Preparation of alloys by the armstrong method

Abstract

A method and apparatus for making alloys or ceramics by the subsurface injection of an equilibrium vapor of a boiling liquid of the ceramic or alloys constituents is disclosed. Various powders and products are disclosed.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 11/372,660, filed Mar. 10, 2006; which is a divisional of U.S. Ser. No. 10/654,493, filed Sep. 3, 2003, now U.S. Pat. No. 7,041,150; which application pursuant to 37 C.F.R. 1.78(c), claims priority based on provisional application U.S. Ser. No. 60/408,934, filed Sep. 7, 2002; the entire disclosures of each of these applications are hereby expressly incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to the Armstrong process as described in U.S. Pat. Nos. 5,779,761, 5,958,106 and 6,409,797, the disclosures of each of which is incorporated herein by reference. As disclosed in the above-three patents, alloys or ceramics can be prepared by establishing a mixture of gases which are fed, as disclosed in the above referenced patents, subsurface to a reducing metal thereby to initiate the reduction of the gas mixture to the corresponding alloy or ceramic. In general, the most obvious way to provide the mixed vapor is to introduce the constituent vapors in the required atomic ratio to a manifold and feed the mixed material to the reducing metal.

The present invention relates to another means for mixing the alloy or ceramic constituents prior to the introduction of the mixed vapor to the reducing metal. In the present invention, the various constituents of the alloy or ceramic are initially mixed as a liquid which is thereafter boiled. After the liquid is boiled and reaches equilibrium, the vapor coming off the liquid has the same atomic ratio as the feed liquid to the boiler, which may or may not be different than the liquid in the boiler. At steady state, the vapor from the boiler can be fed to the Armstrong process in the same manner as illustrated in the three referenced patents to produce an alloy or ceramic having a constant atomic ratio.

This invention simplifies the handling of materials, particularly those materials such as aluminum chloride which sublimate rather than boil. For those materials, the solid is heated in a vessel under pressure so that a liquid is formed and that liquid is thereafter transmitted to a boiler, as will be shown. By way of example, a boiler having feed streams of aluminum chloride and vanadium chloride and titanium chloride in atomic ratios of 6% Al and 4% V and the remainder Ti will produce at equilibrium a vapor of 6% Al, 4% V and 90% Ti, even if the atomic ratios of the constituents of the liquid in the boiler differ. Using the equilibrium vapor as a feed in the process disclosed in the referenced patents produces a 6% Al, 4% V, titanium alloy.

The invention applies to a wide variety of alloys or ceramics and simplifies the materials handling of the constituent parts of each alloy produced in the Armstrong Process.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a method and apparatus of producing an alloy or ceramic in which the liquid constituents thereof are fed into a boiler. The equilibrium vapor therefrom is thereafter used in the subsurface reduction with a liquid alkali or alkaline earth metal to form the alloy or ceramic.

Yet another object of the present invention is to provide a method of producing an alloy or ceramic by the exothermic subsurface reduction of a mixed halide vapor of the alloy or ceramic constituents with liquid alkali or alkaline earth metal or mixtures thereof, comprising providing a liquid mixture of halides of the alloy or ceramic constituents in a preselected atomic ratio, boiling the liquid until an equilibrium with the vapor is attained, and thereafter introducing the equilibrium vapor into the liquid reductant metal to form an alloy or ceramic powder of the equilibrium vapor constituents in the preselected atomic ratio.

Still a further object of the present invention is to provide a method of producing an alloy by the exothermic subsurface reduction of a mixed halide vapor of the alloy constituents with liquid alkali or alkaline earth metal or mixtures thereof, comprising providing a liquid mixture of halides of the alloy constituents in a preselected atomic ratio, boiling the liquid until an equilibrium with the vapor is attained, and thereafter injecting the equilibrium vapor into the liquid reductant metal at greater than sonic velocity to form an alloy powder of the equilibrium vapor constituents in the preselected atomic ratio.

Another object of the present invention is to provide an apparatus for practicing the method hereinbefore discussed.

The invention consists of certain novel features and a combination of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the details may be made without departing from the spirit, or sacrificing any of the advantages of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of facilitating an understanding of the invention, illustrated in the accompanying drawings is a preferred embodiment thereof, from an inspection of which, when considered in connection with the following description, the invention, its construction and operation, and many of its advantages should be readily understood and appreciated.

FIG. 1 is a schematic representation of the apparatus and system for practicing the method of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a system 10 having a reactor 15 in communication with a source 20 of liquid reductant metal connected to the reactor by a pipe 21.

A boiler 25 has therein a liquid 26 which when boiled produces at equilibrium a vapor 27 which is introduced via pipe 30 into the pipe 21 preferably but not necessarily carrying a flowing stream the liquid metal from the source thereof 20, thereby producing a slurry 40 of the same type, consisting of excess liquid metal, ceramic or metal powder and a salt produced during the reaction as discussed in the above referenced Armstrong et al. patents.

The boiler 25 is provided with a heat source such as coils 28 and is connected or in communication with a plurality of sources of the constituents of the ultimately produced alloy or ceramic, three such sources 35, 36, and 37 being illustrated.

The advantage of the present invention is that during the production of a ceramic or an alloy by the Armstrong method, liquid handling is frequently easier and more efficacious than handling vapors. To this end, representative constituent sources 35, 36 and 37 can each be a vessel (pressurized or not) in which the individual constituent halide is maintained as a liquid and thereafter transferred in a suitable, predetermined, atomic ratio into the boiler 25. The atomic ratio of the constituents from each of the sources 35, 36 and 37 determines the atomic ratio of the constituents in the vapor 27 at equilibrium with the liquid 26. Thereafter, the equilibrium vapor 27 in the preselected and predetermined atomic ratios is injected subsurface into a stream of liquid metal at greater than sonic velocity, as is taught in the above-referenced Armstrong patents.

Although the reductant metal may be any suitable alkali or alkaline earth metal or mixtures thereof, the preferred reductant metal is sodium or magnesium, the most preferred reductant metal being sodium. Although a variety of halides may be used, the preferred halide is a chloride due to availability and cost. Although frequently described with respect to titanium, the invention is in fact applicable to a wide variety of alloys and ceramics, particularly ceramics including a nitride, a carbide, or a boride or mixtures thereof. In addition, many alloys may be produced by the method and apparatus of the subject invention, particularly those alloys or ceramics that include one or more of Ti, Al, Sb, Be, B, Ta, Zr, V, Nb, Mo, Ga, U, Re, or Si. More preferably, alloys or ceramics are produced which include one or more of Ti, Al, Ta, Zr, V, Nb, Mo, Ga, Re, or Si.

Moreover, the powder ceramics or alloys produced by the method and apparatus of the present invention are useful in a wide variety of processes to make many different products. For instance, various powder metallurgy techniques may be used to produce product from the powder made by the method and apparatus of the present invention. Moreover, a wide variety of alloy and ceramic powders may be either melted or compressed to form a solid from the powder of the present invention. A particularly important alloy at the present time is the 6:4 alloy of titanium. This alloy is widely used in aerospace and defense and is substantially 6% aluminum and 4% vanadium with the remainder being substantially titanium.

As taught in the cited Armstrong et al. patents, the reductant metal is generally present in excess of the stoichiometric amount needed to reduce the mixed halide vapor injected subsurface of the reductant metal. More particularly, when the reductant metal is present in the range of from about 20 to about 50 times the stoichiometric amount, which enables the entire steady state reaction to be maintained at or around 400° C., an advantageous and mostly preferred temperature occurs. The exact temperature at which the steady state reaction is maintained depends, in part, upon the ratio of halide to reductant metal, as well as the individual vapors being reduced and the reductant metals used to reduce same. It is within the skill of the art to calculate the exact ratios required to provide a predetermined steady state operating temperature for the process producing any of the wide variety of ceramics or alloys made by the method and apparatus of the present invention.

As previously stated, although the examples herein are discussed with respect to titanium or titanium alloys, a wide variety of alloys and ceramics may be made by the present invention. It is intended to cover in the claims appended hereto, all such alloy and ceramics particularly, but not exclusively, the nitride, boride or carbide ceramics. Representative alloys of the present invention are those which include one or more of Ti, Al, Sb, Be, B, Ta, Zr, V, Nb, Mo, Ga, U, Re, or Si and, most preferably, one or more of Ti, Al, Ta, Zr, V, Nb, Mo, Ga, Re, or Si.

While there has been disclosed what is considered to be the preferred embodiment of the present invention, it is understood that various changes in the details may be made without departing from the spirit, or sacrificing any of the advantages of the present invention.

Claims

1. A powder made by the exothermic subsurface reduction of a mixed halide vapor comprising principally a titanium halide and an amount of a halide of at least one other element in a preselected atomic ratio with a liquid reductant metal comprising liquid alkali or alkaline earth metal or mixtures thereof, wherein the mixed halide vapor is generated by boiling a liquid mixture of halides until an equilibrium vapor is attained, and thereafter introducing the equilibrium vapor into the liquid reductant metal to form the powder comprising principally titanium and an amount of the at least one other element in the preselected atomic ratio.

2. The powder of claim 1, wherein the at least one other element is B.

3. The powder of claim 2, wherein the powder is a titanium alloy powder and the at least one other element further includes one or more elements selected from the group consisting of Al, Sb, Be, Ta, Zr, V, Nb, Mo, Ga, U, Re and Si.

4. The powder of claim 3, wherein the titanium alloy powder includes Al and V.

5. The powder of claim 4, wherein the alloy powder is substantially 6% Al and 4% V with the remainder substantially Ti.

6. The powder of claim 1, wherein the liquid reductant metal is Na or Mg.

7. The powder of claim 1, wherein the halide is a chloride.

8. The powder of claim 1, wherein the liquid reductant metal is present in excess of the stoichiometric amount.

9. The powder of claim 8, wherein the liquid reductant metal is present as a flowing stream.

10. The powder of claim 1; wherein the equilibrium vapor is introduced into the liquid reductant metal by subsurface injection at greater than sonic velocity.

11. A solid produced from the powder of claim 1.

12. An apparatus for producing a powder by the exothermic subsurface reduction of a mixed halide vapor comprising principally a titanium halide and an amount of a halide of at least one other element in a preselected atomic ratio with a liquid reductant metal comprising liquid alkali metal or alkaline earth metal or mixtures thereof, the apparatus comprising:

a storage container for storing the liquid reductant metal,

halide containers for storing each of the titanium halide and the halide of the at least one other element in liquid form,

a boiler in communication with each of the halide containers, wherein the titanium halide and the halide of the at least one other element are transferred in a preselected atomic ratio to the boiler to form a liquid mixture of halides,

heating mechanism in heat exchange relationship with the boiler to generate an equilibrium vapor from the liquid mixture of halides,

a reactor in communication with the boiler and the storage container for the liquid reductant metal, wherein the liquid reductant metal is transferred from the storage container to the reactor, and

injection mechanism for subsurface injecting the equilibrium vapor from the boiler into the liquid reductant metal in the reactor to produce the powder in the preselected atomic ratios.

13. The apparatus of claim 12, wherein the at least one other element is B.

14. The apparatus of claim 13, wherein the powder is a titanium alloy powder and the at least one other element further includes one or more elements selected from the group consisting of Al, Sb, Be, Ta, Zr, V, Nb, Mo, Ga, U, Re and Si.

15. The apparatus of claim 14, wherein the titanium alloy powder includes Al and V.

16. The apparatus of claim 15, wherein the alloy powder is substantially 6% Al and 4% V with the remainder substantially Ti.

17. The apparatus of claim 12, wherein the liquid reductant metal is Na or Mg.

18. The apparatus of claim 12, wherein the halide is a chloride.

19. The apparatus of claim 12, wherein the liquid reductant metal in the reactor is present in excess of the stoichiometric amount.

20. The apparatus of claim 19, wherein the liquid reductant metal in the reactor is present as a flowing stream.

21. The apparatus of claim 12, wherein the equilibrium vapor is injected into the liquid reductant metal at greater than sonic velocity.