US702050A - Method of removing scale oxid from the surface of iron or steel. - Google Patents

Description

252. COMPOSITIONS,

I ear [G h .irso s rn'rns 3- PATENT OFFICE.

METHOD OF REMOVING SCALE OXID FROM THE SURFACE OF IRON 0R STEEL.

SPECIFICATION runningpart of Letters Patent No. 702,050, dated June 10, 1902.

I I Application filed September 10, 1900. Serial No. 29,547. (No'speclmena) To all whom it may concern:

Be it known that I, ASAHEL K. EATON, of the borough of Brooklyn, county of Kings, and State of New York, have invented a new 5 and useful Method of Removing Scale Oxid from the Surface of Iron or Steel; and I hereby declare that the following is such a clear, full, and exact description of the same as will enable those skilled in the art to which my in- 110 vention pertains to use or practice the same.

In the removal of ha mmerascale, as it is called, from the surfacf of hammered or rolled iron or steel it has been customary to use.

lstrong corrosive acids, such 'ssulfuric, hy- "I5drochloric,' the. These acids efiect the de;'-

sired result at the expense, largely, of the underlying pure metal. This'is especially so in the treatment of the lighter articles of iron I and steel, such as wire br thin .plate. The

acid acts injuriously by the dissolving of the metal and consequent -loss thereof, and by molecular change of structure causes a brittleness and loss of thatelasticity and toughness which the metal exhibited before treatment. I therefore sought. for a substitute that would attack the mid only, leaving the underlying pure metal intact. I finally reached a satisfactory solution of the problem, which I will here describe.

The scale oxid found upon thesurface of all rolled or hammered iron or steel is represented by 'the chemical formulae FeO and Fe O thatis to say, a mixtu re,varyin gin different cases, of the protoxid and sesquipxjd of iron. It was desirable to find a compound which would readily dissolve these oxids without attacking the underlying surface. In eflfecting this 'it was necessary to devise a chemical combination which by first reducing the Fe O to the protoxid made the whole scale easily soluble, with the qualification that the solution or combination should be entirely neutral to the metallic surface beneath. I p

The agents which I have found to be most efficacious in carrying out my process are so lutions of sodium bisulfate and stannops chlorjd. Thsi'm'plest'afid"most economical m'dtlnod of producing this mixture I have found to be as follows I dissolve one hundred parts of sodium bisulfale in five hundred parts of water and tdthis add a solution of two parts 5551111 115 chlorid in thre parts of water. The result of this combination is by double decomposition a fluid consisting mostly of dissolved sodium bisulfate and a small portion of stannous siilfa'tbrwhich acts as'a reuuclm a cut of them hi 1" lzenso t esca e. epresented y cermc'a ormu ae,the reaction resultingfrom the mi re of the sodium bisulfate and the stann s chlorid isform of a protosalt, being an excellent 1;e

duciug agent, resolves the Fe,0,, constituent DRAFISMAN.

otthe sca e to FeO, thTareby rendering the I whole of the scale conipletely soluble in the extra acid constituent of the bi-acid salt. A

desirable feature connect''diviththis reaction is that while the solution of sodium'bi- 4, sulfate readily attacks the scale when thus reduced it has no pe cep f y or the ,1

bared metal. In order to prove this, I removed the scale of some thin steel, dried and weighed the metal,.and"then for three days left it in the solution. it was then dried and I weighed again, and I form 0 appreciable loss of weight. w I The time required in a cold fre solution 0 r hour. If the solution be heated, the time T: will be shortened to about five minutes.

for the removal of the scale is about half an The cold solution after being weakened by use requires a relatively. longer time or more or less heat to produce the same action in the same time; When the solution becomes weak, it may be improved by putting scraps of bright tin into the bath.

The same results could be obtained by the substitution of potas s i u in. bisulfate for, the

sodium salt; but the cost of this would be practically prohibitive. a The sodium bisulfate will by itself to a cer 2 a g 702,050 I tain degree remove the oxid; but as it attacks readily the protoxid constituent only it is not sufficiently rapid in its action.

Having now described my invention, what I claim is- 1. The method herein described of removing hammer-scale from iron or steel, which consists in treating the same with an agent to reduce the more insoluble ox'ids of the scale to a soluble condition, and with a solvent for the resulting oxid which does not injuriously attack the underlying metal, as set forth.

2. The method herein described of removing hammer-scale from iron or steel, which consists in subjecting the same to the simultaneous action of a reducing agent for the higher oxids, and a solvent of the lower oxids, in the form of a mikture of the solutions of the two agents, as set forth.

3. The method herein described of remov- 2o ing hammer-scale from iron or steel, which consists in immersing the iron in a bath containing a reducing agent for the higher oxids, and sodium bisulfate, as set forth.

4. The method herein described of removing hammer-scale from iron or steel, which consists in treating the same with a. bath containing in solution stannous sulfate and sodinm bisulfat-e, as set forth.

5. The method herein described of removing hammer-scale from iron or steel, which consists in subjecting the scale-coated metal to the action of a bath containing sodium bisulfate, as set forth.

A. K. EATON.

Witnesses: L. 0. SHERWOOD,

H. M. EATON.