Method of Manufacturing Pure Titanium Hydride Powder and Alloyed Titanium Hydride Powders By Combined Hydrogen-Magnesium Reduction of Metal Halides

• US 20130315773A1
• Filed: 05/24/2012
• Published: 11/28/2013
• Est. Priority Date: 05/24/2012
• Status: Active Grant

• Current Assignee: Advance Materials Products, Inc.
• Original Assignee: Advance Materials Products, Inc.
• Inventors: Moxson, Vladimir S., Duz, Volodymyr A., Klevtsov, Andrey G., Sukhoplyuyev, Viktor D., Sopka, Mihajlo D., Shuvalov, Yury V., Matviychuk, Mykhailo
• Granted Patent: US 9,067,264 B2
• Time in Patent Office: Days
• US Class Current: 419/28
• CPC Class Codes: B22F 2003/248 Thermal after-treatment
• CPC Class Codes: B22F 2201/013 Hydrogen
• CPC Class Codes: B22F 2998/10 Processes characterised by the sequence of their steps
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/02 Compacting only
• CPC Class Codes: B22F 3/1007 Atmosphere B22F3/1021 takes precedence
• CPC Class Codes: B22F 3/1017 Multiple heating or additional steps B22F3/101 takes precedence
• CPC Class Codes: B22F 3/11 Making porous workpieces or articles
• CPC Class Codes: B22F 3/24 After-treatment of workpieces or articles B22F3/1146 takes precedence
• CPC Class Codes: B22F 9/04 starting from solid material, e.g. by crushing, grinding or milling C22C1/1084 takes precedence; crushing, grinding or milling, in general, see the relevant subclasses, e.g. B02C
• CPC Class Codes: B22F 9/18 with reduction of metal compounds
• CPC Class Codes: B22F 9/20 starting from solid metal compounds
• CPC Class Codes: C01B 6/02 Hydrides of transition elements; Addition complexes thereof
• CPC Class Codes: C01B 6/24 Hydrides containing at least two metals; Addition complexes thereof C01B6/13 - C01B6/23 take precedence

Abstract

The invention relates to energy-saving manufacturing of purified hydrogenated titanium powders or alloying titanium hydride powders, by metallo-thermic reduction of titanium chlorides, including their hydrogenation, vacuum separation of titanium hydride sponge block from magnesium and magnesium chlorides, followed by crushing, grinding, and sintering of said block without need for hydrometallurgical treatment of the produced powders.

Methods disclosed contain embodiments of processes for manufacturing high-purity powders and their use in manufacturing near-net shape titanium and titanium-alloy articles by sintering titanium hydride and alloyed titanium hydride powders produced from combined hydrogen-magnesium reduction of titanium chlorides, halides and hydrides of other metals. Additional titanium hydride powder introduced with titanium tetrachloride beneficially affects the kinetics of magnesium-thermic reduction due to formation of the additionally-emitted atomic hydrogen, which helps to reduce presence of oxides and so cleans inter-particle interfaces of the product and enhances diffusion between all of components of the powder mixture.

Claims

1. A method of manufacturing pure and alloyed titanium hydride powders by the combined hydrogen-magnesium reduction of metal halides, comprising of the following reaction-related and operational steps:

(a) filling a reaction retort with liquid metallic magnesium and supplying hydrogen into the retort at 750-850°

C. followed by the dissolution of hydrogen into liquid magnesium up to saturation,

(b) supplying liquid titanium tetrachloride TiCl₄ into the retort filled with liquid magnesium to provide for the reduction of titanium from the titanium tetrachloride and the formation of magnesium chloride as a byproduct of this reaction,

(c) introducing at least one component from a group consisting of titanium hydride powder, gaseous hydrogen, and metal halides, together with liquid titanium tetrachloride TiCl₄, in the form of a pulp into the retort, whereby the amount of the titanium hydride powder is in the range of 0.1-10 wt. % of the titanium product to be produced from the titanium tetrachloride for the whole processing cycle,

(d) dissociation of the titanium hydride into titanium and hydrogen at 750-850°

C., followed by the formation of hydrogen gas micro-bubbles, which bubble in both the liquid phases of magnesium and magnesium chloride, increasing the rate of the reduction process by increasing the effective surface of reacting phases, destroying a magnesium chloride film on the surface of the molten magnesium, and generating a turbulent gas phase above the liquid in the retort,

(e) dissolution of hydrogen into the reduced titanium metal to the end of reduction reaction at 750-850°

C., in the amount of 30-180 cm³ of hydrogen per 1 g of titanium and the formation of a sponge-like titanium hydride, having a composition of TiH_x, where x is in the range of 0.3-1,

(f) vacuum separation of the titanium hydride sponge block at 1000-1050°

C., accompanied by the homogenization of alloyed titanium hydride and by the additional emission of hydrogen from the titanium hydride, destruction of the sponge'"'"'s closed pores due to the density differences of the titanium hydrides because of their varying hydrogen content, resulting in effective liberation and removal of residual magnesium and magnesium chloride,

(g) supplying additional cold hydrogen into the retort after the removal of a part of magnesium and magnesium chloride, decreasing the temperature in the center of the retort down to 600-640°

C., which is accompanied by polymorphic transformation, the additional hydrogenation of the titanium sponge, and by cooling the retort from the outside, whereby the cooling rate is decreased due to high thermal conductivity of hydrogen,

(h) at least partial crystallization of the metallic magnesium and magnesium chloride that results in additional stresses to the in titanium hydride sponge block, resulting in at least a partial disintegration of the sponge, providing evaporation and the easy removal of magnesium and magnesium chloride during the subsequent step of vacuum separation,

(i) raising the temperature of the metal hydride sponge block in the center of retort to 1000-1050°

C., due to the high thermal conductivity of the supplied hydrogen, cutting the total time of separation upon the heat transfer,

(j) de-hydrogenating the sponge block in vacuum at 1000-1050°

C. followed by hydrogenation at temperatures in the range of 600-640°

C., and promoting a destruction of the sponge block'"'"'s pores due to changes in the lattice structures and bulk densities of the newly formed compositions due to phase transformation at different temperatures, all resulting in a reduced total time of separation,

(k) the final removal removing of the magnesium chloride MgCl₂ and the metallic magnesium from the sponge block by vacuum separation,

(l) cooling of the sponge block to room temperature in the hydrogen atmosphere by permanently purging hydrogen through the retort to increase the brittleness of the titanium hydride sponge, and further, saving the energy needed for the disintegration of the sponge in the retort, and

(m) the mechanical disintegration of the titanium hydride sponge block inside the retort, as well as the alloyed titanium hydride sponge block, after hydrogenation in the process of cooling in the hydrogen atmosphere according to step (l), whereby the disintegration is carried out in one of the following atmospheres;

hydrogen, inert gas, and vacuum.

2. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 1, wherein metal halides, represented according to the general formula MeHl_x (where Me is a metal such as Ti, V, Al, Mo, Cr, Nb, Zr, Fe, Pd, Ru, Ni, W, Ta, Sn, Co, and Hl is chloride, fluoride, bromide, iodide), are introduced into the retort simultaneously with the titanium hydride powder.

3. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 2, wherein metal halides in the solid, liquid, and gaseous form are supplied simultaneously into the retort to the surface of the liquid magnesium, starting the first step of the reaction of titanium reduction.

4. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 1, wherein metal hydrides such as vanadium hydride, chromium hydride, zirconium hydride, molybdenum hydride, and other metal hydrides, are introduced into the retort simultaneously with the titanium hydride powder.

5. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 1, wherein gaseous hydrogen is introduced into the retort simultaneously with the titanium hydride powder, metal halides, individual metal powders, and master alloy powders.

6. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 1, wherein gaseous hydrogen is introduced into the retort before the introduction of the titanium hydride powder, metal halides, individual metal powders, and master alloy powders.

7. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 1, wherein gaseous hydrogen is introduced into the retort after the introduction of the titanium hydride powder, metal halides, individual metal powders, and master alloy powders.

8. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 1, wherein the alloying components are added into the retort in the form selected from a group consisting of solid powder of individual metals, master alloys, metal hydrides, metal halides, and combinations thereof.

9. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 1, wherein the inner surface of the retort is covered by metal sheets or foils, where the metal is selected from a group consisting of niobium, molybdenum, tantalum, and alloys thereof, which maintains temperature of the reduction and separation processes, and prevents the contamination of the resulting titanium hydride powder by iron, nickel, and chromium of the retort material.

10. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 1, wherein the resulting titanium hydride powder is ground inside the retort to the required particle size, using mechanical crushing, and is replaced from the retort by pneumatic transport using argon followed by packing the powder into drums without any contact with air.

11. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 1, wherein the cold compaction of the titanium hydride powder is carried out under argon to manufacture oxygen-free green articles before sintering.

12. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 1, wherein cold compaction of the mixture of titanium hydride powder with other metal hydrides, which were produced together with the said titanium hydride in the same retort, is carried out under argon to manufacture oxygen-free green titanium alloy articles before sintering.

13. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claims 1-12, wherein the compacted pure titanium hydride or alloyed titanium hydride green articles are placed under argon protection into a capsule that is filled with hydrogen, argon, or is outgassed to vacuum, and is placed into a furnace, where the green articles are sintered at 1200-1300°

C.

14. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claims 1-12, wherein the sintered titanium or titanium alloy articles are cooled to room temperature and subjected to high temperature deformation by forging, rolling, extrusion, flow forming, and other high temperature processing.

15. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claims 1-12, wherein the sintered titanium or titanium alloy articles are cooled to temperatures in the range of 750-1150°

C. and are subjected to multi-runs hot rolling, forging, or pressing.

16. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 1-12, wherein the sintered titanium or titanium alloy articles are subjected to multi-runs hot rolling, forging, or pressing immediately after sintering, without cooling.

17. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claims 1-12, wherein the sintered titanium or titanium alloy articles are cooled to room temperature and subjected to deformation by forging, rolling, extrusion, flow forming, and any other room temperature processing.

18. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 1-12, wherein the sintered titanium or titanium alloy articles are subjected to multi-runs hot rolling, forging, or pressing immediately after sintering, without cooling.

19. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 1, wherein solid metallic magnesium is filled into and melted in the reaction retort hydrogen is supplied into the retort at 750-850°

C., followed by the dissolution of hydrogen into the liquid magnesium up to saturation.

20. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 1, wherein the compacted titanium hydride or alloyed titanium hydride green articles are sintered in three steps:

heating to the initial dehydrogenation temperature of up to 350-450°

C., using special furnace fixtures to remove the emitted hydrogen,

heating to temperatures where the complete removal of hydrogen takes place at 650-750°

C., holding at this temperature for the time equal to the thickness of the cross-section in inches multiplied by 30 minutes, and

subsequent sintering at 1200-1300°

C.

21. The method of manufacturing pure and alloyed titanium hydride powders by the combined hydrogen-magnesium reduction of metal halides according to claim 1, wherein chemical reactions, hydrogenation, or dehydrogenation of the pure or alloyed titanium hydride powders is carried out at temperatures 50-250°

C. below that of equilibrium, to slow down the diffusion exchange of the retort material and the titanium hydride powders and to diminish their contamination.

22. The method of manufacturing pure and alloyed titanium hydride powders by the combined hydrogen-magnesium reduction of metal halides according to claim 1, wherein the powder of titanium dioxide TiO₂ is introduced into the retort in additional amounts, ranging from 0.01 wt. % to 10 wt. % based on the total weight of the retort charge, in order to control the content of oxygen dissolved into the titanium hydride particles, whereby in doing so, an oxide layer on the surface of titanium hydride particles is removed by the atomic hydrogen that is emitted during the dehydration of the said titanium hydride.

23. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 1, wherein the manufacturing process is continuous and comprises the following steps:

(a) liquid magnesium is supplied in an inclined tube, it fills the tube profile partially and glides upon gravitation and rotation of the tube,

(b) titanium tetrachloride, titanium hydride powder, master alloys, and hydrogen are supplied in the space between liquid magnesium and the wall of tube, whereby the mixture (the pulp) of all components takes the whole volume of the tube,

(c) said pulp is supplied in a tall intermediate retort, which is permanently outgassed by vacuum pumps,

(d) magnesium and magnesium chloride are vaporized and condensed (accumulated) in the outside condenser,

(e) hydrogen is supplied in this intermediate retort through a screw-equipped pipe,

(f) solid titanium hydride is formed in the bottom zone of the retort, where magnesium and magnesium chloride are fully evacuated,

(g) titanium hydride mass is permanently mixed by a screw tooling that is available at the bottom of the retort, in order to avoid sintering of titanium hydride at the process temperature 900-950°

C.,

(h) titanium hydride is saturated by countercurrent flow of cold hydrogen gas that is supplied in the screw-equipped outlet pipe, which transports titanium hydride out of the retort. The consumption of hydrogen is adjusted to the amount that provides its temperature of 600-650°

C. at the entrance of the retort from the outlet pipe, and also, the hydrogen temperature should be below the temperature of boiling of magnesium chloride at current grade of vacuum,

(i) produced titanium hydride is finally cooled by cold hydrogen at the exit of the outlet pipe to the temperature 120-150°

C., which is safe in terms of oxidation or ignition, and

(j) cold titanium hydride powder is supplied in metal drums without a contact with air, whereby argon expels hydrogen from the packed powder.

24. The method of manufacturing pure and alloyed titanium hydride powders by combined hydrogen-magnesium reduction of metal halides according to claim 1, wherein the manufacturing process is semi-continuous and the lid-free retort is moved sequentially along several stands, whereby each stand is designated for a single technological operation:

(a) transportation of a car with the retort from one stand to another is carried out in a pusher-type furnace filled with argon under pressure,

(b) stands are separated one from another by an insulating partition,

(c) at the first stand, the retort is dried and inspected,

(d) at the second stand, the retort is filled with liquid magnesium,

(e) at the third stand, the retort is filled with hydrogen that is dissolved in magnesium,

(f) at the forth stand, liquid titanium tetrachloride is supplied into the retort together with halogens of alloying metals, master alloy powders, individual metal powders and other components,

(g) at the fifth, the first vacuum separation is carried out,

(h) at the sixth stand, the first hydrogenation of titanium is carried out,

(i) at the seventh stand, the second (final) vacuum separation is carried out,

(j) at the eighth stand, the final hydrogenation of titanium is carried out,

(k) at the ninth stand, the resulting titanium hydride product is disintegrated in the retort, and pneumatically removed from the retort, and

(l) at the tenth stand, the retort is cleaned from the process residues.