US78786A - Edwabd l - Google Patents

Description

Hire.

Letters Patent No. 78,786,dated June'li,'1868.

lld'PBOVBD PROCESS DP COMBINING WBOUGHT AND CAST METAL flit: Stimuli return to a time Esters fittest no mating not of lip same.

Be it known that I, Enwsnn L.- Bnowu, of the city of Philadelphia, State of Pennsylvania, United States of America, have discovered a new and useful Metallurgical Process for use in the-mechanic arts.

, In order to enable the public tmunderstand the nature of my invention, and those skilled in the arts to use the some, -I describe it as follows: I i l Wrought metal is valuable in castings on account of its tensile strength, the tensile strength of wrought metal being nearly double that of cast metal. In efforts that have hitherto been niade to introduce wrought metal into castings, for the purpose of imparting to them additional strength .to resistvarious strains or concussions, the wrought metal has been first coated with tin, or some other metal easily fusible, to act, first, as a solder or'means of union between the wrought and cast metal, and, second, to absorb a part of the heat of the cast, metal, and thus prevent the crystallization or granulation of the wrought metal.

The use, in this connection, of a metal,.or alloys of metal easily fusible, is, I, believe, valuelcss; indeed worse than than positively injurious, and for the following reasons:

It is unnecessary as a solder, for by my process the cast metal shrinks closely around the wrought metal, and forms a perfectly tight joint, and the compact combination of the metals isalso further secured, as hereinafter mentioned. In order to have the fusible metal act as a solder, a considerable thickness of it must he used.

and thus a layeroi' comparatively weaker metal, either the solder alone or the solder alloyed with the cast metal, mustnecessarily intervene between the wrought metal and the body of the cast metal.

The fusible metal or alloy, acting as a solder, docs absorb some of the heat of the molten cast metal, but in so doing it melts, and allows the cast metal at a heat only slightly diminished to come in contact with the wrought metal. This melting of the fusible metal produces various injurious results The wrought mctal,.undr the influence of the heat of'the cast metal in contact with it, is crystallized either entirely or partially, and its fibre commcnsurately destroyed, and to a degree suflicieut to materially reduce its tensile strength.

The tin or other fusible metal or alloy in melting is chemically decomposed, and a gas or gases generated, which, being very volatile and elastic, must expand. and force theirway into or through the molten metal. These gases generally showing their cheats on the cope or upward side of the casting, force their way either entirely through the casting, thus-forming blow-holes, visible from the outside, or partially through the costing,

not discernible till the casting be broken When broken, these castings present a honey-combed or spongy appearance, full of cells and holcs'of irregular shape, caused by the gases generated as above mentioned, and for this reason it is utterly impossible, as I believe, to make a solid compound casting with the use of any fusible metal, or alloys of metal, as a coating for the wrought metal.

If wrought metal be used without anycoating, either heated or cold, polished or unpolished, the molten metal, by its heat, decomposes the oxide of iron, which, it is well known, is always present on all iron in a greater or lessdegrcc, and releases th oxygen gas. This gas forces itsclfinto or through the casting in a similar manner as the gas generated from the fusible metal or alloy, as above mentioned, and causes the casting to present a similar appearance of honey-combing or sponge.

All these gases, whether evolved from th' oxide of the wrought metal, or from the decomposition of the fusible metal, act as an elastic cushion, and prevent the close shrinkage of the cast metal around the wrought metal. v

The true solution of the problem, which I claim to have discovered from my extensive researches and experiments, is this: f

To present to the molten match-instead of an easily fusible metallic surface, and one thus readily resolved by heat, a metal, alloy of metal, or metallic or mineral substance, difiicult orimpossible to melt at the degree ing is a description of my process:

' That all iron, though perfectly cleansed, is very easily, indeed almost instantaneously oxidized by expo of the heat of the molten metal poured about I thus secureimportant and essential results, and the follow-.

sure to the atmosphere, and that the presence of a high heat on an oxidized surface releases the oxygen gas, and that oxygengas is very volatile and elastic, are well-known facts. It is also true'that the action of molten metal at a great heat on any easily-fusible metal, or on any metal fusible at a less degreeof heat than the molten metal, evolvesfrom that'fus'ible metal, when heatcdto the point of fusion, a volatile and elastic gas... It is, therefore, essential, in order to produce a solid castingcombined of wrought and cast metal, to prevent the formation of these'oxyge'n or other gases during the process ofcasting. To accomplish this result I first thoroughly. cleanse the wrought metal, by use of'acids or otherwise, and immediately thereafter thoroughly and perfectly coat it with a non-oxidizable metal or substance v'ery difiicult to fuse. For this coating it is necessary to use a metal or substance that will-melt only atu higher heat than the cast metal that is to'be poured about it. I prefer to use nickel for this" purpose, as this melts only at an exceedingly high heat, much'j-higher than that of iron, and indeed is almost impossible to fuse. Other metals, suclias platinum, can boemployell, and I. believe that such nonoizidizable and non-conducting substances as plumbago can be successfully used for this coating. I

The wrought metal should be coated immediately after beiug' cleaned to prevent oxidation from taking place, and is covered-with its coating by means of afgalvanic battery or other electric action, or by means of heat or other chemical process.

In order to obtain a perfect coating of then on-fusiblc metal, the wrought metal must be very thoroughly cleansed, and itmay be first coated with copper, or other-metal for whichiron has agreat aflinity, to serve as a basis for the coating of the non-fusible metal. v a

The molten cast metal cannot, when it comes in contact in the mould with the wrought metal thus prepared,

' melt this coating, and cannot strike the wrought metal'itself. No gas can-be evolved either from thecoating or from the wrought metal. The cast metal shrinks closely and tightly about the wrought metal, andnotc'oining' v in contact with it, but with a coating that it cannot melt, that is not oxidizablc, and does not readily conduct heat, it cannot impair the fibre of the wrought metal, No gas being evolved, no blow-holes, honey-combing, or

' cells are'formed, and a perfect and solid casting is produced without difiiculty.

' My experiments justify the conclusion that neither gold, silver, copper, nor tin can he uscd forthis coating in iron manufacture, as they all melt, and consequently oxidize and generate gas, at. a much lower heat than" the cast metal. Only such metals, alloys, or substances can be uscdns' will not melt at the degrce'of heat required for casting metal. Y 7

By the process above described, the cast metal shrinks closely. about the wrought metal, and holdsit firmly without the intervention of: any solder. But to secure this result beyond any possible doubt, and prevent displacement under the heaviest concussions, before coating thewrought metal, I rag or barb'it with a.sl i'arp chisel, or otherwise roughen or corrugate it. About each of these points, projections, or irregularities, howcverjp'r duced, the cast metal flows, and they thus act as internal rivets. By this means the wrought metal is more firmly embedded than can be done by any solder;

. I believe that the above-described process of coating the wrought metal with a non-fusible metal or sub- .stance, is the exact opposite of all methods heretofore employed in the combinationof wrought and east metal in castings, and is the only one lay which solid castings, composed of wrought and cast metal, can be made.

Therefore, what I claim as new and useful, and what I desire -to secure by Letters Patent of the United States of America, isv v s 1. Preparing wrought metal for combining it with cast metal for castings of all descriptions, where great strength of any kind is required, by first thoroughly coating it, by galvanic action or other process, with nickel,

or any other metal or metals, alloys of metals, or metallic or mineral substances, or their alloys, not easily oxidizab'le and vcry difiicult to fuse, and which only melt, or whosepoint of fusion is at a higher degree of heat than the molten cast metal to bepoured about it, the whole substantially us-aboye described.

2. Theproduction of castings, strengthenedbythointroduetiomof wrought metal coated with a metal, alloy of metals, or substance less fusible than the cast metal, substantially as above set forth.

' EDWD L. BROWN.

Witnesses:

JOHN J. Bananas,

TREADWELL CLEVELAND.