US1940678A - Process of treating alloys - Google Patents

Description

Patented Dec. 2 6,

Y UNITED STA TE'S PATENT OFFICE 1,940,678 PROCESS OF TREATINGALLOYS I'Jert E. Fisher and Malvin A Baernstein,

St. Louis, Mo., assignors to National Pigments and Chemical Company, St. Louis, Mo., a cor- Duration of Missouri No Drawing. I Application June 4,1931

Serial No. 542,096

r 8 Claims. (01. 75 -1) This invention relates generally to alloying of metals, and particularly to a process of forming alloys in which a material is added to. the mix for removing the impurities and preventing segregation of the constituent elements.

In the processes; of alloying metals whichhave been heretofore practiced, it hasbeen necessary in practically every instance to employ some material as a so-called flux. The function of the various fluxes which have been employed has been to increase the fluidity of the alloy by lowering to some extent the temperature of'fusion of the mixture. When the temperature of fusion is lowered by the addition of such a flux, it is apparent that the fluidity of the mix at a certain temperature will be substantially increased, andwith the fluidity thus increased the tendency of the various constituent elements to segregate one from the other is substantially decreased. With the fluxes which have been heretofore employed, however, it has been found that they had.v '2. deleterious effect upon the furnacesor' ladles' in which the alloy is made. The various fluxes which have been heretofore employed havebeen as a general rule extremely basic in character and accordingly have an unusual effect upon the walls 1 of the furnace or ladies as thecase may be.)

Among the objects of thisfinvention is to provide a suitable fluxing agent for use in the alloying of metals Whichwill not possess the disad; vantages of the fluxes heretofore known in corwhich roding or attacking thefurnace orla-dle in the alloy is compounded.

'In the processes which have been heretofore" employed in the making of alloys, it has been impossible'to prevent contamination of the alloyby foreign materials, such as are known as inclusions. For instance, in the various brasses someof the more common inclusions are silicon, aluminum and iron, and it has heretofore been impossible to remove these elements from'any alloy in which they exist as impurities or inclusions. Many other impurities are also prevalent in the various al loys, such as for instance, sulphur and phosphorus which in many instances have an extremely deleterious effect upon theultimate product'and which may be present either in their combined or free form. It is among the objects of this invention, therefore, to provide a material which may be added to an alloy mix and which will be effective to remove the various impurities or inclusions as well as expelling the occluded gases.

An object of this invention is to provide a process of-alloying metals which securesimproved results."-' l for usein the alloying of metals.

purifier :or cleanser. ment of this invention the material employed may limited to the use of the specificmaterial men- Another object is, to provide a fluxing agent for J a material for use in the making. of alloys which is adapted to expel various undesired elements I therefrom. a.

Othercbjects will become apparent to those skilled in the art when the following description is read: r

In accordance with this invention a material may be added to the mix of molten alloy while in the furnace or ladle in which it was compounded, which acts both as a fl'uxing medium and As an illustrative embodibe one known as tri-barium aluminate,

' '(3BaO-AlzOs),

which may be made in accordance with any suita ble wellknown process. It is to be distinctly. understood, however, that the invention is not tioned. I In alloying the various metals for making brass, it is usually necessary to employ some fluxing medium for lowering the temperature of plasticity thereof, or increasing the fluidity. of the mix at a certain temperature. In. accordance with the present invention a material "containing the oxides of barium and aluminum may be employed as such a flux and it has been found that such a material acts not only as a fluxing-agent, but also as a purifier and cleanser. The reason forthe purifying and cleansing action is to an extent at least from a theoretical standpoint, uncertain and it is, therefore, to be distinctly understood thatthe invention is not limited by any theoreti- 10o] cal discussion or reasoning which maybe given 7 for the purpose of illustration herein. I

When the compound, tri-barium 'faluminate, is added to the mass of molten metal the reaction which takes place is apparently due, in the first 165 p'lace,principally to the presence of barium, The barium apparently has a great afii'nity'for the I various inclusionsror impurities such as sulphur,

phosphorus and antimony, which are usually present in an alloy mix, such as for instance brass. 110

Moreover, in brass alloy, there is often present a small quantity of iron and silicon, as well as aluminum, and it is'apparent that the compound,

tri-barium aluminate, tends to throw off each of parently one of flocculation or coagulation, the,

tri-barium aluminate apparently tending to draw the various impurities out of solution and thus to increase the particle size thereof, by drawing together a great number of smaller particles into a single particle, or else by going into chemical com bination with the various impurities. At the same time the material has a fluxing action upon the alloy, tending to'increase the fluidity thereof at the existing temperature. In view 'of these two features the action which probably takes place upon the addition of the tri-barium aluminate to the alloy is simply one of decreasingthe resistance to the movement of the included particles, and thus accelerating the movement thereof towardthe surface where they may be oxidized and will remain as a scum or slag which may be readily removed in any suitable manner. It is-possible that some oxidation of the various inclusions may take place before reaching the surface due to the presence'of oxygen in the tribarium aluminate. The action of the alumina in the material is difiicult to determine, but it is evident that more beneficial results are obtained when the alumina is present than when barium oxide is used alone.

In the treatment of alloys with tri-barium aluminate as above described, the tendency of various constituent elements to segregate is substantially reduced. The reason, for "this is probably the great increase in the fluidity which is given the mix upon the addition of the tribarium aluminate, it being recognized the greater the fluidity of the mass, the less the tendency for segregation. Perhaps the same reason may be given for the fact that in alloys which have been so treated there is an absence of occluded gases; With the fluidity of the mass so greatly increased,

7 it is apparent that the resistance to the movement'of gas bubbles toward the surface is substantially decreased so that the bubbles of cocluded gases may readily move toward the surface and there be released. 7

sulphur and phosphorus from any alloy whether it be brass, a lead and. tin alloy,'an alloy of aluminum, a so-called base alloy or any otherof the various alloys in which the antimony, sulphur and phosphorus are recognized as impurities.

I Moreover, the tri-barium aluminate has no corro sive effects upon the walls of the furnace or ladle and .in fact acts as a cleanser therefor.

"The various constituent elements of the fluxing and purifying material may, however, be deposited in the alloys in other compounds than i that just discussed. For instance, a compound known as sodium barium aluminate and having a formula, I (BBaO-AlzOa) (NazO-AlzOaLjwhich may be and preferably is made in accordance with the process disclosed in the copending application of Elbert E. Fisher, SerialNo. 537,201, filed May 13, 1931 may be used, but it is to be distinctly understood that the invention is not ascum or slag; The scum or slag may be From the foregoing description it is apparent as are made by the process described in the aforementioned application. Such a material as sodium barium aluminate contains all the constituents of tri barium aluminate hereinbefore discussed and in addition thereto contains a substantial portion of sodiumpxide. Under some circumstances it has been found that the presence of sodium is extremely beneficial, while under. other circumstances the sodium content is of little or no importance. In general it is believed that the action of the sodium barium aluminate upon an alloy is in most respects the same as the action of the tri-barium aluminate although as above stated under some circumstances it has been found that the presence of sodium improves the. action of the material both as a fluxing agent and a purifier. The reason for this improvement is, however, from a theoretical standpoint unexplainable.

It is apparent that when such a material as 95 tri-barium aluminate, or sodium barium aluminate is employed as a fluxing and purifying agent in the alloying of metals, the occluded gases may readily move thru the molten mass and be expelled at the surface, and the various solid particles of inclusions may also readily move toward the surface where some will be to some extent oxidized and all the various impurities or inclusions will beheld upon the surface of the alloy M5 raked or scraped from the surface of the alloy by any suitable means. At the same time the fluidity of the alloy is so increased that the tendency of the constituent elements to segregate one from the other is substantially overcome and a homogeneous solution is thus maintained so that the ultimate product is not only free from occluded gases and impurities, but is extremely homogeneous. v

g It is to be understood that the expressions"oxides of sodium barium and alumina, compound of barium sodiumand alumina, and fsodium barium aluminate are used herein and in the appended claims in their illustrative and not in their limitative senses. Where these expressions occur in the'claims it is to "be understood that those claims shall be construed of such scope as to cover equivalent materials.

that many modifications of this invention and m the material employed as a fiuxing and purifying medium will occur to those skilled in the art which will not depart from the spirit of this invention. It is to be distinctly understood, therefore, that the invention is not limited to the specific details which have been described and that such modifications thereof or the use of the process in the treatment of other alloys than those mentioned in the foregoing description,

which do not depart from the spirit of this invention, and although not specifically described here- .ingare contemplated by and within the scope of the appended claims.

Having thus described the invention, whatis claimed is: i V

1. In the art of alloying metals,'the process comprising, adding to the mix a material containing tribarium aluminate. 7 ,2. In the art of alloying metals, the process comprising, adding to the mix a material containing tribarium aluminate and an oxy-sodium compounds. V

,3. In the art of alloying metals, the process comprising, adding to the mix a material con- 150 sodium compound.

7. In the art of alloying metals, the process comprising, adding to the mix a. material con taining sodium barium aluminate.

8. A purifying and fluxing agent for alloys, .80

comprising, tribarium aluminate and an oxy- EL'BERT E. FISHER. MALVIN A. BAERNSTEIN.