US1297807A - Process of treating coated metals. - Google Patents

Description

WITED STATES PATENT OFFICE.

BRADLEY DEWEY, OF PITTSBURGH,

PENNSYLVANIA, ASSIGNOR TO AMERICAN SHEET & TIN PLATE COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF NEW JERSEY.

PROCESS OF TREATING COATED METALS.

No Drawing.

To all whom it may concern:

Be it known that I, BRADLEY DEWEY, a citizen of the United States, and resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Process of Treating Coated Metals, of which the following is a specification.

My invention relates to a process of treating metal coated metallic materials having an iron base, such as sheets and plates, pipes, tubes, nails, wire, and the like, and, while not restricted to such use, more particularly relates to a process of treating such materials after having been galvanized or coated with spelter.

The object of this invention is to provide a novel process of treating materials coated with another metal or a loy of metals by galvanizing or by any other method, whereby the materials are tight coated or coated in such manner as will permit the coated materials to be formed into shingles, metal window frames and other articles after such treatment, without causing the coating to flake off when subjected to the severe bending and pressing operations involved in making such articles.

The only method of commercially at coated materials relies upon its ability to produce the desired tight coating upon the application of an extremely small amount of spelter. This method, While making tight coated materials, makes a product which usually has inherentdisadvantages due to the presence of an abnormally large amount of lead in the galvanizing pot.

By treating galvanized materials, or materials coated in other ways, in accordance with my improved process, it is made possible to produce coated materials, having a bright, clean and relatively heavy coating of spelter or other metal or alloy of metals, but fully as tight or firmly adherent as the best quality of product-s heretofore made, having a much thinner or lighter Weight of coatingl.

As is well known, three distinct and well defined layers, comprising the steel base and the pure zinc outer layer of coating which are joined together by a layer composed of zinc iron alloys.

galvanizing practised Specification of Letters Patent.

present for making tight galvanized sheets have Patented Mar. 18, 1919.

Application filed December 12, 1912. Serial No. 736,302.

Under ordinary conditions the outer layer of zinc is tightly adherent to the zinc iron alloys forming the intermediate layer, but the layer of zinc iron alloys will readily separate from the steel base when subjected to severe bending such as being doubled upon itself, this intermediate stratum or layer of iron zinc alloys being hard and brittle and but weakly bound to the steel base forming the inner layer.

I have discovered that by heating galvanized or metal coated materials to a temperature ranging from about 410 to about 600 degrees Fahrenheit, and preferably between 420 and 575 degrees Fahrenheit and maintaining the heated materials at a temperature Within such range for a definite length of time, which time varies, depending upon the temperature to which the materials are heated and the rapidity with which such temperature is reached, that instead of being easily separated, the layer of zinc iron alloys and the steel or other metal base become very tightl bound one to the other.

This tightening action is believed to be due to the iron and zinc at the junction of the alloys layer and the basev gradually passing into solid solution in one another to a greater or lesser extent, in this way knitting the two layers together in such manner that a slight Vertical fracture through the coating no longer results in large flakes of the coating peeling off the materials, but at most shows an almost imperceptible roughness.

I have discovered also that when maintained for too long a time bet-ween the range of temperatures given, 4:10 to 600 degrees, the zinc or outer layer of the coating is caused to deteriorate and will then peel and flake off.

My invention consists in heating coated materials 3T0 a temperature having, in the case of spelter coated materials, an extreme range of 410 to 600 degrees, more desirably between 420 and 575 degrees, and preferably between 450 and 560 degrees Fahrenheit, and maintaining the materials between the high and low points in such ranges in temperature for a time interval varying inversely with the temperature at which the heated materials are held and of from ten minutes to as much as six hours in extent.

In carrying out the steps of my improved after being metal or alloy of metals in any known man ner, is placedwi'thin a muflie furnace and the temperature'of the materials is raised bythe application of heat. The temperature of the furnace is then regulated to heat the coated materials at a temperature of between 410 and 600 degrees Fahrenheit.

When materials are treated in accordance with my improved process immediately galvanized or coated it maybe found that the temperature of the materials when placed in the treating furnace will be higher than desired. In such cases, the temperature of th furnace will be regulated to reduce the temperature of the materials to that desired.

More desirably this range in temperature is restricted to between 420 and 57 5- degrees Fahrenheit, as the time interval in which the materials are maintained at a definite temperature with such ranges varies inversely with the temperature to which the materlals are heated.

With some classes of materials the range in temperature is preferably limited to the still narrower range of between 4:50 and 560 degrees Fahrenheit, but it is to be understood that my improved process may be car-- ried out when thecoated'materials are heated to a temperature-withn 410 and 600 degrees Fahrenheit and are maintained Within such range in temperatures for a time interval and are then allowed to cool.

In all cases care will be taken to heat the materials being treated uniformly.

The advantages of my improved process arise from the resulting tightening of the spelter coating or other coating material upon the material forming the base so as to obtain a metallic coating which is as tightly adherent as the best coated materials made .by the processes heretofore known, and in this way producing coated materials which are bright and clean and on which a heavy coating of any desired thickness or weight is obtainable.

The construction and arrangement of the furnace employed in carrying out my improved process may be modified in many ways. Means may be employed to create an air current or currents within the chamber of a mufile furnace in order to uniformly heat all portions of the materials placed within the furnace. The heating step may be found to be applicable directly instead of by conduction as in a muffle furnace, and other changesmay be made without departing from my invention as defined in the appended claims. I claim 1. The process of treating galvanized materials to tight coat the same, which consists in heating the coated materials to a temperature ranging from 410 to 600 degrees Fahrenheit, maintaining the materials at a temperature within said range for a time interval of from ten minutes to six hours, thecool.

3. The process of treating metal coated materials having an iron base which consists in heating the coated'materials to a temperature ranging from 450 to 560 degrees Fahrenheit, maintaining the materials at a temperature within such range for a time interval of from ten minutes to six hours, the time interval varying inversely with the temperature at which the materials are maintained, and then permitting the materials to cool.

4. The process of treating materials having an iron base coated with zinc to tight coat the same which consists in heating coated materialsto a temperature of at least 410'degrees Fahrenheit, holding the materials at such temperature for a t1me interval my hand. BRADLEY DEWEY.

and then permitting Witnesses:

CARL L. SCHUMANN, FRANK B. Comm.