US2113353A

US2113353A - Tungsten titanium carbide, wtic

Info

Publication number: US2113353A
Application number: US179551A
Authority: US
Inventors: Philip M Mckenna
Original assignee: Individual
Current assignee: Individual
Priority date: 1937-12-13
Filing date: 1937-12-13
Publication date: 1938-04-05
Anticipated expiration: 1955-04-05

Description

Patented v UNITED STATES PATENT OFFICE 2,113,353 TUNGSTEN TITANIUM CARBIDE, WTiOz Philip M. McKenna, Unity Township, Westmoreland County, Pa.

No Drawing. Application December 13, 1937,

Serial No. 179,551

7 Claims. (01. 23-44) This invention relates to carbides, and more the amount and proportions of the tungsten and particularly to a new composition of matter comtitanium content, the excess of tungsten or tiposed of tungsten, titanium and carbon, and cortanium remaining uncombined, so as to be readily responding to the chemical formula WTiCz. separable therefrom, along with the other result- The principal object of the invention is the proing substances.

duction of a carbide containing tungsten and The new carbide substance is prepared by heattitanium which will be extremely hard and 01' ing tungsten, or a substance containing tungsten great value and utility as a material for use, in such as tungsten oxide, or alloys of tungsten, accordance with the usual principles of powder with titanium, or a substance containing titani- 10 metallurgy, in the production of hard compoum, such as titanium oxide, in the presence of 10 sitions of matter, in order to effect great hardcarbon, in a menstruum metal, for which purpose ness combined with great strength, together with nickel has been found to be preferable, the suba low thermal conductivity and other characterstance being then separated by chemical and istics, which will enable the hard compositions of mechanical means from the resulting mass. I matter made from such carbide material to have have, likewise, prepared such carbide substance, 15

great utility and durability when used as the repeatedly, by employing as a menstruum metal cutting points in the cutting of metal at highcobalt, or a mixture of cobalt and nickel, and speeds, when used as dies, and when used to proit is probable that menstruum metals other than vide corrosion-resisting surfaces, and for other nickel and cobalt may be used. However, be-

similar uses. cause of the lowcost and the ease of its re- 20 A further object of the invention is the promoval, Iconsider the use of nickel to be preferduction of such a carbide, containing tungsten, able from a commercial 'standpointi 'The amount which, when used in the production of hard comof menstruum metal or metals, may vary widely, positions of matter, in accordance with the usual from an effective amount up to an amount conprinciples of powdermetallurgy, and with a siderably in excessof'the tungsten content, and 2 binder material containing powdered tungsten or I have found that the usef'of nickel or cobalt in molybdenum, or carburized tungsten or molybdean amount approximately equal-to the amount num, or other compounds of tungsten or molyb of tungsten gives the best results-froma comdenum, with or without nickel or cobalt, will yield mercial standpoint. If only a small amount of none of its carbon content to any of the metals mn truum al s 11S d.- t must" func i n y 30 so used as a binder in such hard compositions of solution of a little of the tungstenandftitanium matter. I at a time, such dissolved metals apparently com- A still further object of the invention is to bining in solution toform the carbide, thus freeprovide such a carbide which, when used as an ing the mens ruum m t l so h it i availa le ingredient in such a hard composition of matter, to dissolve a further quantity f the n n renders it possible to include in such hard-comand titanium. As will be apparent, the time position of matter a higher percentage of menecessary to complete thereaction under such tallic tungsten as a binder than has been praccircumstances is unduly prolonged. ticable heretofore, whereby the toughness and AS stat d ab ert e p s pp i a i n s d 40 breaking strength of such composition of matter rected t0 the new composition of matter which is 40 can be increased without a material decrease of produced by a process herein disclosed, butwhich the hardness and cutting ability of such compoprocess is described in detail, and claimed, in my sition of matter. copending application, Serial No. 179,552, filed of Further objects of the invention, together with even date herewith, to which reference is hereby -15 details of the steps by which the invention is put made. into practice, will be apparent from the follow- I have likewise invented certain new and useful ing specification. improvements in hard compositions of matter The new carbide substance which I have incontaining this new carbide substance as an invented, and obtained by the process herein degredient, described and claimed in my copending 5 scribed, is apparently a double carbide of tungapplication, Serial No. 179,553, filed of even date sten and titanium corresponding to the chemical herewith, and a process for making such hard formula WTiCz, and containing substantially compositions of matter, described and claimed in 71.9% W, 18.7% Ti, and 9.4% C, and it has been my copending application, Serial No. 179,554, also invariably obtained by following the process herefiled of even date herewith, to both of which apin described, regardless of wide variations in plications reference is hereby made.

In carrying out the process of forming this new carbide substance, the tungsten, titanium and menstruum metal ingredients, are heated, preferably in a graphite crucible, for a period of about five hours, at a temperature above 1600 C., and preferably approximately 2100 C. I have used slugs of tungsten metal, with bars of commercial nickel melting stock, with titanium oxide, and graphite chips, all placed together in a graphite crucible. I have also incorporated the tungsten in the form of WO: in such melts, with equally good results.

I have found it advisable to mix with the other materials chips or turnings of graphite, in an amount constituting about 5% of the tungsten and titanium materials combined. The mass resulting from the heating process, after cooling, is crushed, treated with water solutions of hydrochloric acid and a small amount of nitric acid, at boiling temperatures, or with similar oxidizing acid solutions such as hydrochloric acid to which potassium perchlorate has been added, treated with ammonia or other hydroxide solutions to remove W03, again treated with aqua regia, or other oxidizing acid solutions, to dissolve the Ni, and again treated with hydroxide solutions to dissolve any remaining W03. At various stages, during such treatments, the powdered material is subjected to mechanical concentration, as by panning or gravity concentration, as on a Wilfley table, to remove loose graphite and particles of light impurities. The particles remaining after such chemical and mechanical separation of other compounds, are grey particles having a metallic lustre. These particles are further treated, preferably in platinum dishes, with strong solutions of hydrofluoric acid, at a temperature up to its boiling point, to dissolve suboxides or blue oxides of tungsten, such as W02, and any other impurities. The hydrofluoric acid solution is removed by repeated washing and decantation, and the remaining particles are carefully panned or otherwise concentrated, as by gravity methods and dried, the remaining particles being grey in color, with high metallic lustre, having surfaces which are predominantly conchoidal and of a size averaging greater than .01 mm. in largest cross-section dimensions.

As a specific example of the process followed in the formation of such new carbide substance, and the characteristics, as shown by test, of the product obtained thereby, the following procedure was followed in one instance.

There was placed in a crucible, 6" in diameter, of substantially pure graphite:

Grams Tungsten rods 1840 Powdered TiO 800 Ni melting stock 2800 The graphite crucible, with such contentstherein, was placed in an electric induction furnace and heated, during a period of approximately an hour, to a temperature of 2100 C., and maintained at such temperature for a period of eight hours. After cooling, the product of such heating process was removed by breaking away the graphite crucible, and the mass was crushed by hammer and by a jaw crusher, together with coarse ball milling, until the particles thereof would pass a 40-mesh screen. The particles were repeatedly treated with water mixtures of hydrochloric acid to which a small amount of nitric acid had been added, the acid mixture being repeatedly boiled. After such acid treatments, the

particles were treated with ammonia solutions, to remove any W03, and were again treated with aqua regia, to dissolve nickel and nickel alloys and other impurities, and finally were again treated withammonia solutions. At various stages during such acid and hydroxide treatments, the particles were subjected 'to mechanical concentration by panning and were also concentrated by gravity methods on a Wilfley table to remove loose graphite and other light impurities, leaving only grey particles, obviously having a metallic lustre. The particles were further treated, in platinum dishes, with strong solutions of hydrofluoric acid, at a temperature up to the boiling point, to dissolve suboxides of tungsten such as W02. The hydrofluoric acid solution was removed by washing with water, and repeated decantation with fresh water and the particles were again carefully "panned and concentrated by gravity methods. From the above-mentioned mixture of materials, 1030 grams of such particles were obtained.

A carbon analysis was made of samples from such particles, and showed a carbon content of 9.40% C, which is quite close to the carbon content of 9.39% C, which theoretically should be present according to the formula WTiCz. This discrepancy of the carbon content found is within the error of analysis of the carbon content of materials of this type. A test of the tungsten and titanium content of such particles showed that they contained 71.86% W and 18.75% Ti, corresponding exactly with the content that theoretically would be present in WTiCz. Such particles were found to have a specific gravity of 9.72, which is much lower than would be indicated theoretically for a mixture of WC and TiC in the proportions of the metallic contents found by tests. Inasmuch as the specific gravity of WC is 15.64 and that of TiC is 5.0055, the calculated specific gravity, on the assumption that this product is a mixture of WC and TiC, would be 10.29. The melting point of the product was found to be higher than that of WC (2867i- 50 C.) and may be higher than that of TiC (3146: 50 C.). If the substance were a solid solution of TiC in WC, that is, a eutectic, one would expect the melting point to be lower than that of WC. Particles of the new carbide substance were treated with a standardized solution of hydrofluoric acid containing one drop of nitric acid and were found to dissolve in two hours, whereas an equivalent amount of a mixture of WC and TiC was dissolved in the same solution in less than two minutes.

In order to test further the new carbide substance WTlCz, as compared with a mixture of WC and TiC having the same ultimate metallic content, pairs of test pieces of hard compositions of matter were formed, as described in my copending application Serial No. 179,554, and using the same amount of the same binding materials, and following exactly the same process, except that one contained WTlCz and the other contained an equivalent amount of a mixture of WC and TiC. A number of such pairs of test pieces were made, using different binding materials, and with different proportions of carbide material and of binding material. In every case the hard compositions containing the new carbide substance WTiCz were found to exhibit a characteristically lower thermal conductivity than those made with mixtures of WC and TiC, showed greater strength and hardness, and likewise showed on repeated tests, in which such new hard anaasa compositions of matter were used as a me cutting tool point in machining steels and copper-silicon cast iron, much greater resistance to cratering and resistance to erosion and wear from chips oi both steel and cast iron, the compositions containing WTIC: lasting from four to five times as long as did the compofltions containing mixtures of WC and TIC, when used under identical conditions in the same machine, and cutting the same material at the same rate of speed.

The new carbide substance has been manufactured on a commercial basis in large quantities, and has been unvarylng in its physical characteristics and in its chemical analysis, being always produced in the expected quantity, as particles of a rather uniform size, with high metallic lustre, and with the surfaces of the particles predominantly conchoidal as seen under a highpower microscope.

I believe that the hard carbide substance, made by the process described, is a new chemical compound corresponding chemically to the formula WTiCz. My reasons for such belief are (1) the unvarying composition of the substance produced as described and always corresponding to the formula WTiC: by analysis, even when the quantities of the ingredients of the mixture initially heated are widely varied to include a large excess of W or of Ti; (2) its chemically difl'erent behavior when treated with aqua regia, as compared with WC and 110, as well as its chemically difl'erent behavior when treated with hydrofluoric acid containing a small amount of nitric acid; (3) its producing, when formed into a hard composition of matter in a binder of nickel or cobalt or other binder material, a composition which lasts from four to five times as long as a similar hard composition of matter made in identically the same way but with a mixture of WC and TIC, and having the same ultimate chemical analysis; (4) the characteristically lower thermal conductivity of hard compositions of matter containing it; (5) its lower density, as compared with that of a mixture of WC and TiC having the same vention is directed to such new composition of I matter either in its pure form, as produced by the process described, or with such incidental impurities.

What I claim is:

1. The new chemical compound corresponding I to the formula W'IiCz.

2. The new chemical compound consisting of tungsten, titanium and carbon combined in the proportion of one atom of tungsten, one atom of titanium and two atoms of carbon.

3. A carbide compound containing 71.86 per cent W, 18.75 per cent Ti and 9.39 per cent C.

4. A chemical compound containing approximately 71.9 per cent tungsten, approximately 18.7 per cent Ti, and approximately 9.4 per cent C., that is unattacked by aqua regia.

5. A chemical compound containing approximately 71.9 per cent W., approximately 18.7 per cent '11, and approximately 9.4 per cent C., in the form of particles averaging greater than .01 mm. in largest cross-section dimension and having a high metallic lustre.

6. A chemical compound containing approximately 71.9 per cent W., approximately 18.7 per cent Ti, and approximately 9.4 per cent C., and having a specific gravity of approximately 9.72.

7. A chemical compound containing approximately 71.9 per cent W., approximately 18.7 per cent Ti, and approximately 9.4 per cent 0., in the form of particles having surfaces predominantly conchoidal.

PHILIP M. McKENNA.