CN1640527A - Preparation method of filter membrane of palladium-based alloy/aperture gradient titanium-aluminum intermetallic compound homogeneous support body for hydrogen separation - Google Patents

Abstract

The invention relates to the production of semi-permeable membranes, and a special preparation method for semi-permeable membranes used in separation processes. It directly forms a sheet or tubular blank by molding or cold isostatic pressing Ti and Al element powders with Ti foil or Al foil, or first forms a sheet or tubular blank by molding or cold isostatic pressing Ti and Al element powders, and then forms a composite blank by Al liquid surface immersion; then prepares a TiAl intermetallic compound pore size gradient homogeneous support body by a two-stage vacuum sintering synthesis method of low-temperature pre-reaction and high-temperature short-time reaction, and then uniformly plates a layer of palladium-based alloy film on its surface by chemical or physical vapor deposition (CVD or PVD), with a thickness of 5 to 50 μm. The membrane prepared in this way has good antioxidant performance, corrosion resistance and mechanical properties, and improves the permeation flux and service life of the hydrogen separation membrane; its TiAl support body can also be directly used as a microfiltration membrane and nanofiltration membrane with excellent performance. The preparation process of the invention does not require the addition of a pore-forming agent, reduces energy consumption, and is almost pollution-free.

Description

Preparation method of filtration membrane of palladium-based alloy/aperture gradient titanium-aluminum intermetallic compound homogeneous support for hydrogen separation

Technical field:

The invention relates to the production of a semi-permeable membrane, a special preparation method for the semi-permeable membrane used in a separation process, and a preparation method for preparing a filter membrane of a hydrogen separation palladium-based alloy and a TiAl intermetallic compound homogeneous support body with a pore size gradient.

Background technique:

Membrane separation technology is driven by external energy or chemical potential difference to separate, classify, purify and enrich the gas or liquid mixed with two or more components. Most of the process has no phase change, and it has high efficiency, energy saving, With the advantages of simple process, less investment and less pollution, it is widely used in various production and research departments of the national economy and in the field of national defense construction. In the field of gas membrane separation, the most widely used is the separation and recovery of hydrogen. At present, the inorganic membranes used for hydrogen separation are mainly metal palladium, silver and their alloy membranes, which can be divided into unsupported membranes and supported membranes according to their structures. The introduction of the support realizes the thinning of the palladium film, reduces the amount of palladium, reduces the cost, improves the permeability of the film, and maintains the high temperature resistance and high mechanical strength of the metal film.

At present, the materials used for the support body for hydrogen separation mainly include: ceramic bodies, such as alumina and glass, and metals such as copper, nickel and stainless steel. The preparation methods used mainly include: preparation of carrier and transition membrane by solid particle sintering method; preparation of ultrafiltration and microfiltration membrane by sol-gel method; preparation of glass membrane by phase separation method; preparation of microporous membrane by chemical vapor deposition and electroless plating. , these methods are complex in process, high in cost, and difficult to control the pore size of the filter membrane; there are disadvantages such as the thermal expansion coefficient mismatch between the material and the palladium membrane, the non-uniform activation of the support surface, the hydrogen embrittlement of the metal, and the brittleness of the ceramic, which makes it difficult to weld and assemble. .

Invention content:

The invention aims to improve the oxidation resistance, corrosion resistance and mechanical properties of the hydrogen separation membrane, increase the permeation flux of the hydrogen separation membrane, prolong its service life, and reduce the cost. The dense composite membrane, and its preparation process is simple, low energy consumption, and pollution reduction.

The present invention adopts following scheme:

Introducing a TiAl intermetallic compound with excellent physical and mechanical properties into a palladium-based alloy membrane support for hydrogen separation to prepare a filter membrane for a homogeneous support of a palladium-based alloy/aperture gradient titanium-aluminum intermetallic compound for hydrogen separation, It is characterized by:

A. Mixture:

The Ti powder with a particle size of 200-10 μm and the Al powder with a particle size of 200-5 μm are uniformly mixed according to the composition distribution ratio of 50-60 at.% Ti and 40-50 at.% Al.

B. Composite forming:

①Using compression molding or cold isostatic pressing, the Ti and Al element powders are directly compounded with Ti foil or Al foil to form a sheet or tubular blank. The specific process is as follows: put Ti foil or Al foil at the end of the punch of a common molding machine, and directly contact with the mixed powder of Ti and Al elements, and form a sheet blank by molding, and the molding pressure is 50-600MPa; or use Cold isostatic pressing method, the pressure is 50-200MPa, the core rod forms a certain taper, the taper is 0.1-2°, the Ti foil or Al foil is placed on the outside of the core rod and in close contact with it, and it is mixed with Ti and Al elements at the same time The powder is in direct contact, and the tubular billet is made by cold isostatic pressing. The thickness of the Ti foil or Al foil is 10-50 μm. A tubular shaped blank with a slightly tapered inner diameter and a thickness of 1 to 3 mm.

② Or first mold Ti, Al element powder or cold isostatic pressing into a sheet or tubular billet, and then make a composite billet by immersing the surface of Al liquid. The surface immersion temperature of Al liquid is 670-900 °C , the immersion time is 0.1-10min, and the thickness of the immersion layer is 0.01-0.5mm.

C. Reactive synthesis:

Through the two-stage vacuum sintering synthesis method of low-temperature pre-reaction and high-temperature short-term reaction, TiAl intermetallic compound pore size gradient homogeneous filtration membrane is prepared. When vacuum pressureless sintering is used, the vacuum degree is 1×10 ^-1 ~ 1×10 ^-3 Pa , the temperature in the low-temperature pre-reaction stage is 500-800°C, and the time is 20-60 minutes; the temperature in the high-temperature short-term reaction stage is 1200-1400°C, and the time is 10-30 minutes; in the cooling stage, the cooling rate is controlled to be 10-50 °C/min.

Or carry out reaction synthesis by low-pressure hot isostatic pressing, the pressure is 0.01-5MPa, the temperature of the low-temperature pre-reaction stage is 500-800°C, and the time is 20-40 minutes; the temperature of the high-temperature short-time reaction stage is 1200-1300°C, and the time is 10 to 20 minutes; in the cooling stage, control the cooling rate to 10 to 50°C/min.

A pore size gradient TiAl intermetallic compound homogeneous support is obtained.

D. The surface of the homogeneous support body of TiAl intermetallic compound is uniformly coated with a layer of palladium-based alloy film by chemical or physical vapor deposition (CVD or PVD), with a thickness of 5-50 μm, and combined into a palladium-based alloy for hydrogen separation /Filtration membrane of gradient TiAl intermetallic compound homogeneous support.

Compared with the prior art, the present invention has the following advantages:

1. Since TiAl intermetallic compound is a lightweight high-temperature structural material, it has excellent mechanical properties, acid and alkali corrosion resistance and oxidation resistance, and its oxidation resistance limit can reach 800-950 ° C. It is used to prepare palladium-based alloy membranes for hydrogen separation By using the support body, the oxidation resistance, corrosion resistance and mechanical properties of the hydrogen separation membrane are greatly improved, the permeation flux of the hydrogen separation membrane is improved, the service life is prolonged, and the production cost is reduced. In addition, due to the thermal expansion coefficient of TiAl intermetallic compounds is 1.1~1.4 (10 ^-5 /K (0 ~ 600 ℃)), which matches the thermal expansion coefficient of metal palladium 1.176 (10 ^-5 /K), which is beneficial to TiAl intermetallic Composite compound pore size gradient homogeneous support and palladium-based alloy membrane.

2. The present invention adopts TiAl intermetallic compound to prepare pore size gradient homogeneous filtration membrane, which is beneficial to control the pore size distribution of the membrane. The pore-forming mechanism of the filter membrane prepared by using Ti and Al element powders is the Kirkendall effect caused by partial diffusion of Al elements. In addition to a certain amount of porosity brought by the powder metallurgy process itself, the Kirkendall effect can cause a 20-30% porosity of the TiAl alloy. By controlling the process conditions: such as Ti, Al powder particle size ratio and composition ratio, reaction synthesis temperature and holding time, etc., can obtain through holes with precisely controlled pore diameters.

3. The compound forming and reaction synthesis of Ti and Al element powders of the present invention are used to prepare palladium-based alloy TiAl intermetallic compound pore size gradient homogeneous supports for hydrogen separation. Due to the Kirkendall effect caused by partial diffusion of Al elements, it can form in the supports. The pore size gradient is from 1-10 μm at the non-composite end to 0.01-0.5 μm at the composite end. The pore size gradient of the material can be controlled by controlling the composite process conditions and sintering process conditions. Therefore, the TiAl intermetallic compound pore size gradient homogeneous filter membrane is also It can be directly used as microfiltration membrane and nanofiltration membrane with excellent performance.

4. In the compound forming and reaction synthesis of Ti and Al element powders of the present invention, in the process of preparing palladium-based alloy TiAl intermetallic compound pore size gradient homogeneous support for hydrogen separation, 40-50% of the pore-forming agent can be obtained without adding pore-forming agents. Porosity avoids the removal of pore-forming agents in the traditional process, reduces energy consumption, and is almost pollution-free.

5. The TiAl intermetallic compound with the composition ratio of the present invention has high microstructure and grain size stability below 1300°C, which ensures the stability of the TiAl inorganic film in use and effectively prevents the poisoning of the palladium film; in addition , The weldability of TiAl intermetallic compounds can also well solve the problem of difficult sealing of ceramics and glass in high temperature environments.

Detailed ways:

Example 1

Ti powder with a particle size of 100-150 μm and Al powder with a particle size of 50-100 μm are used for mixing according to the composition ratio of Ti-46.5at.% Al; then molded under a pressure of 200 MPa, and the Al foil is placed in the The end of the punch of an ordinary molding machine is made into a composite sheet blank with a diameter of 50 mm and a thickness of 1 to 2 mm; the reaction is synthesized by vacuum pressureless sintering, and the vacuum degree is controlled at 1×10 ^-2 to 1×10 ^-3 Pa The low-temperature pre-reaction temperature is 600°C, and the holding time is 60min; the high-temperature short-term reaction temperature is 1300°C, and the holding time is 20min; the cooling rate is controlled at 40°C/min after the reaction; The homogeneous flaky support body has a porosity of 40-45%, an open porosity of 30-35%, and has good oxidation resistance and corrosion resistance. Subsequently, on the surface of the prepared TiAl intermetallic compound support, a layer of palladium-based alloy film was uniformly plated with a thickness of 10 μm by means of physical vapor deposition (PVD).

Example 2

Ti powder with a particle size of 20-50 μm and Al powder with a particle size of 50-100 μm are used for mixing according to the composition ratio of Ti-48at.% Al; then cold isostatic pressing is used to form a tubular billet, and the Al foil is closely attached to the On the outside of the core rod, the taper of the core rod is 0.5°, and the pressure is 150MPa; after a small amount of machining, a composite tubular forming blank with an outer diameter of 30mm, an inner diameter of 28-29mm, and a height of 200mm is obtained; the sintering atmosphere is vacuum, and the vacuum degree Control at 1×10 ^-2 ~ 1×10 ^-3 Pa; low-temperature pre-reaction temperature is 620°C, holding time is 40min; high-temperature short-term reaction temperature is 1260°C, holding time is 30min; after the reaction is completed, the cooling rate is controlled at 30 °C/min; thus, a TiAl intermetallic compound pore size gradient homogeneous tubular support with good permeability is prepared. Subsequently, a layer of palladium-based alloy film was evenly plated on the surface of the prepared TiAl intermetallic compound support body by physical vapor deposition (PVD), with a thickness of 15 μm.

Example 3

Ti powder with a particle size of 150-200μm and Al powder with a particle size of 20-50μm are used for mixing according to the composition ratio of Ti-48.5at.%Al; molded under a pressure of 200MPa to make a diameter of 50mm and a thickness of The 1-2mm flake billet is then made into a composite billet by immersing the surface of Al liquid, the immersion temperature is 700°C, and the immersion time is 2min; the sintering adopts low-pressure hot isostatic pressing, the atmosphere is Ar gas, and the pressure is 0.1MPa, the low-temperature pre-reaction temperature is 620°C, and the holding time is 40min; the high-temperature short-time reaction temperature is 1300°C, and the holding time is 10min. After the reaction is completed, the cooling rate is controlled at 20°C/min; the thus prepared TiAl intermetallic compound pore size gradient homogeneous sheet-like support has a porosity of 35-40%, an open porosity of 25-35%, and a good Oxidation resistance and corrosion resistance. Subsequently, a layer of palladium-based alloy film was evenly plated on the surface of the prepared TiAl intermetallic compound support by physical vapor deposition (PVD), with a thickness of 25 μm.

Example 4

Ti powder with a particle size of 10-40 μm and Al powder with a particle size of 10-40 μm are used for mixing according to the composition ratio of Ti-47at.% Al; cold isostatic pressing is used to form a tubular billet, and the taper of the core rod is 1°. The pressure is 150MPa; after a small amount of machining, a tubular forming blank with an outer diameter of 40mm, an inner diameter of 37.5-38.5mm, and a height of 220mm is produced; then the surface of the outer diameter of the tubular blank is immersed in Al liquid to make a composite Formed billet, the rotation speed of the tubular billet is 0.25rpm, the melting temperature is 720°C, and the melting time is 4min; the sintering atmosphere is vacuum, and the vacuum degree is controlled at 1×10 ^-2 ~ 1×10 ^-3 Pa; low temperature pre-reaction The temperature is 630°C, and the holding time is 30 minutes; the high-temperature short-term reaction temperature is 1300°C, and the holding time is 15 minutes; after the reaction is completed, the cooling rate is controlled at 30°C/min; thus, a TiAl intermetallic compound with a good permeability gradient is obtained. Homogeneous tubular support. Subsequently, a layer of palladium-based alloy film was evenly plated on the surface of the prepared TiAl intermetallic compound support by physical vapor deposition (PVD), with a thickness of 20 μm.

Claims (5)

1. hydrogen separates the preparation method with the filter membrane of palladium-base alloy/bore diameter gradient Intermatallic Ti-Al compound homogeneous supporter, in separating with the palladium-base alloy film support, introduces hydrogen the TiAl intermetallic compound of physical property and mechanical property excellence, method so that preparation hydrogen separates the filter membrane of using palladium-base alloy/bore diameter gradient Intermatallic Ti-Al compound homogeneous supporter is characterized in that:

A. batch mixing:

With the Ti powder of particle diameter 200～10 μ m, the Al powder of particle diameter 200～5 μ m, according to 50～60at.%Ti, the composition proportion of 40～50at.%Al is evenly mixed;

B. combined shaping:

1. adopt the mode of die forming or cold isostatic compaction, with Ti, Al element powders directly and Ti paper tinsel or Al paper tinsel combined shaping, make sheet or tubulose base, detailed process is: the nose of punch that Ti paper tinsel or Al paper tinsel is placed common moulding press, and directly contact with Ti, Al element mixed-powder, make laminar blank by die forming, mold pressing pressure is 50～600MPa; Perhaps adopt the cold isostatic compaction mode, pressure is 50～200MPa, and core bar becomes certain taper, and tapering is 0.1～2 °, Ti paper tinsel or Al paper tinsel are placed the core bar outside and closely contact with it, directly contact with Ti, Al element mixed-powder simultaneously, make the tubulose base by the cold isostatic compaction mode, the thickness of Ti paper tinsel or Al paper tinsel is 10～50 μ m, after the demoulding isostatic cool pressing base external diameter is carried out a small amount of machined, it is even to make external diameter, and internal diameter is tapering slightly, and thickness is the tubulose shaping base of 1～3mm;

2. or earlier be sheet or tubulose base with Ti, Al element powders die forming or cold isostatic compaction, make the combined shaping base by the mode of Al liquid surface infiltration then, Al liquid surface infiltration temperature is 670～900 ℃, and the infiltration time is 0.1～10min, and the infiltration layer thickness is 0.01～0.5mm.

C. reaction is synthetic:

By low temperature pre-reaction and high temperature, short time reaction two-stage vacuum-sintering synthetic method, preparation TiAl intermetallic compound bore diameter gradient homogeneity filtering membrane, when adopting vacuum non-pressure sintering, vacuum is 1 * 10 ^-1～1 * 10 ^-3Pa, the temperature in low temperature pre-reaction stage is 500～800 ℃, the time is 20～60 minutes; The temperature of the high temperature, short time stage of reaction is 1200～1400 ℃, and the time is 10～30 minutes; Cooling stage, the control cooling rate is 10～50 ℃/min.

Perhaps react synthetic by the low pressure high temperature insostatic pressing (HIP), pressure is 0.01～5MPa, and the temperature in low temperature pre-reaction stage is 500～800 ℃, and the time is 20～40 minutes; The temperature of the high temperature, short time stage of reaction is 1200～1300 ℃, and the time is 10～20 minutes; Cooling stage, the control cooling rate is 10～50 ℃/min.

Obtain bore diameter gradient TiAl intermetallic compound homogeneity supporter;

D.TiAl intermetallic compound homogeneity supporting body surface, adopt the method for chemistry or physical vapour deposition (PVD) (CVD or PVD), evenly plate one deck palladium base alloy films, thickness is 5～50 μ m, and being combined into the hydrogen separation is the filter membrane of compound homogeneity supporter with palladium-base alloy/bore diameter gradient TiAl metal.

2. hydrogen according to claim 1 separates the preparation method with the filter membrane of palladium-base alloy/bore diameter gradient Intermatallic Ti-Al compound homogeneous supporter, it is characterized in that:

The employing granularity is that Ti powder and the granularity of 100～150 μ m is the Al powder of 50～100 μ m, carries out batch mixing by the composition proportion of Ti-46.5at.%Al; Die forming under the pressure of 200MPa subsequently places the Al paper tinsel nose of punch of common moulding press simultaneously, and making diameter is 50mm, the compound sheet base of thick 1～2mm; Its sintering atmosphere is a vacuum, and vacuum degree control is 1 * 10 ^-2～1 * 10 ^-3Pa; Low temperature pre-reaction temperature is 600 ℃, and temperature retention time is 60min; The high temperature, short time reaction temperature is 1300 ℃, and temperature retention time is 20min; Cooling velocity was controlled at 40 ℃/min after reaction finished; Zhi Bei TiAl intermetallic compound bore diameter gradient homogeneous sheet supporter thus, porosity is 40～45%, percent opening is 30～35%, has good antioxygenic property and corrosion resistance simultaneously.Subsequently, in prepared TiAl intermetallic compound supporting body surface, adopt the mode of physical vapor deposition (PVD), evenly plate one deck palladium base alloy films, thickness is 10 μ m.

3. hydrogen according to claim 1 separates the preparation method with the filter membrane of palladium-base alloy/bore diameter gradient Intermatallic Ti-Al compound homogeneous supporter, it is characterized in that:

The employing granularity is that Ti powder and the granularity of 20～50 μ m is the Al powder of 50～100 μ m, carries out batch mixing by the composition proportion of Ti-48at.%Al; Adopt cold isostatic compaction tubulose base subsequently, the Al paper tinsel is close to the core bar outside, the core bar tapering is 0.5 °, and pressure is 150MPa; After a small amount of machined, making external diameter is 30mm, and internal diameter is 28～29mm, and height is the composite tube shaping base of 200mm; Sintering atmosphere is a vacuum, and vacuum degree control is 1 * 10 ^-2～1 * 10 ^-3Pa; Low temperature pre-reaction temperature is 620 ℃, and temperature retention time is 40min; The high temperature, short time reaction temperature is 1260 ℃, and temperature retention time is 30min; Cooling velocity was controlled at 30 ℃/min after reaction finished; Make the good TiAl intermetallic compound bore diameter gradient homogeneous tubular support of permeance property thus.Subsequently, in prepared TiAl intermetallic compound supporting body surface, adopt the mode of physical vapor deposition (PVD), evenly plate one deck palladium base alloy films, thickness is 15 μ m.

4. hydrogen according to claim 1 separates the preparation method with the filter membrane of palladium-base alloy/bore diameter gradient Intermatallic Ti-Al compound homogeneous supporter, it is characterized in that:

The employing granularity is that Ti powder and the granularity of 150～200 μ m is the Al powder of 20～50 μ m, carries out batch mixing by the composition proportion of Ti-48.5at.%Al; Die forming under the pressure of 200MPa, making diameter is 50mm, and the laminar blank of thick 1～2mm adopts the mode of Al liquid surface infiltration to make the combined shaping base subsequently, and the infiltration temperature is 700 ℃, and the infiltration time is 2min; Sintering adopts the low pressure high temperature insostatic pressing (HIP), and atmosphere Ar gas, pressure are 0.1MPa, and low temperature pre-reaction temperature is 620 ℃, and temperature retention time is 40min; The high temperature, short time reaction temperature is 1300 ℃, and temperature retention time is 10min.Cooling velocity was controlled at 20 ℃/min after reaction finished; Zhi Bei TiAl intermetallic compound bore diameter gradient homogeneous sheet supporter thus, porosity is 35～40%, percent opening is 25～35%, has good antioxygenic property and corrosion resistance simultaneously.Subsequently, in prepared TiAl intermetallic compound supporting body surface, adopt the mode of physical vapor deposition (PVD), evenly plate one deck palladium base alloy films, thickness is 25 μ m.

5. hydrogen according to claim 1 separates the preparation method with the filter membrane of palladium-base alloy/bore diameter gradient Intermatallic Ti-Al compound homogeneous supporter, it is characterized in that:

The employing granularity is that Ti powder and the granularity of 10～40 μ m is the Al powder of 10～40 μ m, carries out batch mixing by the composition proportion of Ti-47at.%Al; Adopt cold isostatic compaction tubulose base, the core bar tapering is 1 °, and pressure is 150MPa; After a small amount of machined, making external diameter is 40mm, and internal diameter is 37.5～38.5mm, and height is the tubulose shaping base of 220mm; Adopt the mode that tubulose base external diameter surface is carried out Al liquid infiltration to make the combined shaping base subsequently, the rotary speed of tubulose base is 0.25rpm, and the infiltration temperature is 720 ℃, and the infiltration time is 4min; Sintering atmosphere is a vacuum, and vacuum degree control is 1 * 10 ^-2～1 * 10 ^-3Pa; Low temperature pre-reaction temperature is 630 ℃, and temperature retention time is 30min; The high temperature, short time reaction temperature is 1300 ℃, and temperature retention time is 15min; Cooling velocity was controlled at 30 ℃/min after reaction finished; Make the good TiAl intermetallic compound bore diameter gradient homogeneous tubular support of permeance property thus.Subsequently, in prepared TiAl intermetallic compound supporting body surface, adopt the mode of physical vapor deposition (PVD), evenly plate one deck palladium base alloy films, thickness is 20 μ m.