JPS5888102A - Method of hydrogenating body-centered cubic phase alloy at room temperature - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the reaction of hydrogen gas with transition metal alloys, particularly the rapid reaction of hydrogen gas with alloys containing niobium or tantalum at mild temperatures.

Most of the metals that form hydrides are bulky and react very slowly with hydrogen gas at room temperature.

For example, the metal niobium is bulky and relatively inert at room temperature in the presence of hydrogen gas, and hydrogen dissolves very slowly into the raw stone cubic phase structure of the metal until it becomes saturated.
phase formation), then the added hydrogen reacts only slowly to form a niobium hydride phase. Other metals that form hydrides react in a largely similar manner. The rates of alpha phase formation and hydride formation vary between metals and alloys, but
It rarely occurs within 1 hour at room temperature. Attempts to increase this speed by nickel or radium or iron plating on niobium have been reported.

For many metal hydride applications, the hydride is formed from bulk metal, the hydride is pulverized into some form with a granule or powder structure, and then the hydrogen atoms are cyclically removed. It is desirable to form a lower hydride or a free metal, and then reintroduce hydrogen atoms to form the original hydride. When starting from a bulk metal or a bulk alloy, the metal may be
It is usual to react with hydrogen under high pressure after an induction period of heating to a temperature between 000 and 700°C, and then to cool the system very slowly to a temperature below about 100°C (preferably about room temperature). is necessary. At higher temperatures the rate at which hydrogen dissolves in the metal (alpha phase) increases and saturation is achieved on the order of minutes rather than hours or days.

However, at high temperatures, the equilibrium pressure of hydrogen is high, so relatively small amounts of hydrogen actually dissolve or form hydrides.

Therefore, after the formation of the saturated alpha phase, hydrides are formed only upon gradual cooling. Many metals require only one induction step to form a hydride, after which the hydride powder is circulated at a reasonable rate; It is important to clarify the points that are clearly disadvantageous.

Surprisingly, certain alloys of molybdenum, niobium, and tantalum, even in bulk, react rapidly with hydrogen at moderate temperatures (e.g., below about 100°C) to form hydrides in seconds or minutes even at room temperature. It was found that Accordingly, the present invention provides hydrogen gas at a temperature of about 0 to about 100° C. to (α) a first metal forming a body-centered cubic phase structure selected from the group consisting of niobium, tantalum, and mixtures thereof;
and (b) at least one selected from the group consisting of aluminum, cobalt, chromium, iron, manganese, molybdenum, nickel, copper, vanadium, silicon, germanium, gallium and mixtures thereof dissolved in these body-centered cubic phase structures. reacting with a solid solution comprising at least about 0.5 atomic percent of about one second metal, such that the reaction rate of the solid solution with hydrogen at the above temperature is greater than the reaction rate of the first metal with hydrogen at the above temperature and equal hydrogen pressure; A method for producing a metal hydride, the reaction rate being at least about twice that of the reaction rate of

According to the invention, hydrogen is reacted with a solid solution of at least two metals at low temperatures. The hydrogen gas used may be pure hydrogen at the dissociation pressure of the hydride formed at the reaction temperature, such as reduced pressure, atmospheric pressure or overpressure (eg 0.1 to about 10,000 &Pα). This pressure may also be taken as the partial pressure of hydrogen in a mixture with other gases that do not harm the hydride formation reaction. hydrogen as an inert gas,
For example, it may be mixed with argon, helium and nitrogen.

Additionally, hydrogen may be present in mixtures with gases that are deleterious to most hydride-forming reactions, but to which the particular solid solutions of the present invention are insensitive, such as carbon oxides, water vapor, and oxygen. Good too. The invention is therefore useful for removing hydrogen from gaseous mixtures of this type, for example from mixtures of hydrogen and helium produced during industrial hydrogen-forming reactions, or from mixtures of hydrogen and carbon monoxide or carbon dioxide. It can be used as a means to remove hydrogen from. The reaction temperature is preferably about 0 to about 100°C at the beginning of the reaction.

Since many reactions within the scope of this invention are highly exothermic, it is expected that temperatures will exceed 100° C. for short periods without adverse effects on the reaction.

In fact, heat removal acts as the rate-limiting step in many of the reactions of the present invention, with reactions taking place within seconds if adequate heat removal is provided. It is preferred to initiate the reaction below about 50°C, with room temperature being convenient for initiation.

The solid solution alloy used in the present invention contains niobium, tantalum, or a mixture thereof as the first metal. Since these two metals are completely soluble in each other and both form a body-centered cubic phase structure, they can be used in any ratio with respect to each other. Niobium is preferred because it is easier to obtain and cheaper.

The second metal is a transition metal of the group cobalt, chromium, iron, manganese, nickel, copper, vanadium or mixtures thereof, or a group selected from aluminum, silicon, germanium, gallium or mixtures thereof. It may be an element of the group. Preferably, at least about 0.5 atomic percent of the second metal is used, with the upper limit of the second metal being determined by the limits of solubility of the second metal in the body-centered cubic phase structure formed by the first metal. generally determined.

For metals with adequate solubility, a range of about 1 to about 10% of the second metal is preferred. When using mixtures of second metals, it is sometimes possible to exceed the proportion of second metal that is acceptable for a particular second metal alone. For certain metals, such as vanadium, the preferred maximum content of the second metal is about 60 M% of the total mixture, provided that solubility is sufficient.
It is.

Particularly preferred are compositions of vanadium and niobium with about 40 to about 60 atomic percent of each metal.

Table 1 below shows Max Noh Nsen's ``Binary Alloy 1''.
The effective metal radii of each of the first metal and second alloy used in the present invention are shown based on the values reported in Table B' of ``Structures of 265'' (Matsufugrow-Hill, 1958). The value for 0N=12 is changed to ON=8 by dividing by 1.03. Generally suitable second metals are transition metals having a metal radius at least about 5% smaller than that of niobium (and smaller than the same radius of tantalum). At least about 5% smaller than the atomic radius of niobium
Other second transition metals with small atomic radii are such that they contain at least about 0% in the body-centered cubic phase formed by niobium.
．． It would be suitable if it could dissolve about 5 at.%.

For non-transition metals (eg, aluminum, gallium, germanium, and silicon), a metal radius that is at least about 5% smaller than the metal radius of Nio/ is not required. The behavior of the second metal in hydride formation is not a determining factor in the rapid reaction rate of the present invention; some suitable second metals have low equilibrium hydrogen pressures for binary hydrides, and others The equilibrium hydrogen pressure is extremely high. As shown in Comparative Example 2, certain transition metals such as titanium or zirconium listed at the end of Table 1, which have a larger metal radius than vanadium, are not suitable and the reaction howler obtained when alloyed with niobium. is low.

However, the solid solution of the present invention is not intended to exclude secondary metals other than the first and second metals at the front station. For example, zirconium is not a suitable second metal, although it may be present in an alloy with a first metal (eg, niobium) and a second metal (eg, iron).

Certain suitable compositions contain about 5-70% titanium or zirconium. However, the first metal, and the second
It is preferable to limit metals other than the above metals to no more than about 25 atomic percent of the composition, and more preferably to no more than about 10 atomic percent of the composition.

When carrying out the present invention, whether the solid solution is in the form of a lump or
Alternatively, it is preferable to have a shape with an average particle size of about 1000 μm or more. Solid solutions with particle sizes below this dimension react rapidly, but similar materials outside the scope of the present invention (eg, niobium alone) may also react rapidly. Therefore, the advantage of the present invention is that the lump-like (1sn
(above) can be achieved most noticeably when, for example, a melt or directly cast material is used.

The following specific examples specifically illustrate the present invention:
For comparison, certain metals and alloys outside the scope of the present invention are shown that react only slowly with hydrogen at mild temperatures. It should be understood that various additions, deletions, and modifications to these embodiments are considered to be included within the scope and spirit of the invention as defined by the following claims.

Table 1 Nb 1.43 Q - Tα 1.43 OS CD 1.21 -15.4 FCl 1.2
4 -13.3 FF1 1.23 -14. OF Mn 1.26 -11.9 F crime 1.21
-15.4 FC 1.24 -13.5 S* V 1. ! +2 -78 FGα 1.55
-5.6 F Gm 1.55 -5.6 FS gun 1. ! 1
0 -91 F Atl, 39 -2.8 F Mo 1.66 -4.9 FZr 1.5
5 +8.4 No. 87 1.43 0 S F = Fast S = Slow! In the case of 1Ii1%Cμ, it is slow. Higher amounts of Cu would be faster.

*Vase Example of converting from 0N=12 by dividing by 1.05 1 - Alloy niobium 9 containing 1% of the second metal Iron, cobalt, nickel + <L Vanadium, aluminum, silicon and germanium 1 mol% and water cooled The alloy was produced by arc melting under argon on a copper hearth. Each batch was about 41. These alloys were cast under argon into buttons approximately 10-12 mm in diameter and 7-9 mm high.

Each button was allowed to cool to around room temperature and remelted.

This process is done to ensure homogenization. Repeated 6-4 times. Each button was placed in an A-2 stainless steel boat inside a quartz tube and then connected to the quartz tube vacuum system. Then pump the sample to about 10")
After heating to ℃, it was cooled to room temperature. Hydrogen was introduced until the pressure was about 1 atm. In each case, a rapid pressure drop was observed, and heat was generated, temporarily reaching a temperature of around 150°C (possibly higher in some cases). The buttons were violently crushed into powder during this reaction. Nb 9 9%, 2
The particle size distribution obtained from a 41% alloy is shown as a representative example.

-20+60 mesh (850-250μrIL), 4
5.1%; -60+80 mesh (250-180 μm
), 16.7%; -80+100 mesh (180 to 1
- 1 o O + 325 meshes (150-45 μrrL), 20.1%; and -625 meshes (<45 μm), 10.7%; reactions were generally completed within 6 minutes. The final pressure was about 0.8 atmospheres and the composition was about 0.9 hydrogen/niobium. Trihydrides can be produced using higher hydrogen pressures or by cooling the sample below room temperature.

Example 2 (comparative example) A treatment similar to Example 1 was carried out on an alloy of 90 mol% niobium and 10 mol% titanium and zirconium individually. In some cases, the dissolved metal was actually less than 10%. After pressurizing with hydrogen, no significant hydrogen pressure drop was observed, and after 24 hours at room temperature the pressure was I Q Q
It was maintained at or above kPα.

Example N A 1 +H,2 shown in the first two columns of Table 2? M
The same general treatment as in Example 1 was carried out for each of the xQ and alloys.

The reaction was observed based on the pressure drop and the approximate time marked when the reaction was 80% complete at room temperature. The final product after reaching equilibrium (generally 5-5 minutes) was then analyzed by X-ray diffraction. These times and sets are reported in Table 2.

For example, the first column shows that Nb, 7Cr3 reacts at least 80% within about 140 seconds and 1. The product at equilibrium is N
Is it b9□Cr5H84? show.

Table 2 Or 0.03 140 97 584Or O,
0512095582 Gr O,10120901082Ft O,05
2409558;l' Ft O,10150901080 GO,0,0112099188 GO0,0310097887 GO0,0510095584 Mo 0.20 150 80 20
65Mo O, 30260703045 Ni O, 0116099188 Ni O, 026098289 Ni O, 036097686 Ni O, 056095585 Floor 0.10 180 901074 V O, 10 (80901082 V O, 50<10 0 50. 50 8
0V D,60 160 406064 V O,70S 507060 A/! , 0.10 240 901072St
O,02 (10098285 * Approximately 1 hour Example 4 Six-component alloy Nb1-jc shown in the first six columns of Table 3,
, 7Mxz, were subjected to the same treatment as in Example 6, and the final composition at 80% completion and equilibrium state shown in Table 6 was obtained.
i O,47Ga O,0655047476168Z
r O,25Fg 0.10560652510165
(4 others) Continued from page 1 Priority claim 04/5/1982■United States (US)■3
65119

Claims (1)

[Claims] (lj Hydrogen gas at a temperature of about 0 to 100°C, (a)
a first metal forming a body-centered cubic phase structure selected from the group consisting of niobium, tantalum, and mixtures thereof, and (b) aluminum, cobalt, chromium, iron, dissolved in these body-centered cubic phase structures; reacting with a solid solution consisting of at least 0.5 atom % of a second metal selected from the group consisting of manganese, molybdenum, nickel, copper, vanadium, silicon, germanium, gallium and mixtures thereof, at a temperature mentioned above; and hydrogen at the above temperature and equal pressure.
A method for producing a metal hydride, the reaction rate of which is at least twice the reaction rate of metal and hydrogen. (2) Claim 1, wherein the first metal is niobium
The method described in section. (3) The method according to claim 2, wherein the second metal is vanadium. (4) The solid solution further contains 5 to 70 atomic percent of at least one additional metal selected from the group consisting of zirconium and titanium, and the amount of the additional metal and the second metal can be dissolved together in a body-centered cubic phase structure. 3. The method of claim 2, wherein the method is substantially less than 100%. 3. The method of claim 2, wherein the +b+m2 metal is selected from the group consisting of aluminum, silicon, germanium, gallium and mixtures thereof. (6) Claim 5, wherein the second metal is silicon.
The method described in section. (7) The method of claim 5, wherein the second metal is present in an amount of 1 to 10 atomic percent. (8) The method of claim 1, wherein the second metal is present in an amount of 1 to 10 atomic percent. (9) The temperature is 0 to 50°C, and the solid solution is 1000 μm
The method according to claim w1, wherein the method is in the form of a lump having a particle size of at least 100 mL. 00) The hydrogen gas is present in a gas mixture comprising hydrogen, an inert gas and rigid carbon monoxide, the mixture being substantially free of gases harmful to hydrogenation.
The method described in section.