JP4866382B2 - Composite metal glass hydrogen separation membrane and method for producing the same - Google Patents

Description

  The present invention relates to a hydrogen separation membrane for hydrogen production, and more particularly to a hydrogen separation membrane (composite metal glass hydrogen separation membrane) mainly composed of a non-Pd metal and a method for producing the same.

In recent years, as one of the countermeasures against global warming, the practical application and popularization of a hydrogen purifier and a fuel cell using the same have been desired. Such a hydrogen purification apparatus has a first chamber and a second chamber, and the first chamber is isolated from the second chamber via a membrane. When a gas containing hydrogen is allowed to flow into the first chamber, the membrane plays a role of substantially permeating hydrogen, and the gas enriched with hydrogen collects in the second chamber, and impurities (CO, CO _2, etc.) are collected. The contained gas remains in the first chamber. Thus, what is called hydrogen permeability is required for the membrane of the hydrogen purifier.
Conventionally, as such a membrane, a palladium alloy (Pd-Ag or the like) foil having hydrogen storage properties has been used. Palladium alloy foils have excellent hydrogen permeability, but palladium is relatively expensive, so there is a need for alternative products made of materials that are less expensive than palladium alloy foils. And the vanadium alloy and the niobium alloy have been examined as an alternative material of a palladium alloy (for example, refer patent documents 1-4).

JP-A-1-262,924 JP-A-4-29,728 Japanese Patent Laid-Open No. 11-276,866 JP 2000-159,503 A

However, all of the alloys described in Patent Documents 1 to 4 are poor in rollability, and when it is attempted to produce an alloy foil by rolling, special rolling conditions and repeated annealing steps are required, resulting in an increase in production cost. . Moreover, when annealing is repeated when producing a foil, the element distribution in the foil may be segregated. Further, such work must be performed in an inert gas atmosphere in order to prevent oxidation of the alloy. However, if the rolling process or annealing process is performed in an inert gas atmosphere, the apparatus becomes large. Moreover, the roll-formed vanadium alloy foil and niobium alloy foil have low toughness and poor workability and durability.
As for niobium alloy foils, it has been known so far to add Ta, Co, Mo, Ni, etc. in order to enhance hydrogen embrittlement resistance (see Patent Document 4 above). In this case, when manufacturing a niobium alloy foil by the cold rolling method, there is a problem that hydrogen permeability is remarkably lowered when the ratio of Ni to niobium exceeds 10 to 20% by weight.

The present invention is a non-Pd-based hydrogen separation membrane (composite metal glass hydrogen separation membrane) that has both high hydrogen permeation performance and hydrogen embrittlement resistance, and material costs and manufacturing costs that are significantly lower than those of current Pd alloy membranes. It is an object to provide a manufacturing method.
The above-described problem is achieved by a hydrogen separation membrane having a composite structure in which Nb, Ta, V, and Ti particles having high hydrogen permeation performance are dispersed in a metallic glass matrix having excellent hydrogen embrittlement resistance and containing Pd as a main component. It is possible to solve.

  That is, the composite metal glass hydrogen separation membrane of the present invention capable of solving the above-described problems is provided with at least one additive element selected from the group consisting of Nb, Ta, V, and Ti particles in the metal glass matrix having an amorphous structure. Has a dispersed structure.

  Further, the present invention provides the composite metal glass hydrogen separation membrane having the above-described characteristics, wherein the metal glass matrix is any one of a Ni-based alloy, a Co-based alloy, and a Cu-based alloy, and the amount of the additive element added is It is also characterized by being 5 to 80% by weight.

  Furthermore, the present invention is a method for producing a composite metal glass hydrogen separation membrane having excellent hydrogen permeation performance and hydrogen embrittlement resistance, the method comprising a metal glass powder as a parent phase, Nb, Ta A composite metal glass bulk material is prepared by mixing at least one additive element selected from the group consisting of V, Ti particles and heating and compressing at a temperature in the vicinity of the supercooled liquid region of the metal glass powder. And a step of thinning the composite metal glass bulk material at a temperature in the vicinity of the supercooled liquid region.

  The hydrogen separation membrane of the present invention comprising a composite structure in which Nb, Ta, V, and Ti particles excellent in hydrogen permeation performance are dispersed in a metallic glass matrix having excellent hydrogen embrittlement resistance has high hydrogen permeation performance and permeation during permeation. It also has excellent hydrogen embrittlement resistance that does not break later, and is useful as a hydrogen separation membrane. Moreover, since expensive Pd is not a main component, there is an advantage that the material cost is low. Furthermore, when the production method of the present invention is used, the above-mentioned composite metal glass hydrogen separation membrane can be produced using a powder metallurgy method that has a proven record in mass production, and the thinning in the supercooled liquid region peculiar to metal glass Since this is possible, it is possible to keep the manufacturing and processing costs low.

In the composite metal glass hydrogen separation membrane of the present invention, at least one additive element selected from the group consisting of Nb, Ta, V, and Ti particles is dispersed in a metal glass matrix having an amorphous structure. Two or more of the above additive elements may be dispersed. At this time, the addition amount of the additive metal needs to be 5 to 80% by weight. For example, in the case of Nb, the preferable addition amount is 10 to 70% by weight, and the addition amount of Nb is smaller than the lower limit value. Then, the permeation performance is low, and a sufficient hydrogen permeation flow rate as a hydrogen separation membrane can be obtained. Conversely, if the amount of Nb added exceeds the above upper limit value, the permeation performance increases, but hydrogen embrittlement occurs in a hydrogen atmosphere. It is easy to cause problems such as breakage during transmission. At the same time, since there are few metallic glass phases that play a role as a binder, it is difficult to obtain a sufficient relative density even if conditions such as temperature and pressure are optimized.
In the present invention, a Ni-based alloy, a Co-based alloy, or a Cu-based alloy is suitable as the metallic glass parent phase to which the additive metal is added, and the specific alloy composition is Ni-Nb-Ti-. Zr-based, Ni-Nb-Zr-based, Co-Zr-Nb-B-based, Co-B-Si-Nb-based, Cu-Zr-Ti-based, Cu-Hf-Ti-based, and the like can be given.

  In the production method of the present invention for producing the above composite metal glass hydrogen separation membrane, in the first step, at least one additive element selected from the group consisting of Nb, Ta, V, and Ti particles, and a parent phase, After mixing the resulting metallic glass powder, the resulting mixture is heated and compressed to produce a composite metallic glass bulk material, but the temperature range at this time is near the supercooled liquid region of the metallic glass used, Desirably, it is 0 to 50 ° C. lower than the glass transition temperature. If the temperature at this time is too low with respect to the glass transition temperature, a sample having a sufficient relative density cannot be produced. Conversely, if the temperature is too high, crystallization of the metallic glass phase is caused, and mechanical properties and There is a high possibility that the transmission performance will be lowered. The pressure at the time of compression after heating is not particularly limited as long as it is a pressure at which a sufficient relative density is obtained, and is preferably 600 MPa or more.

In the present invention, a hot press method or a discharge plasma sintering method as shown in FIG. 1 is suitable as a method for performing the above steps.
In the hot press method shown on the left side of FIG. 1, the above mixture (powder) is packed in a die made of cemented carbide and the like, heated by a heater inside the chamber, and passed through upper and lower punches. A compacted sample is obtained by applying pressure. On the other hand, in the discharge plasma sintering method shown on the right side of FIG. 1, the above-mentioned mixture is packed in a die made of cemented carbide and the like, and a pulse current is applied through upper and lower punches to generate discharge plasma. Powder compacting is performed by the heat generated by the pressure and the pressure applied by the punch. This discharge plasma sintering method has a short heating time compared to the hot pressing method, and a sample having a higher relative density can be obtained at a lower temperature. Therefore, it is convenient for avoiding crystallization of the metallic glass phase. Is considered good.

In the present invention, the following points are mentioned as points for producing a composite metal glass hydrogen separation membrane having excellent hydrogen permeation performance and hydrogen embrittlement resistance.
If the production temperature is too low for the glass transition temperature of the metal glass to be used, the viscous flow of the metal glass cannot be obtained sufficiently, a densely packed sample cannot be obtained, and as a result there is no pinhole. A separation membrane cannot be obtained. On the other hand, if the production temperature is too high, crystallization of the metallic glass phase is caused as described above, and thus it is necessary to set the range in which crystallization does not occur. Therefore, it is considered that there is an optimum temperature range depending on the metal glass used. Further, from the viewpoint of preventing crystallization, the time for compaction is also important, and it is desired not to hold at the maximum temperature for a long time. Desirably, it is necessary to set the production conditions so that the holding time at the maximum temperature is 5 minutes or less. Regarding the pressure, if the pressure is too low, a sufficient relative density cannot be obtained, so it is desirable to use a high pressure. However, since there is a problem that the apparatus becomes large-scale, it is particularly limited in consideration of the balance with the production temperature. do not do.

Next, in the production method of the present invention, in order to make the composite metal glass bulk material obtained by the above hot press method or the discharge plasma sintering method into a product having a film thickness suitable as a hydrogen separation membrane, The film is thinned at a temperature in the vicinity of the cooling liquid region. At this time, the film may be thinned by rolling, or a composite metal glass bulk material is cut out to form a film body having a thickness of about 0.2 to 0.3 mm. After mechanical polishing, the surface may be subjected to Pd surface treatment.
The composite metal glass hydrogen separation membrane of the present invention thus obtained has a high relative density and has a denseness that can be sufficiently used as a hydrogen separation membrane.
EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to these Examples.

Example 1
Cu ₆₀ Zr ₃₀ Ti ₁₀ metal glass powder with an average particle diameter of 20 μm prepared by gas atomization method and commercially available Nb powder were weighed so as to have the ratios shown in Table 1, and then sufficiently mixed using a mortar. The mixed powder was packed in a die made of cemented carbide and set in a furnace of a hot press (HP) apparatus. After evacuation, the temperature was raised in an inert atmosphere by introducing Ar. At 440 ° C. in the vicinity of the supercooled liquid region of Cu ₆₀ Zr ₃₀ Ti ₁₀ metallic glass, the powder was pressed and compacted under pressures of 470 and 780 MPa to obtain a coin-shaped sample having an outer diameter of 20 mm and a height of 5 mm. The obtained sample was subjected to density measurement and structure observation.
As a result, under the condition of a pressure of 470 MPa, No. 2 with a large Nb addition amount was obtained. A sufficient relative density was not obtained with respect to 5, and many voids were observed in the structure observation. On the other hand, at 780 MPa, No. A high relative density of 97% or more was obtained in all the samples 1 to 5, and it was confirmed that the structure had a dense structure even by observing the structure, and it was dense enough to be used as a hydrogen separation membrane. It was confirmed.

(Example 2)
Cu ₆₀ Zr ₃₀ Ti ₁₀ metal glass powder with an average particle diameter of 20 μm prepared by gas atomization method and commercially available Nb powder were weighed so as to have the ratios shown in Table 1, and then sufficiently mixed using a mortar. The mixed powder was packed in a die made of cemented carbide and set in a discharge plasma sintering (SPS) apparatus. The powder was sintered under the conditions of a pressure of 600 MPa at 400 and 420 ° C. in the vicinity of the supercooled liquid region of Cu ₆₀ Zr ₃₀ Ti ₁₀ metallic glass to obtain a coin-shaped sample having an outer diameter of 20 mm and a height of 5 mm. The obtained sample was subjected to density measurement and structure observation. Further, from this sample, a thin disk-shaped sample having a thickness of 0.2 to 0.3 mm was cut out, subjected to mechanical polishing, surface-treated with Pd on the surface, and then subjected to hydrogen permeation by actually permeating hydrogen gas. The permeation performance was evaluated.
FIG. 2 is a graph showing the hydrogen permeation performance of Cu—Zr—Ti + Nb produced by the SPS method, and FIG. 3 is a graph showing the relative density of Cu—Zr—Ti + Nb produced by the HP method and the SPS method.
As a result, at a temperature of 400 ° C., the sample having a high Nb addition amount tended to have a relatively low relative density, but at 420 ° C., a high relative density of 97% or more was obtained. Moreover, when the permeation performance was evaluated, it was found that the Nb addition amount was 40 wt% or more. As for 4 and 5, the permeation performance was not evaluated due to the breakage of the membrane considered to be caused by hydrogen embrittlement, but the samples up to 30 wt% could be evaluated. The permeability coefficient tends to improve as the amount of Nb added increases, and the transmission is 1.1 × 10 ⁻⁸ (mol · m ⁻¹ sec ⁻¹ Pa ^−1/2 ) at 400 ° C., which is the same as that of pure Pd. The coefficient was obtained.

(Example 3)
Ni ₅₃ Nb ₂₀ Ti ₁₀ Zr ₈ Co ₆ Cu ₃ metal glass powder having an average particle diameter of 30 μm prepared by gas atomization method and commercially available V, Nb, Ta powder were weighed to have the ratios shown in Table 2, and then mortar Was mixed well. The mixed powder was packed in a die made of cemented carbide and set in a furnace of a hot press (HP) apparatus. After evacuation, the temperature was raised in an inert atmosphere by introducing Ar. At 540 and 560 ° C. near the supercooled liquid region of Ni ₅₃ Nb ₂₀ Ti ₁₀ Zr ₈ Co ₆ Cu ₃ metallic glass, the powder was pressed and compacted at a pressure of 780 MPa to obtain a coin-shaped sample having an outer diameter of 20 mm and a height of 5 mm. It was. The obtained sample was subjected to density measurement and structure observation. Further, from this sample, a thin disk-shaped sample having a thickness of 0.2 to 0.3 mm was cut out, subjected to mechanical polishing, surface-treated with Pd on the surface, and then subjected to hydrogen permeation by actually permeating hydrogen gas. The permeation performance was evaluated.
As a result, a high relative density of approximately 97% or more was obtained at both temperatures of 540 and 560 ° C. Further, when the permeation performance was evaluated at 500 ° C., the permeation performance was improved with the increase of V, Nb, and Ta, respectively. For the 14 samples, a transmission coefficient of 3.0 × 10 ⁻⁸ (mol · m ⁻¹ sec ⁻¹ Pa ^−1/2 ) was obtained.

  The composite metal glass hydrogen separation membrane of the present invention has high hydrogen permeation performance and excellent hydrogen embrittlement resistance, and material costs and manufacturing costs are significantly lower than current Pd alloy membranes. Useful.

It is a schematic diagram of the hot press method and discharge plasma sintering method used when manufacturing the composite metal glass hydrogen separation membrane of this invention. It is a graph which shows the hydrogen permeation performance of Cu-Zr-Ti + Nb produced by SPS method. It is a graph which shows the relative density of Cu-Zr-Ti + Nb produced by HP method and SPS method. It is a graph which shows the hydrogen permeation performance in 500 degreeC of Ni-Nb-Ti-Zr-Co-Cu + V, Nb, and Ta produced with HP method. It is a graph which shows the relative density of Ni-Nb-Ti-Zr-Co-Cu + V, Nb, and Ta produced by HP method.

Claims (3)

A composite metallic glass hydrogen separation membrane characterized by having a structure in which at least one additive element selected from the group consisting of Nb, Ta, V and Ti particles is dispersed in a metallic glass matrix having an amorphous structure. 2. The composite according to claim 1, wherein the metallic glass matrix phase is any one of a Ni-based alloy, a Co-based alloy, and a Cu-based alloy, and the amount of the additive element added is 5 to 80 wt%. Metallic glass hydrogen separation membrane. A method for producing a composite metal glass hydrogen separation membrane having excellent hydrogen permeation performance and hydrogen embrittlement resistance, the method comprising a metal glass powder as a parent phase and Nb, Ta, V and Ti particles Mixing at least one additive element selected from the group consisting of the above, heating and compressing at a temperature in the vicinity of the supercooled liquid region of the metal glass powder to produce a composite metal glass bulk material, and the composite A method for producing a composite metal glass hydrogen separation membrane, comprising a step of further thinning a metal glass bulk material at a temperature near a supercooled liquid region.