well below that at which it would vaporize.

The soft-putty-like amalgam of tin and mercury produced as referred to above, is applied to the cleaned area, or zone, of the galvanized sheet, by brushing or rubbing the same onto the cleaned area of the sheet with a cloth, or similar in her, this rubbing or brushing operation spreadr g the tin-mercury amalgam over the cleaned area of the sheet and causing a thin layer thereof to adhere to the outer surface oflthe zinc coating on the sheet, and in case there is a rupture or damaged area in the sheet, from which the zinc has been entirely, or substantially entirely, re-

the sheet at this point also. As soon as the tinmercury amalgam contacts the zinc coating on the sheet, it begins to react therewith to amal gamate the zinc in the zinc coating with some of the mercury in the tin-mercury amalgam. Accordingly, in brushing the amalgam back and forth over the ruptured area, some of the zinc of the galvanizing coating will be caused to be spread over the ruptured area, and any loose flakes or particles of zinc will be dissolved in the tin-mercury amalgam, amalgamating with the mercury therein.

The action between the zinc and the tin-mercury amalgam will-continue until the tin-mercury amalgam has penetrated the entire zinc coating of the sheet down to, at least, the ferrous zinc alloy at the surface of the iron or steel of the sheet. After the zinc is amalgamated with the mercury, the resulting amalgam that is produced will gradually become stiffer and harder, as the greater the amount of other metal amalgamated with the mercury; the harder or stifier the amalgam will become. As a result, the penetration of the zinc by the mercury-tin amalgam will eventually produce a zinc-tin-mercury amalgam protective coating on the sheet over the entire surface to which the tin-mercury amalgam has been applied, which has lost the soft character of the tin-mercury amalgam and will become as hard as the zinc coating originally on the sheet.

Thus'the amalgam, when first placed on the .sheet treated in the above manner, will be soft enough that it can be rubbed off on the fingers to a certain extent, and after at least twenty-four hours the coating at the area to which the amalgam has been applied will be hard enough that none of the same will rub off and the sheet can be handled without any damage to the amalgam coating, just as readily as was the case with the zinc coating originally on the sheet. Also, after several days the sheet will have substantially the same appearance as it did before any amalgam was applied thereto, and none of the coating can be rubbed off, even though it may be rubbed persistently for a considerable period of time. The action of dilute sulphuric acid and other dilute acids, on the zinc and tin will be retarded to such an'extent that the amalgamated galvanized sheet produced by my method, can be successfully used where an ordinary galvanized sheet would have such a short life that its use would be impractical.

While my improved coating is particularly adapted for use to prevent corrosion at ruptures or other sulphur compounds, which are ordinarily found in oil tanks, or similar receptacles. These sulphur compounds cause a corrosive action on the zinc coating of the'sheet as ordinarily provided in oil and similar tanks. However, by utilizing my protective coating, including the tinmercury amalgam, and applying it to the inner moved, the tin-mercury amalgam will adhere to surface of an oil tank, or the sections of an oil tank, made up of sheets that have been bent, cut and punched, this undesirable corrosive, action is avoided entirely.

The tendency of the sulphur compounds, when acting on the zinc-tin-mercury amalgam coating, is to cause the mercury in the amalgam to form a protective film on the surface that is exposed to the action of the dilute sulphuric acid, or hydrogen sulphide, or other sulphur compounds, this causing some slight loss of some of the other metals from the coating, such as the zinc and tin, but the mercury arresting this loss substantially immediately, due to the film forming action that it has.

There is substantially no loss of mercury in the carrying out of my method, because, if there is any excess of amalgam applied to the sheet, such excess can be removed with a cloth, such as the cloth by means of which the putty-like amalgam has been rubbed on the sheet, and the part thus removed saved for use on another sheet or other portion of the sheet. While it is immaterial whether the amalgam coating is of the same composition throughout, it has been found that if the soft putty-like tin-mercury amalgam, above referred to, is utilized, some of the mercury'in the tin-mercury amalgam will amalgamate with the zinc immediately, forming a zinc-tin-mercury amalgam, and some of the tin-mercury amalgam will be present without any zinc in it at first, this being on the top surface of the coating. However, if the tin-mercury amalgam is left in contact with the zinc coating for twenty-four hours or more, and an excessive amount of the tin-mercury amalgam is not'used, suflicient of the mercury will amalgamate with the zinc that all of the zinc will become amalgamated with mercury, and the resulting coating will be a tin-zinc-mercury amalgam, from the outer surface thereof to at least the ferrous zinc alloy at the surface of the metal of the sheet. Due to the fact that the zinc requires a much larger amount of mercury to be amalgamated with the same to produce a soft putty-like amalgam, than does the tin, this amalgamation of the mercury with the zinc, when completed,

causes the coating to have a hard character, similar to that of the zinc, instead of a soft putty-like character, such as the tin-mercury amalgam had before it was applied to the sheet.

The application of the putty-like tin-mercury amalgam to the sheet that has previously been galvanized results in the dissolving of the zinc on the sheet in the mercury of the tin-mercury amalgam, but the resulting liquefaction of the coating material on the sheet takes place through the thickness of the zinc coating thereon at such a slow rate that the structure of the zinc coating on the sheet is not altered, although the composition changes from substantially pure 'zinc to a zinc-tin mercury amalgam as the amalgamating process proceeds through tlie\coating. As a result the characteristic spangles of the galvanized sheet remain after the amalg mation is completed, the sheet having substan ially the same appearance two or three days,after the amalgam has been applied thereto as it had before any application of amalgam was made thereto.

When a putty-like amalgam containing 40% tin and 60% mercury by weight is utilized for application to a galvanized sheet that has a coating thereon of zinc that amounts to one ounce per square running foot, or one-half ounce per square foot surface on each side of the sheet, the amalgam resulting will contain approximately 65.8% zinc, 13.7% tin, and 20.5% mercury. With heavier coatings of zinc the percentage of zinc will, of course, be higher, and of course, the percentage of tin will be less where an amalgam containing a larger percentage of mercury is utilized. Galvanized sheets with coatings as heavy as two and one-half ounces per running foot are manufactured, and if the 10 above mentioned amalgam is-applied to such a heavily galvanized sheet, an amalgam coating containing 79.2% zinc, 8.3% tin, and 12.5% mercury will result. As in all cases the amount of zinc in the amalgam will be over 50%, the coating will not lose the characteristics of a zinc coating completely, but will be modified in its corrosion resisting characteristics to a considerable extent by the mercury contained therein, and to a lesser extent by the tin contained therein.

desired results obtained. As the putty-like amalgam is added to the coating on the sheet, none of the zinc is lost, but the tin and mercury is added thereto.

What I claim is:

1. A fabricated steel sheet having a zinc galvanizing coating thereon, said zinc coating having interruptions therein, and a coating of a mercury amalgam over and adjacent the interruptions in said zinc coating, said amalgam including zinc, mercury and another metal that freely dissolves in mercury, containing a much greater proportion of zinc than either mercury or said other metal and extending to the exposed surface of said coating and having at least as great a proportion of mercury therein at its exposed surface as adjacent the metal of the sheet.

2. A fabricated galvanized metallic sheet having a coating thereon of an amalgam of zinc,tin and mercury, said coating having at least as great a proportion of mercury therein at its exposed surface as adjacent the metal of the sheet, said coating having in excess of 50% zinc therein.

3. A fabricated steel sheet having a zinc galvanizing coating thereon, said zinc coating having interruptions therein, and a coating of an amal gam that includes zinc, tin and mercury thereon" over and adjacent theinterruptions in said zinc coating, said amalgam coating having at least as great a proportion of mercury therein having a bend therein, an amalgam protective coating over and adjacent said bend, said amal-,

gam including zinc, mercury and tin, said amalgam coating having at least as much mercury therein at the exposed surface thereof as adjacent the metal of said sheet, and having more zinc than tin and mercury therein.

' 6. In. a fabricated galvanized metallic sheet having a bend therein, a zinc coating having an interruption therein on the outside of said bend H "on the other side thereof, said amalgam extending to the exposed surface of said coating and having at least as great a proportion of mercury therein at its exposed surface as adjacent the metal of said sheet, said amalgam having in excess of zinc therein.

8. A fabricated galvanized metallic sheet having a bend therein, said sheet having a coating of only zinc on the inside of said bend and a coating of an amalgam including zinc, mercury and another metal that freely dissolves in mercury on the other side of said sheet over and adjacent the outside of said bend, said amalgam extending to the exposed surface of said coating and having at least as great a proportion of mercury therein at its exposed surface as adjacent the metal of said sheet, said amalgam having vin excess of 50% zinc therein.

9. A fabricated metallic sheet having a coating I thereon of an amalgam including from to 80% zinc by weight, tin and mercury, said coating having at least as great a proportion of mercury at its exposed surface as adjacent the metal I 'least as great a proportion of mercury at its exposed surface as adjacent the metal of the sheet.

11. A fabricated galvanized metallic sheet having a coating thereon of an amalgam including from 9% to 26% mercury by weight, from 45% to as much tin as mercury by weight and in excess of 50% zinc by weight, said coating having at least as great a proportion of mercury at its exposed surface as adjacent the metal of the sheet and having the spangled appearance of a sheet having a galvanized coating.

5:1 1:11 L. KO.

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