US2065618A - Metal and method of producing the same - Google Patents

Description

Dec. 29, 1936. C, SHERWQOD 2,065,618

METAL AND METHOD OF PRODUCING THE SAME Filed Dec. 28, 1933 2 Sheets-Sheet l Dec. 29, 1936. c. F. sHERwooD 2,065,618

METAL AND METHOD OF PRODUCING THE SAME Filed Dec. 28, 193s z sheets-sheet 2 /35 I g Q2 5150' 32 30 I l l l l 35' 25 L Il 2.9 J 19 Q0 g3 Patented Dec. 29, 1936 UNITE-D STATES PATENT OFFICE METAL AND METHOD F PRODUCING THE SAME Delaware Application December Z8, 1933, Serial No. 704,283

13 Claims.

This invention relates to an improved metal l and method of producing the same.

The invention has especial reference to a metal for bearings and other articles having frictional surfaces, particularly engine pistons, valve guides, main bearings, and bearings of any form, and like articles, and is characterized by the formation of an oxide of iron packed into a briquetted shape and red to reduce the oxide to pure (or substantially pure) iron and of an open porous structure.

It is to be understood, however, that the metal of the present invention may be employed in all similar or equivalent articles, or elsewhere as suitable and desired, and its characteristics may vary within the scope of the appended claims.

The resulting product is a purer, more ductlle iron than can be commercially produced in any other way. It is of light weight and has a low coeiiicient of expansion. And it is of porous structure having minute communicating pores distributed throughout the mass.

The oxide of iron packed into a briquetted shape and fired to reduce the oxide to pure (or substantially pure) iron, and of an Open porous structure, particularly for bearings or other articles having frictional surfaces, is preferably impregnated with oil, and the metal so impregnated sweats or exudes oil when heated and takes in or absorbs it on cooling.

The present invention further provides for utilizing at least two sources of raw material, particularly either copperas or millscale" for the production of the present metal.

I prefer, however, making use of copperas, technically known as FeSO4. This is a Waste product usually obtained from pickling tanks or vats in the pickling of iron, steel sheets, wire, bars and the like. 'I'he disposal of this pickle liquid, after it becomes deficient in acid from the pickling operation, is a source of expense at the present time in the manufacture of sheet metal products. In a plant in full operation there are many tons per day of copperas which must be disposed of, in certain instances by hauling it from the plant in large wooden tanks on motor trucks to articial ponds a distance away into which the liquor is discarded as a waste product and allowed to settle and evaporate by solar evaporation. 'I'he cost of disposal of this pickle liquid is extremely high. There is, therefore, considerable economic advantage in my utiliza tion of this material.

The present invention also provides for producing commercial sulphuric acid as a by-product of the present invention. This is a further economic advantage of this particular aspect of the present invention.

It is to be understood, of course, that the present invention is not to be, limited to production of the present metal from the particular sources of raw material referred to herein and that I intend to cover the production of the present metal from all forms of iron oxide.

Further features and advantages will appear from the following detailed description taken in connection with the accompanying drawings, in which:

Figure l shows diagrammatically the several stages of the first step in the process;

Figure 2 shows diagrammatlcally the second step in the process;

Figure 3 shows diagrammatically an alternative second step which may be employed instead of the step shown in Figure 2;

Figure 4 shows diagrammatically the third step in the process;

Figure 5 shows diagrammatically the fourth step in the process;

Figure 6 shows diagrammatically the ilfth step in the process;

Figure 'I shows diagrammatically the sixth step in the process; and

Figure 8 shows diagrammatically the seventh and nal step.

I give the following examples of my process, but it will be understood that while in said examples I refer to certain sources of raw material and to certain articles formed of the metal of the present invention, the oxide of iron which I employ may be obtained from other sources, and the metal may be used in other articles. It will be understood further that the analysis of the product will vary according to the raw material used in its manufacture, and that the characteristics of the resulting product and the steps in the process may be varied considerably.

Where copperas or FeSO4, which is preferable, is used, the copperas is separated from the supernatant liquid by evaporation or careful crystallization as shown at 5 in Figure 1. Ferrous sulphate crystals 6 are thereby obtained having the formula FeSO4-|'7H2O. These crystals 6 are then dehydrated in a kiln, or by any method known in the art of moisture evaporation, as indicated at 1 in Figure 1, producing ferrous sulphate FeSO4 as indicated at 8.

'I'he ferrous sulphate is then calcined in a rotary kiln indicated diagrammatically at 9 in Figure 2, which kiln is preferably capable of being closed at both ends for purposes of driving off the sulphur content in the form of SO2 and S03. The temperature to which the kiln 9 is subjected should not, so far as I am now aware, be over 1800 F., and preferably should be between 1600 F. and 1800* F. This calcination in the kiln 9 is carried on until no visible fumes of sulphur are apparent. After the sulphur content is driven off, with the ends of the kiln 9 closed, city gas or, preferably, a reducing gas, such as can be made by the cracking of methanes and butanes, is admitted to the kiln 9 at I0, and the Fe203, which has been produced by the elimination of the sulphur from the copperas, or FeSOi, is reduced by this gas to FeO, more commonly known as black oxide, with a percentage of metallic iron.

It has been found that a percentage of 12% to 20% metallics can be obtained by using six cubic feet of gas per pound of FezOa in the kiln 9.

'The time element depends upon the size of the kiln and the rabbling effect obtained in the rotary action of the kiln. In producing 200 pounds of product, the time element for calcination or eliminating the sulphur would be approximately two and one-half hours. The time for reduction under gas from FezOa to FeO would be from forty-five to sixty minutes. The size of the kiln used in on' commercial adaptation of the invention is thirty inches in diameter and fifty-four inches long, red from the exterior, and rotating at 12 R. P. M., but this, of course, may be varied considerably.

The calcination of ores is common metallurgical practice, especially in zinc industries where sphalerite or zinc sulphide is calcined to zinc oxide. Kilns, known as Mathison and Hegler, Merton, Hereschoif, and Wedge, are used for this purpose. I make reference to these kilns as being suitable for this step of the present process.

I propose, in conjunction with the production of FeO containing metallics, that is, FeC-I-Fe, to make use of the SO2 and S03 which is produced during calcination and driven off at I2 in Figure 2 for the production of sulphuric acid. 'I'his can be done in the Well known chamber process or contact process, making use of a catalytic agent. These fumes being very dense and concentrated as they come from the kiln 9 at I2 are the same, in effect, as the burning of sulphur in the well known process of producing Vcommercial sulphuric acid. The economic advantage of this is that the sulphur obtained from this waste product is, at the present day, Worth $18.00 a ton.

In the above described kiln 9, after the period of reduction, the FeO plus metallics material is preferably allowed to cool under gas. This cooling of the material under gas preferably takes place in the kiln 9, and therefore constitutes merely another stage of the step shown 'in Figur 2 of the drawings.

Instead of reducing the FezOa to FeO and metallics by reduction under gas in the kiln 9, I cor template in practice using a shaft method of reduction, as shown diagrammatically in Figure 3, wherein the FezOa is cascaded in a shaft I5 through an ascending current of a reducing gas I6, which may be cracked methane, butane, or ordinary illuminating gas, as an alternative to the reduction under gas stage of the step shown in Figure 2. Such a method of reduction is well known in the art. The resulting material is, as before, FeO plus 12%" to 20% metallics.

This material, so obtained, is then ground to a ground or powdered form as indicated at I 9 in Figure 4, the grain size or degree of fineness of the ground particles varying with variations in the size of briquets I desire to make. In ordinary practice, for a. briquet of the class to be hereinafter described, this material is preferably ground so as to pass through an 80-mesh United States standard screen.

This finely ground or powdered material I8 is then mixed mechanically by a suitable mixer I9 with a small amount of binder material 20. This binder material may be a mixture of 50% ordinary turpentine rosin dissolved with heat in 50% petroleum jelly. The proportions are very seldom over 5% of binder in a total briquet. In some cases, depending upon the product which I wish to make, I also incorporate up to as high as 5% of finely divided carbon, such as petroleum lamp black, to produceCO and a more porous condition in the resulting product. My reason for using this is to accelerate reduction in firing the briquets to reduce the oxide to pure (or substantially pure) iron, which step of reduction will be hereinafter described. By using turpentine rosin I also get a nal amount of carbon from the rosin and also from the petroleum jelly to assist in the reduction.

In making use of binders in forming the material for briquetting, I have mentioned but one, that consisting of petroleum jelly and turpentine rosin, but I have used oil, water, glucose and foundry binders of all kinds, and no not wish to be construed as limiting the present invention to any particular type of binder.

It is oi importance that the FeO containing metallics be thoroughly mixed with the binder used and the lamp black, as they should be perfectly disseminated throughout the mass and of perfect mechanical mixture. It is desirable, therefore, that the mixing be carried out in a mixer of such type as will produce this result. Mixers of the sigma blade type are adaptable for this work.

The perfect mechanical mixture of iron oxide and graphite and/or lamp black (carbon) is then packed into a briquetted shape or article preferably by means of the high speed percussive briquetting method of my copending application filed December 28, 1933, Serial No. 704,284.

This high speed percussive briquetting method and the means therefor is shown in more or less diagrammatic form in Figure 6. It is to be understood that the brquetting means shown in the drawings is not necessarily the approved means, but merely illustrative of a suitable means in elementary form for carrying out the high speed percussive briquetting action which I employ.

The percussive or vibration briquetting device shown in Figure 6 comprises a rigid base 25 having positioned thereon a hardened steel mold 26. The mold 26 is preferably sectionalized radially at circumferentially spaced locations about the mold cavity 21 dened thereby, and the inner surfaces of the mold sections are preferably ground to form a smooth finished mold cavity defining surface.

The lower ends of the mold sections 26 are provided with integral flanges 28, the lowersurfaces of which are finished and seat upon the finished upper surface 29 of the base 25. Suitable clamping devices 30 cooperate with the flanges 28 to clamp the mold sections firmly in place upon the base 25, and the external surface 32 of the mold 26 is tapered upwardly from a larger diameter at the ange 28 to a smaller diameter at the upper end of the mold. A steel ring 33 may be interposed between the clamping devices 88 and the top of the flange 28, and a tapered steel holding ring 85 is slipped into place about the mold sections 28 to hold the mold sections firmly together and tightly closed about the mold cavity 21. 'I'he inner surface 38 of the continuous ring 35 is tapered from a larger diameter at the bottom to a smaller diameter at the top, this taper 36 corresponding to the taper 32 so that as the ring 35 is forced down over the mold sections the tapered surfaces will cooperate to bind and hold the mold sections together by a wedge-like action.

The particular means shown is for producing Yan annular briquette having a cylindrical external surface, at parallel ends, and a concentric opening such as is adaptable for use as a main bearing or any bearing, or as a valve guide or the like, and for that purpose is provided with an upright steel core 38. It is to be understood,

` however, that the core 38 may be omitted where a solid cylindrical body ls desired, and that the mold may be formed to produce a widarange of other shapes as suitable or desired.

The core 38 is disposed concentrically within the mold cavity 21, and may be positioned accordingly upon the base 25 by engagement of its lower end in a recess 88 in the upper surface of the base. A steel ring 48, the external diameter of which ts snugly within the mold cavity 21, is placed over the core 38 and down upon the base 25, and the mixture of iron oxide, graphite and/or lamp black (carbon) and binder is then placed in the mold cavity 21, down upon the ring 40, and around the core 38. A second steel ring 42 may be placed over the core 38 and into the mold cavity, down upon the top of the mixture, indicated generally at 43.

The driving head or ram 45 ts slidingly within the cavity 21 and is cored at 4B to operate slidingly over the upper end of the core 38. 'I'his driving head or ram 45 is rapidly vibrated by an air hammer, electric hammer, or other suitable means, indicated more or less diagrammatically at 48, and a reaction absorbing block 50, preferably in the form of an oak wood ring A inch thick is interposed between the steel ring 42 and the lower end of the driving head 45. This ring or block 58 may be of any other suitable or preferred material which will absorb the reactions to the rapid vibrations or percussive actions of the driving head 45.

In an illustrative embodiment of the invention,

'the vibration or percussion producing means 48 may be a 21/2 inch piston Ingersoll-Rand jack or air hammer, although other rapidly vibrated ramming or percussion devices are contemplated within the scope of the present invention.

The vibrations or percussions are rapid and, in one method of carrying out the invention, are of the order of about 800 to 1000 vibrations or percussions per minute. I find that this vibrating or percussive action produces rapid percussions in the material, and that this produces a briquet of homogeneous density and enables producing briquets as large as desired without laminations in or cracking of the structure of the briquet, and without variations in the structure from end to end, and particularly along the intermediate portions between the ends. This percussive briquetting method further makes it possible to produce the desired briquet formy of practically any size and of perfect homogeneity without excessive pressures and with an extremely low cost machine. For a briquet 2% inches in diameter in the forming of the briquets.

by 5 inches long with a 15h-inch opening and having a wall %inch in thickness, the material is filled in the mold to a length of about 12 inches. and is brought down to the 5-inch length by the vibration or percussive action above described.

In briquetting, the grain size is rather important. It has been found by various sizings that different densities of briquets can be made, so I do not wish to linut myself to any particular grain size in the formation of these briquets.

The accepted method at the present time of forming briquets from powders has been to use a hydraulic press, or high pressure mechanical presses such as the Colton press. Thesepresses make use of extremely high pressures usingas much as 35,000 to 75,800 pounds per square inch And it is impossible, in forming a briquet in a hydraulic press with a continuous application of the pressure,

to get a briquet of homogeneous density even wherethe pressure is applied from both ends of the mold or die. The resulting briquet, particularly if larger than that required for a relatively small bearing or bushing, is not homogeneous from end to end. 'Ihis has been established. By making use, however, of an extremely rapid percussive action I am able to make briquets of any size and any length, the only limiting factor being the size of the air cylinder or hammer used in the formation of the briquet. The more rapid the percussive action, the better the briquet.

'I'he cost of briquetting machines making use of extremely high pressures, either mechanically or hydraulically applied, has been extremely great. For example, to produce a briquet 2% inches in diameter by 5 inches long with a 11/2- inch opening and having a wall :3A-inch in thickness, it would take a hydraulic press capable of producing a ram pressure of not less than 600,000 pounds. Such a press would cost in the neighborhood of $45,000.00. I can produce these briquets with the percussive action referred to continually and rapidly at a total cost of equipment which is only a very small percentage oi' the cost above referred to.

The briquet 55 so obtained is then dried in a suitable drier 58 (Figure 7) at a temperature of from 300 F. up to 400 F., and then is of sumcient strength to withstand all mechanical handling from this step to the next step shown in Figure 8.

The briquet is then placed in a tubular retort 58, such as an 8-inch pipe with ll/z-inch openings 58 and 50, one at each end, to admit a reducing gas at 59 and allow the same to pass through the pipe 58 and be ignited at the outlet 80. The gas used at this stage of the process may be any of the reducing gases, such as hydrogen or illuminating gas. The retort 58 is then fired exteriorly. brought to a temperature of 1800 F.. and held at that temperature until all of the FeO in the briquet is reduced to pure or substantially pure metallic iron. This may be determined by taking periodical gas samples at the outlet 80 of the tube 58 and determining the CO2 content of the gas. It has been found that where an ordinary illuminating gas contains as much as 11/2% CO2 on admittance to the tube 58, a showing of 1.8% to 2% CO: at the outlet 80 is a very close indication that al of the oxide is reduced.

When the oxide has been reduced, the temperature in the pipe 58 is raised to about 2100 F. and held there for a period of approximately an hour. This temperature is maintained for this period for the purpose of sintering, and by the word Lsintering I mean that the metallic particles become soft enough below the melting point of iron to weld or coalesce one into another, producing thereby a porous structure of great mechanical strength. The briquet has minute communicating pores distributed throughout the body thereof. The period of sintering and the time of reduction varies with the size of briquet within the tube 58. As a typical example, the period of reduction would be approximately 2 hours and 20 minutes, and the period of sintering would be 45 minutes for reducing a briquet 1% inches in diameter with a 1 inch orice in the center, to a metallic sleeve such as would be adaptable for a shaft bearing.

I do not intend to be limited to the retort type of reduction, but contemplate using a contin uous moving hearth, either electrically or gas fired furnace. Similar furnaces 'are now in use for the welding of steel parts to copper in hydrogen or atmosphere.

The gas and temperature control during the period of reduction of the briquets is very .important. 'I'he type of gas used is of great importance as it is not desirable to use gas which cracks at high heat, thereby liberating excessive carbonaceous matter, as the same would contaminate the reduced iron and produce an unsatisfactory product. I do not wish, however, to limit myself to the exact temperatures or exact gases herein disclosed, as further experimentation may show that the same results may be obtained at a different temperature range, or with different gases.

By previously cracking butane before admitting it to the reduction retort it is possible to obtain a very-cheap and efficient gas for the purpose of reducing the iron oxide. During the process of reduction the carbonaceous material within the briquet is broken down by heat, and CO, or carbon monoxide, is liberated. 'Ihis gas is an extremely good reducing agent and assists materially in the reduction in the briquets, so that I really have two gases aiding the process of reduction, these being hydrogen and carbon monoxide. During the process of reduction, water is formed, and it is possible, by condensing this water, to use it as an indicator as to what stage the reduction has reached. This, together with the CO2 determination, gives rather accurate control of the reduction.v

After firing in the tube or retort 58, the briquet 55 is cooled under gas. In making use of the tube or retort 58, as soon as the period of reduction ofthe oxide of iron is over, the valve at the outlet end of the tube is closed and no further gas is used or consumed during the period of sintering or cooling.

The retort may be made of high temperature metals, such as chrome iron, or it can be manufactured very similar to the saggars now in use in many industries, or of refractory clays, carborundum, magnesite, or alundum.

A briquet produced in this manner can be controlled in size so as practically to need no machining to produce a finished article. Owing to the ductility of the metal so produced, it is perfectly feasible to give the final finish by a stamping operation, thereby eliminating all machining, although, of course, the article may be machined to size if desired.

The briquetting of the metal by rapid vibrations to produce percussive action causes the metal to fill and pack the mold even in intricate shapes, the material apparently flowing by the rapid vibrations or percussions caused by the rapping of the air hammer or the like. Intricate shapes may be formed.Y 'I'he nnal density depends upon the amount of rapping and the proportion of iron and graphite or other carbon in the mixture.

The briquetted and reduced mass, i. e., the porous iron mass is characterized by lightness, uniformity of porosity and ofdenslty and by a spongy structure. In metal made according to the prior process of sintering grains of metal, where powdered metal` is sintered, the structure consists of grains adhering or bonded to each other. Hence, fracture tends to occur across the joints or sintered bonds.

According to the present process, the resultant mass or end product is a unitary homogeneous mass which somewhat resembles a sea sponge in structure. The pores are of minute capillary size, and the walls which are all integral, being formed in situ, appear to be webs or lms merged into each other. The pores intercommunicate freely. The difference in structure is therefore pronounced,.and the difference in fracture shows the difference in structure. No loose grains are released by wear, cutting, or fracture, as is the case with sintered metal powder. Neither does the material of my invention tend to disintegrate into powder or particles upon being subjected to mechanical stresses.

Where the metal is to be used for bearings, pistons, or other structures having frictional surfaces it is desirable to impregnate it with a lubricant, preferably oil. The preferred method of doing this is under a vacuum, in hot oil, or in oil at a temperature of approximately 240 F., thereby insuring that there is no moisture present. In about twenty minutes, under a vacuum of 28 inches, the metal is thoroughly impregnated with any lubricating oil. This oil permeates through the intercommunicating pores of the structure and the metal so impregnated sweats or exudes oil when heated, and takes it in or absorbs it on cooling. The result of this is that where the metal is used in a bearing, bushing, valve guide, piston, or other part having a frictional surface, movable upon the surface of another part or upon which the surface of another part is movable, the lubrication of the cooperating surfaces is assured with the initial movement between such surfaces and without waiting, as in an internal combustion or Diesel engine, for a supply of oil to be sent up thereto.

By varying the density of the briquet and also by varying the amount of finely divided carbon which I incorporate in the briquet, I am able to produce a structure of varying degrees of porosity, running Afrom as low as 10% porosity to as high as porosity. During the process of reduction the percentage of metallics in the briquet increases the heat conductivity of the briquet and accelerates the reduction, thereby cutting down the period of time and producing a more coherent and mechanically stronger porous mass.

It is possible by the incorporation of other oxides in an admixture of FeO (iron oxide) to produce alloys of a porous structure such as a mixture of iron oxide and copper oxide, or a mixture of iron oxide and manganese oxide. It has even been found possible to make use of the highly difcult chromium oxide with iron oxide to produce porous alloys like the above.

The gas during the reduction period should be controlled so that large quantities of carbon are 75 not produced in the case of using illuminating gas for reduction, 'but it is contemplated in actual manufacture to make use of gas that has been cracked and contains very little carbonaceous material, as already described.

I have made use of FezOa in the formation of briquets and have reduced the same and produced a porous structure similar to that produced by the reduction of FeO, but the length of time necessary for reduction is so much greater than reducing FeO that from an economic standpoint FeO containing metallic iron is a much less costly method. However, I do not wish to limit myself to the production of this material from FeO alone, but wish to cover all forms of iron oxide. be they Fe203, Fes04, or FeO, for the production of this type of material.

By making use of copperas or ferrous sulphate I produce a purer, more ductile iron than can be commercially produced in any other way. 'I'he possibilities of this iron are not limited to the articles herein recited, nor to articles impregnated with oil and having frictional surfaces, or even to the formation of porous structures.

In making use of this material as a bearing, bushing, valve guide, piston, or the like, its low coeilicient of expansion is an important aspect. This low coeiicient of expansion with the lubri- Acation produced where the metal is impregnated with Oil, renders impossible the seizing or scoring of a shaft, even at extremely high temperatures. The metal itself, even when dried, has a low coefficient of friction. In the case of bearings or bushings, they are adapted not only for heavy loads at slow speeds but also at high speeds. The cost of the metal is low, and its weight is low, similar to aluminum, making it especially adapt able for pistons for internal combustion engines, Diesel engines, steam engines and other engines, and the light weight is obtained without a high coeiiicient of expansion, as is the case of aluminum pistons. I also contemplate the use of the metal for aeroplane parts and to replace aluminum wherever it is possible that weight and cost are a factor.

'Ihe ductility of this metal is shown as follows:

A "/8 inch round briquette 11/2 inches long, under a compressive load of 43,000 pounds per square inch, was reduced in length from 11A inches to 3A of an inch, showing no sign of rupture, and simply became a denser, more coherent mass.

Tensile strengths vary with the porosity. The tensile strength of the material may be increased by the addition of 5% copper to the briquet, and probably greater tensile strengths can be obtained by making use of other alloys.

In oiling, I frequently make use of an oil containing varying percentages of colloidal graphite which prepares and gives a quick bearing surface.

In making u'se of mill scale to produce a porous iron structure, the general run of mill scale has mechanically included in it a certain amount of siliceous material which contaminates. This may be removed from the mill scale by any of the well known gravity processes, such as tabling over a Wilfley table, or might, in some instances, be removed by magnetic concentration.

Mill scale consists essentially of Fe304, FeO, and a'small percentage of metallic iron. It is more or less diicult to reduce in that form, owing to its glaze or impervious nature; so, in making use of mill scale, after I remove the siliceous or foreign material from the oxide, I partially reduce the mill scale by making use of the same type of rotary kiln as I spoke of formerly in reducing FeiOa obtained from copperas. Only, in the case of mill scale, it is not necessary to calcine, as it contains no sulphur. I partially reduce the mill scale by making use of illuminating gas at a temperature of approximately 1700 F., thereby obtaining a product which is principally FeO and metallic iron. This product. when ground, can be briquetted and red to reduce the cxide to pure (or substantially pure) iron and of an open porous structure, in substantially the manner set out in connection with the FeO obtained from copperas,

An article formed in accordance with the present invention may be oiled from one side, for example, a side whichY is exposed, and the oil will seep or permeate through the intercommunicating pores to the other side, or sides, which may be concealed.

Where an article formed of the present material is impregnated with oil the oil will, upon heating of the article, expand so much faster than the metallic material that the article will sweat or exude oil when heated and take in or absorb the oil when cold.

I could grind and briquet the mill' scale without any previous treatment, but the time of reduction in a briquet form would be greater and more costly. However, mill scale as a source of raw material is one of the sources of raw material that the appended claims are intended to cover.

I claim:

1. The method of forming a substantially pure iron of open porous structure which comprises dividing an oxide of iron into relatively fine particles, adding a slight amount of carbon, mixing with a binder, packing the mixture into a briquetted shape by a series of percussive blows, and firing the shape in the presence of a reducing agent to reduce the oxide.

2. A process which comprises removing the siliceous or foreign material from mill scale, reducing the mill scale with the siliceous or foreign material removed to a product which is principally FeO and metallic iron, dividing the FeO and metallic iron into relatively line grains, mixing the same with a binder, packing the mixture into a briquetted mass by a series of percussive blows, and treating the mass to reduce the oxide of iron to substantially pure iron of an open porous structure.

3. The method of forming an integral body of substantially pure iron of intercommunicating porosity which comprises dividing FeO and metallics into relatively iine particles, packing the particles into a briquetted shape by a series of percussive blows and firing the same in the presence of a reducing agent to reduce the oxide into a porous integral body.

4. An integral ferrous body of porous structure, comprising a ductile mass of iron of spongy character produced by reducing to metallic form in situ a mass of iron oxide compacted by a series of percussive blows.

5. As a new material, an integral ductile spongy mass of iron having intercommunicating pores of minute size, the iron of the mass being formed in situ by reduction of an oxide compacted by a series of percussive blows, said mass having no tendency to disintegrate into powder under mechanical stress.

6. The process of forming an integral body of porous iron which comprises dividing iron oxide into relatively ne particles, mixing the same with nely divided carbon, packing the mixture into'a briquetted shape by a series of percussive blows, and firing the shape in the presence of a. reducing agent to reduce the oxide in situ into an integral substantially homogeneous mass of porous ductile iron.

7. The process of producing an integral ductile spongy mass of iron having intercommunicating pores of capillary size, which comprises mixing powdered iron oxide and a small amount of a heavy binder relatively high in carbon and of high viscosity to produce a mass which when compacted will hold its shape, disposing the mass in a mould, ramming the mass into the mould with high frequency percussive blows to cause compacting of the mass, then firing the mas in a reducing atmosphere to reduce the iron oxide in situ to metallic iron.

8. 'I'he method of forming an integral body of substantially pure iron of controlled porosity, which comprises mixing iron oxide and metallics both in relatively ne particles with powdered carbon, compacting the same into a definite a definite shape, removing the shape from the mould, and ring the shape in the presence of a reducing agent to produce in situ an integral mass of spongy iron.

10. The method of forming an integral bodyof substantially pure iron of intercommunicating porosity which comprises dividing an oxide of iron and metallics into relativelyV fine particles. packing the particles into a briquetted shape by a series of percussive blows, and firing the same in the presence of a reducing agent to reduce the oxide into a porous integral body.

1l. The method of forming an integral body of metal to produce a material having a bearing surface of relatively long life which comprises mixing relatively fine particles of iron oxide and carbon, subjecting the mix to a series of percussive blows to form a briquette, and firing the briquette at a temperature oi about 1700" F. in the presence of a reducing agent until it is reduced to substantially pure iron.

12. The method of forming an integral body of metal to produce a material having a bearing surface of relatively long life which comprises mixing relatively fine particles of iron oxide and carbon, subjecting the mix to a series of percussive blows to form a briquette, ring the briquette at a temperature of about 1700 F. in

`the presence of a reducing agent until it is reduced to substantially pure iron, and sintering the briquette at a temperature of about 2100 F. to produce a relatively porous structure having relatively great strength.

13. The method of forming an integral body of metal to produce a material having a'bearing surface of relatively long life which comprises mixing relatively fine particles of iron oxide and carbon, subjecting the mix to a series of percussive blows to form a briquette, firing the briquette at a temperature of about 1700 F. in the presence of a reducing agent until it is reduced to substantially pure iron, sintering the briquette at a temperature of about 2100 F. to produce a relatively porous structure having relatively great strength, and impregnating the sintered briquette with a lubricating medium to render it self lubrieating.

CHARLES FREDERIC SHERWOOD.

Images