US1939667A - Metallic coatings and method of making same - Google Patents

Description

Patented Dec. 19, 1933 UNITED STATES PATENT OFFICE METALLIC COATINGS AND METHOD OF MAKING SAME Henry Csanyi, New York, N. Y.

No Drawing. Application December 19, 1930 Serial No. 503,610

4 Claims.

ence of suitable assisting ingredients. The low melting point coating metals referred to are zinc or zinc alloys, notably alloys of zinc with lead and/or tin.

An object of the-invention is to produce such coatings on iron and the like which in the presence of moisture or water will "not become substantially corroded as heretofore with formation of zinc hydroxide. Briefly stated, my present invention substantially prevents this by incorporating barium, strontium and/or beryllium with the zinc or zinc alloy coating which I have found has the effect of preventing the wasting away of the zinc in the form of zinc hydroxide.

A further object of the invention is to prevent the cracking or flaking of zinc or zinc alloy coatings which takes place with zinc-coated iron,

especially when the coating is thick and is subjected to frequent bending or fiexure. With my invention, even a heavy plate of zinc or zinc alloy containing barium. strontium or beryllium constitutes a substantially non-cracking and nonflaking plating.

The following are preferred methods of procedure within and illustrative of my invention but without limiting the invention to the details thereof except as required by the appended claims in 86 view of. the prior art.

The surface of the sheet or article to be coated is first preferably freed from scale, oil and grease or other foreign substance by any well known treatment. I then brush, flow, spray or otherwise cover the iron or steel article or sheet (or other suitable metallic base melting well above the operating temperature of the process which is approximately 450 C. with a mixture which, when the coating metal is zinc or zinc alloy with a little tin, is made up preferably of the following ingredients in preferably approximately the following proportions by weight:

Per cent 0 Zinc powder (300 to 400 mesh) 77.5

5 Tin powder (300 to 400 mesh) 2.5

Zinc chloride 20 The foregoing well mixed ingredients are then further mixed with a liquid vehicle made up as follows: i

Per cent Water 80 Ammonium chloride 5 Barium, strontinum or beryllium chloride- 15 The proportions of the liquid vehicle to the aforesaid metallic powder mixture may be 40% by weight of the former to 60% of the latter. This mixture having been applied as aforesaid to the metallic article or sheet to be plated is then subjected to a suitable furnace heat at preferably 450 C. I may do this either immediately while the mixture due to the liquid vehicle is still wet; or I may allow it to dry or cause it to dry and then apply another layer or layers of the mixture in succession to the article or sheet. This procedure of building up a plurality of layers serves to increase the thickness of the resulting metallic coating on the article or sheet.

The furnace heat is applied for a period of time sumciently to melt the finely divided coating metals into an adherent coating on the article.

Another instance within the invention in illustration thereof serves to coat the sheet iron with a zinc-lead alloy with or without a small percentage of tin which will be substantially non-cracking and non-corroding in the presence of water due, as above, to the incorporation with the coating of barium, strontium or beryllium. The pro cedure oi carrying out the process is the same in this instance as before, the only change being in the formula or make-up of the ingredients of the metallic powder mixture which is now preferably as follows:

Per cent Lead powder (300 to 400 mesh) 45 Tin powder (300 to 400 mesh) 5 Zinc powder (300 to 400 mesh) 39 Amorphous red phosphorus 1 Zinc chloride 10 These ingredients having been thoroughly intermixed, the same liquid vehicle previously described is then mixed therewith in the proportions of about 50% by weight of each. The iron or other relatively high melting point metallic base coated as above with this mixture is then subjected to the furnace treatment to melt down the powdered metals into a coating on the base metal.

In this process, the lead must be kept free from oxide. For this purpose I prefer that the powdered lead ingredient should be mixed with 2% of finely powdered rosin or else moistened with an alcoholic solution of rosin consisting of 75% a1- cohol and 25% rosin. During the heat treatment for effecting the plating, the rosin powder or alcoholic rosin solution acts as a flux.

My present invention is an improvementon the invention of my pending U. S. patent application Serial No. 451,515 filed May 10, 1930, entitled Process of coating metals and composition therefor, wherein the reason for and mode of operation of the various ingredients is explained, such as the red phosphorus, zinc chloride, rosin, ammonium chloride, etc. My present invention diifers essentially from the foregoing by incorporating in the process a salt of barium, strontium and or beryllium, such as the chloride thereof, which becoming activated in connection with other ingredients in the process, results in the incorporation of the barium, strontium or beryllium with the zinc or zinc alloy coating to produce a plating which is substantially non-corrosive in the presence of water or moisture and which is substantially non-cracking and nonflaking.

The final operating temperature of approximately 450 C. referred to in the above description of the process is not critical but may be varied within the limits first of being sufilciently high to activate the vehicle and to melt the plating metal; and second, of being sufliciently low to be under the vaporizing point of the red phosphorus when the latter is employed.

The stated proportions of ingredients are preferred but nevertheless may vary considerably in any given case consistent with the described proper working of the process.

It will be understood that other changes and modifications may be made in the foregoing embodiments of the invention without departing from the scope or spirit of the invention as claimed.

What I claim is:

1. The method of coating iron or other high melting point metal with a coating of zinc or zinc alloy which comprises melting the plating metal in finely divided form in contact with the platereceiving metal, mixed with a liquid vehicle comprising ammonium chloride and a metallic chloride of the group consisting of barium, strontium, and beryllium chloride.

2. The method of coating iron or other high melting point metal with a coating of zinc or zinc alloy which comprises melting the plating metal in finely divided form in contact with the platereceiving metal, mixed with a liquid vehicle comprising ammonium chloride and a metallic chloride of the group consisting of barium, strontium, and beryllium chloride, and with zinc chloride.

3. The method of coating iron or other high melting point metal with a coating of zinc or zinc alloy which comprises melting the plating metal in finely divided form in contact with the platereceiving metal, mixed with an aqueous vehicle comprising ammonium chloride and a metallic chloride of the group consisting of barium, strontium, and beryllium chloride, and with zinc chloride.

4. The method of coating a metal base with a zinc alloy coating containing lead, which method comprises melting the coating metals in finely divided form on the metal base mixed with a liquid vehicle comprising ammonium chloride and 110 metallic chloride of the groupconsisting of barium, strontium, beryllium chloride, and also mixed with red phosphorus, rosin and zinc chloride.

HENRY CSANYI.