US1756857A - Hard-metal composition and method of making the same - Google Patents

Description

A r-n 29, 1930.

E. G. GILSON HARD METAL COMFOSITION AND METHOD-0F MAKING THE SAME Original Filed April 28, 1927 lam/ant orn ey. v

Twp O.||..- 6% G A yQs r H e m Ev b Patented Apr. 29, 1930 E 'STATES PATENT OFFICE EMERY G. GILSON, 05E COLONTE, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COM- IANY, A CORPORATION OF NEW YORK HARD-METAL COMPOSITION AND METHOD -01E MAKING. THE SAME Application filed April 28, 1927, Serial No. 187,328. Renewed June 11, 1929,

The present invention relates to a hard metal composition and more particularly to a method of forming such a composition mto a hard, dense mass which is suitable forfluse as 5 a machine cutting tool, wire drawing die or the like.

Metallic compositions, consisting largely of a refractor metal of the sixth group of the periodic ta 1e, have heretofore been made by mixing, for example, as disclosed in the patent to Schroter No. 1,549,615, powdered tungsten carbide and a powdered auxiliary metal, such as cobalt, forming the powdered mixture in a mold under pressure, and then heating the molded bar to its sintering temperature. Metallic compositions formed in this manner may contain from about 5 to about 20 per cent of auxiliary metal, and the finished -product is suitable for use as dies, cutting tools, or the like depending on the amount of auxiliary metal employed. The above process, it will be noted, involves four separate and distinct steps, viz., forming tungsten carbide, mixing the latterwith an auxiliary metal, pressing the mixture, and sintering. The process of forming the carbide particularly involves difficulties since it necessitates the employment of high temperatures and requires three hours or more for its completion.

In the copen-ding application of Samuel L.

Hoyt, Serial No. 181,536, filed April 6, 192 7,

entitled Hard metal compositions and methods of making the same,-there is disclosed a further method for forming a hard, tough,

metallic structure, the latter method comprising mixing a carbide such as tungsten carbide with an auxiliary metal such as cobalt and simultaneously applying heat and pressure to the mixture.

It is one of the objects-of the present invention to provide a more simple and inexpensive process than that heretofore employed for making metal compositions of the above character. This object has been accomplishe'd by omitting the step in the former processes which involves the preformation of position into a hard, dense mass in a single operation.

In carrying out the invention a metal of the sixth group of the periodic table, preferably tungsten in powdered form, is mixed with powdered carbon and a powdered auxiliary or binder metal of the iron group, preferablv cobalt. The elements are thoroughly mixed and then subjected to pressure in a reducing atmosphere for a short time, approximately five minutes, at the sintering temperature of the mixture. The close contact of the characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, will best be understood from reference to the following specification taken in connection with the accompanying drawing in which the single figure shows diagrammatically a perspective viewpartly in section and partlyin elevation of a mold and assembled electrodes whereby my invention may be carried into effect;

The elements, preferably finely divided tungsten, carbon and cobalt, which comprises the finished product, are thoroughlymixed in any suitable manner and placed in a carbon mold 1 which may have a rectangular or other' suitable openin 2 extending therethrough. An electrode 3 ts slidably in the lower part of opening 2 and receives the powdered mixture thereon. A second electrode 4 is slidably mounted in the-upper art-of the opening. Current is supplied-to tlie electrodes 3 and 4 through metallic-connectors 5 and 6, while pressure is simultaneously ap lied through the electrodes to the powdere materials 7. A pressure of approximately 1,000 ounds per square inch is applied to the pow cred material at temperatures varying from 1300 to.

1450 C. depending on the mixture employed. The temperature employed will be the sintering temperature of the mixture and should be maintained from one to several minutes to obtain the best results.

The amounts of powdered or finely divided materials employed may be varied if desired. The carbon content, however, should not be less than three nor more than ten per cent of the tungsten content. A mixture containing an amount of carbon equalapproximately to 6 er cent of the tungsten content will be foun to give very satisfactory results. The amount of auxiliary metal contained in the mixture may be about per cent or more of the total content of the composition. Good cutting tools and dies have been obtained by employing either 5 per cent or per cent of auxiliary metal.

- While I have found that the elements, tungsten, cobalt and carbon, provide the most satisfactory composition for use as cutting tools and dies other elements of the sixth group of the periodic table may be substituted for the tungsten and likewise other metals of the iron group may be substituted for the cobalt if desired.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. The method of producing a metallic structure consisting largely of tungsten but containing appreciable amounts of carbon and an element of the iron group, which comprises mixing powdered tungsten, carbon and an element of the iron group, and applying pressure thereto at the sintering temperature of the mixture.

2. The method of making metallic structure suitable for use as a cutting tool, which comprises applying pressure to a finely divided mass of tungsten, carbon and cobalt at approximately the sintering temperature of the mass.

The method of making a cutting tool, which comprises mixing in finely divided form an element of the sixth group of the periodic table, an element of the iron group and carbon, and applying pressure thereto at the sintering temperature of the mixture.

4. A. metal cutting tool formed by the simultaneous applicat on of heat and pressure to powdered tungsten, carbon and cobalt.

5. The method of forming a metallic structure consisting largely of tungsten but containing appreciable amounts of carbon and cobalt, which comprises mixing powdered tungsten, carbon and cobalt in the desired proportions, heatingthe powdered materials to the sintering temperature of the mixture, and applying pressure thereto. I

6. The method of forming-a metallic structure consisting largely of tungsten but containing appreciable amounts of carbon and ,cobalt, which comprises mixing powdered tungsten, carbon and cobalt in the desired proportions, heating the powdered materials to the sintering temperature of the mixture, and simultaneously applying pressure thereto.

ture consisting largely of tungsten but containing from 5 to 25% cobalt and about 5.4% to 4.2% carbon, which comprises mixing powdered tungsten, carbon and cobalt in the above proportions, heating to the sintering temperature of the mixture and applying pressure thereto.

8. The method of forming a metallic structure consisting largely of tungsten but containing from 5 to 2.5% cobalt and about 5.4% to 4.2% carbon, which comprises mixing powdered tungsten, carbon and cobalt in the above proportions, heating to the sinteing temperature of the mixture and simultaneously applying pressure thereto.

9,. The method of forming a metallic struc ture consisting of tungsten carbide and an appreciable amount but not more than 25% of cobalt'which comprises mixing the elements, tungsten, carbon and cobalt in powdered form, heating them to the sintering temperature of the mixture and applying pressure thereto.

10. The method of forming a metallic structure consisting of tungsten carbide and an appreciable amount but not more than 25% of cobalt which comprises mixing the elements, tun sten, carbon and cobalt in powdered form, temperature of the mixture and simultaneously applying pressure thereto.

11. The method of making a hard strong metal composition consisting mainly of a metal of the 6th group of Mendelejefl"s eriodic table but containing apprecia lo amounts of carbon and metal of the iron group, which comprises mixing said metal'of the 6th group and said carbon, while uncombined with respect to one another, with said metal of the iron group, and consolidating said mixture into a hard strong body.

12. The method of making a hard strong metal composition consisting mainly of tungsten but containing appreciable amounts of carbon and cobalt, which comprises mixmg i'rce carbon with tungsten and cobalt, and consolidating the mixture into a hard strong body.

13. The method of making a hard strong metal composition consisting mainly of tungsten carbide but containing an apprec able amount of cobalt, which comprises providlug a. mixture containing free carbon, tungsten and cobalt, and consolidating the mixture into a hard strong body.

14. The method of making a hard strong metal composition consisting mainly of tungsten but containing appreciable amounts of carbon and cobalt, which comprises mixing the tungsten, carbon and cobalt each in 7 The method of forming a metallic struceating them to the sintering.

powdered form, and while uncombined with one another, and consolidating the mixture I into a hard strong body by theapplication of heat and pressure thereto.-

15. The method of-making a hard strong metal composition consisting substantially of tungsten, carbon and cobalt, the cobalt forming an appreciable amount but not more than 25% of the composition, which comprises mixing free carbon with tungsten and cobalt, and consolidatin the mixture into a hard strong body by t 1e application of heat and pressure thereto.

16. The method of making a carbide of an element of the 6th group of Mendelejefis periodic table, which comprises mixing free carbon with said element and metal of the iron group and heating the mixture to an elevated temperature.

17. The method of making tungsten carbide, which comprises providing a mixture containing tungsten, co alt and free carbon, and heating the mixture.

18. The method of acceleratin the formation of tungsten carbide, whic comprises heating a finely divided mixture consisting mainly of tungsten but containing appreciable amounts of cobalt and free carbon.

In witness whereof, I have hereunto set my hand this 27th day of lgpril, 1927.

vEMER e, GILSON.

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