阅读说明：本技术 一种用于单电池串联的陶瓷连接板及其制备方法 (Ceramic connecting plate for series connection of monocells and preparation method thereof ) 是由 王绍荣 耿玉翠 李航 李汶颖 于 2021-07-08 设计创作，主要内容包括：本发明公开了一种用于单电池串联的陶瓷连接板及其制备方法,涉及燃料电池技术领域。用于单电池串联的陶瓷连接板,包括依次设置的阴极集流层、陶瓷连接体层和阳极集流层,阴极集流层贴合于陶瓷连接体层的一侧端面,阳极集流层贴合于陶瓷连接体层的另一侧端面。陶瓷连接体层为用于分隔燃料与空气的致密陶瓷隔膜,阴极集流层为用于空气侧气流分配的多孔陶瓷,阳极集流层是由多孔金属或金属筋条形成。该陶瓷连接板在固体氧化物燃料电池运行环境中与相邻的陶瓷和玻璃等材料的热膨胀系数匹配性好,还具有高的电导率。(The invention discloses a ceramic connecting plate for single cell series connection and a preparation method thereof, relating to the technical field of fuel cells. The ceramic connecting plate for the series connection of the monocells comprises a cathode current collecting layer, a ceramic connector layer and an anode current collecting layer which are sequentially arranged, wherein the cathode current collecting layer is attached to one side end face of the ceramic connector layer, and the anode current collecting layer is attached to the other side end face of the ceramic connector layer. The ceramic connector layer is a compact ceramic diaphragm for separating fuel and air, the cathode current collecting layer is porous ceramic for air side airflow distribution, and the anode current collecting layer is formed by porous metal or metal ribs. The ceramic connecting plate has good thermal expansion coefficient matching with adjacent materials such as ceramic, glass and the like in the operating environment of the solid oxide fuel cell, and also has high electrical conductivity.)

1. The ceramic connecting plate for the series connection of the monocells is characterized by comprising a cathode current collecting layer, a ceramic connector layer and an anode current collecting layer which are sequentially arranged, wherein the cathode current collecting layer is attached to one side end face of the ceramic connector layer, and the anode current collecting layer is attached to the other side end face of the ceramic connector layer;

the ceramic connector layer is a compact ceramic diaphragm for separating fuel and air, the cathode current collecting layer is porous ceramic for air side airflow distribution, and the anode current collecting layer is formed by porous metal or metal ribs.

2. The ceramic connecting plate according to claim 1, wherein the ceramic connecting body layer is formed by sintering a ceramic membrane and ceramic frame membranes positioned on two sides of the ceramic membrane after hot-pressing integration;

preferably, two ends of the surface of the ceramic membrane are provided with first gas channels, the surface of each ceramic frame membrane is provided with a second gas channel matched with the first gas channels on the ceramic membrane, the ceramic frame membrane is also provided with a middle opening for distributing reaction gas, and the ceramic membrane at the periphery of the opening is reserved, so that the two ceramic frame membranes are used for reinforcing the periphery of the ceramic membrane;

preferably, the shape of the cathode current collector layer and the anode current collector layer is adapted to the central opening on the ceramic frame membrane.

3. The ceramic connecting plate according to claim 2, wherein the ceramic membrane and the ceramic frame membrane are formed by casting, and the thickness of the casting membrane corresponding to the ceramic membrane and the ceramic frame membrane is 150-400 μm, preferably 200-300 μm.

4. The ceramic connecting plate as claimed in claim 3, wherein the thickness of the casting film corresponding to the cathode current collecting layer is 250-500 μm, preferably 300-400 μm;

preferably, the porosity of the cathode current collector layer is 30 to 50%, preferably 40 to 50%.

5. A method of making a ceramic joint plate according to any of claims 1 to 4, comprising: forming the cathode current collector layer, the ceramic connector layer and the anode current collector layer into an integrated application assembly.

6. The method of claim 5, comprising the steps of:

preparing a casting film belt of a ceramic biscuit in a casting mode, punching and cutting the casting film belt by a die to obtain a ceramic film with a first gas channel and a ceramic frame film with a second gas channel and a middle opening, placing the two ceramic frame films on two sides of the ceramic film to form an assembly body, and carrying out hot pressing and sintering on the assembly body to obtain a ceramic connector body layer;

preparing a porous ceramic biscuit membrane in a tape casting mode, and then carrying out die stamping, cutting and sintering to obtain a cathode collector layer;

and the cathode current collecting layer is stacked on one end face of the ceramic connector layer and sintered to form an integrated middle structure, and the anode current collecting layer is placed on the other end face of the ceramic connector layer and combined to form the ceramic connector layer.

7. The production method according to claim 6, wherein in the production of the ceramic connector layer, an operating pressure in a hot pressing process is 5 to 8MPa, a pressing time is 4 to 6s, a dwell time is 5 to 10min, and a pressing temperature is 70 to 85 ℃;

preferably, the operation pressure in the hot pressing process is 5-6MPa, the pressurizing time is 4-6s, the dwell time is 7-9min, and the pressurizing temperature is 73-77 ℃.

8. The method according to claim 6, wherein in the preparation of the ceramic connection body layer, a sintering schedule used in a sintering process is as follows: firstly heating to 200-plus-300 ℃ for primary heat preservation, heating to 550-plus-650 ℃ for secondary heat preservation, heating to 1100-plus-1300 ℃ for tertiary heat preservation, heating to 1300-plus-1500 ℃ for quaternary heat preservation, and then cooling.

9. The method according to claim 8, wherein a sintering schedule used in the process of preparing the ceramic connection body layer is as follows: heating to 200-300 ℃ at a heating rate of 1-2 ℃/min, preserving heat for 60-120min, heating to 550-650 ℃ at a heating rate of 0.3-0.6 ℃/min, preserving heat for 60-120min, heating to 1100-1300 ℃ at a heating rate of 1.5-2.5 ℃/min, preserving heat for 50-70min, heating to 1300 ℃ at a heating rate of 1-1.5 ℃/min, preserving heat for 180-300min, cooling to 750-850 ℃ at a cooling rate of 3-5 ℃/min, and naturally cooling.

10. The method according to claim 6, wherein the anode current collecting layer is prepared by a process comprising: cutting the porous metal raw material to conform to the shape of the middle opening on the ceramic frame membrane;

preferably, the porous metal feedstock is a Ni felt.

Technical Field

The invention relates to the technical field of fuel cells, in particular to a ceramic connecting plate for single cell series connection and a preparation method thereof.

Background

The Solid Oxide Fuel Cell (SOFC) has high efficiency, wide fuel adaptability and potential carbon dioxide concentration characteristics, and has wide application prospects. Since the operating voltage of each cell is only about 0.8V, the cells are connected in series to form a connection plate of the cell stack. Since the SOFC operates at 650-.

The monocell supported by the anode has lower working temperature and larger thermal expansion coefficient, so the metal connecting plate is generally adopted. The connecting plates are made of high-chromium metal materials, and chromium is volatile at high temperature, so that the cathode of the battery is poisoned and loses activity gradually, and the service life of the battery stack is influenced. Meanwhile, the problem of carbon deposition of the Ni-based anode when using hydrocarbon fuel and the problem of oxidation-reduction degradation of the anode caused by the use of high-concentration steam for ensuring fuel reforming have become bottlenecks that restrict the industrialization thereof. The electrolyte supported SOFC has flexible selectivity in the aspect of electrode materials, few defects and high strength, and can overcome the defects. However, the electrolyte supported SOFC has a high working temperature and a small thermal expansion coefficient, and ordinary metal is difficult to meet the requirements of a connecting plate thereof.

In view of this, the invention is particularly proposed.

Disclosure of Invention

The invention aims to provide a ceramic connecting plate for single cells connected in series and a preparation method thereof, aiming at ensuring the corrosion resistance, the thermal expansion coefficient matching property and the high electrical conductivity of the connecting plate.

The invention is realized by the following steps:

in a first aspect, the invention provides a ceramic connecting plate for series connection of monocells, which comprises a cathode current collecting layer, a ceramic connector layer and an anode current collecting layer, wherein the cathode current collecting layer, the ceramic connector layer and the anode current collecting layer are sequentially arranged;

the ceramic connector layer is a compact ceramic diaphragm for separating fuel and air, the cathode current collecting layer is porous ceramic for air side airflow distribution, and the anode current collecting layer is formed by porous metal or metal ribs.

In a second aspect, the present invention further provides a method for manufacturing a ceramic connecting plate, which is used for manufacturing the ceramic connecting plate, and includes: and forming the cathode current collecting layer, the ceramic connector layer and the anode current collecting layer into an integrated application component.

The invention has the following beneficial effects: the invention utilizes the cathode current collecting layer, the ceramic connector layer and the anode current collecting layer to form a three-layer superposed structure, the cathode current collecting layer is the air side, the anode current collecting layer is the fuel side, and the ceramic connecting plate has good thermal expansion coefficient matching with adjacent materials such as ceramic, glass and the like in the operating environment of the solid oxide fuel cell and also has high electrical conductivity.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a schematic view of a ceramic membrane biscuit;

FIG. 2 is a diagram of a ceramic frame membrane biscuit configuration;

FIG. 3 is a structural view of a ceramic interconnect layer;

FIG. 4 is a schematic view of the exterior of the cathode current collector;

FIG. 5 is a schematic view of the anode current collector layer;

FIG. 6 is a schematic side view of a ceramic connecting plate;

fig. 7 is a schematic view of the front face of the ceramic connecting plate in use.

Description of the main element symbols: 10-a ceramic connector layer; 100-a ceramic membrane; 200-ceramic frame membrane; 101-a first gas channel; 201-a second gas channel; 202-middle opening; 20-a cathode current collector layer; 30-anode current collecting layer.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The inventor improves the material and the preparation process of the connecting plate to obtain the ceramic connecting plate with a special structure, and the ceramic connecting plate has good corrosion resistance, thermal expansion coefficient matching property and high electrical conductivity.

The embodiment of the invention provides a preparation method of a ceramic connecting plate, which comprises the following steps: the cathode current collector layer 20, the ceramic connector layer 10 and the anode current collector layer 30 are formed into an integrated application module, and the specific preparation method of the three layers can adopt the prior art.

The inventor improves the preparation process of the ceramic connecting plate, adopts the methods of tape casting, laminating hot pressing and sintering to manufacture the ceramic connecting plate, and can realize continuous batch production and lower cost because reprocessing after sintering is not needed. The full ceramic structure avoids the oxidation and the performance degradation of the interface of the metal connecting plate, and provides guarantee for realizing the long-life galvanic pile.

Specifically, the method comprises the following steps:

s1 preparation of ceramic connection body layer 10

With reference to fig. 1-3, a casting slurry is formed by mixing preparation raw materials, and a casting film belt is obtained after casting and drying; and then obtaining a ceramic membrane 100 with a first gas channel 101 and a ceramic frame membrane 200 with a second gas channel 201 and a middle opening 202 after punching and cutting through a die, placing the two ceramic frame membranes 200 on two sides of the ceramic membrane 100 to form an assembly body, and carrying out hot pressing and sintering on the assembly body to obtain the ceramic connector layer 10.

Specifically, referring to fig. 1 and 2, the two ends of the surface of the ceramic membrane 100 are provided with first gas channels 101, the surface of each ceramic frame membrane 200 is provided with second gas channels 201 matched with the first gas channels 101 on the ceramic membrane 100, the ceramic frame membrane 200 is further provided with middle openings 202 for distributing reaction gases, and the ceramic membrane around the openings is retained so as to facilitate the reinforcement of the periphery of the ceramic membrane 100 by using the two ceramic frame membranes 200. Since the middle portion of the ceramic connector layer 10 should not be too thick and needs to be dense, the inventors have optimized the specific shapes of the ceramic membrane 100 and the ceramic frame membrane 200.

The ceramic film 100 and the ceramic frame film 200 may be prepared from conventional raw materials, and mainly include ceramic powder, a dispersant, a binder, a plasticizer, a solvent, and the like.

Specifically, the ceramic powder may be Sr_1-xLa_xTiO₃、La_1-xSr_xCr_yM_1-yO₃、La_1-xCa_xCr_yM_1-YO₃Where M ═ Fe or Mn, x ═ 0.2 to 0.3, and y ═ 0.4 to 0.6, composite ceramics may also be formed with some high strength ceramics (e.g., alumina, zirconia, etc.). The dispersant may be a DM-55 alkyd-modified thermoplastic acrylic resin, the binder may be a thermoplastic acrylic resin B-72, the plasticizer may be Benzoflex50, and the solvent may be at least one of butyl acetate and xylene, preferably butyl acetate.

In the practical operation process, the ingredients are prepared into casting slurry, the slurry is cast on a precise casting machine, the casting film band of the ceramic biscuit is obtained by drying, and the thickness of the casting film corresponding to the ceramic film 100 and the ceramic frame film 200 is 150-400 μm, preferably 200-300 μm.

Further, a piece of the biscuit in fig. 1 and 2 pieces of the biscuit in fig. 2 are taken, the biscuit in fig. 2 is respectively placed on two sides of the biscuit in fig. 1, and the upper and lower parts are respectively placed, and the structure in fig. 3 is formed by adopting a hot pressing method. The operation pressure in hot pressing process is 5-8MPa (such as 5MPa, 6MPa, 7MPa, 8MPa, etc.), the pressing time is 4-6s (such as 4s, 5s, 6s, etc.), the pressure maintaining time is 5-10min (such as 5min, 6min, 7min, 8min, 9min, 10min, etc.), and the pressing temperature is 70-85 deg.C (70 deg.C, 75 deg.C, 80 deg.C, 85 deg.C, etc.). In order to further improve the forming effect, the operation pressure in the hot pressing process is 5-6MPa, the pressurizing time is 4-6s, the pressure maintaining time is 7-9min, and the pressurizing temperature is 73-77 ℃.

Further, after the green body after hot pressing is co-sintered, the structure in fig. 3 is formed, and the size is slightly shrunk, so that the dense ceramic connector layer 10 is obtained. The sintering system adopted in the sintering process is as follows: firstly heating to 200-class 300 ℃ for primary heat preservation (to remove residual solvent), heating to 550-class 650 ℃ for secondary heat preservation (to remove raw materials such as adhesive and plasticizer), heating to 1100-class 1300 ℃ for tertiary heat preservation, heating to 1300-class 1500 ℃ for quaternary heat preservation, and then cooling.

Specifically, in the preparation process of the ceramic connecting body layer 10, the sintering schedule adopted in the sintering process is as follows: heating to 200-300 ℃ at a heating rate of 1-2 ℃/min, preserving heat for 60-120min, heating to 550-650 ℃ at a heating rate of 0.3-0.6 ℃/min, preserving heat for 60-120min, heating to 1100-1300 ℃ at a heating rate of 1.5-2.5 ℃/min, preserving heat for 50-70min, heating to 1300 ℃ at a heating rate of 1-1.5 ℃/min, preserving heat for 180-300min, cooling to 750-850 ℃ at a cooling rate of 3-5 ℃/min, and naturally cooling. By further optimizing the temperature control of the sintering process, a dense and excellent-performance ceramic connector layer 10 is formed by sintering.

S2 preparation of cathode current collecting layer 20

With reference to fig. 4, a porous ceramic green sheet is prepared by casting, and then die stamping, cutting and sintering are performed to obtain the cathode collector layer 20. The cathode current collector layer 20 is shaped to fit the central opening 202 in the ceramic frame membrane 200 by cutting.

Specifically, the cathode current collecting layer 20 is prepared by using ceramic powder, dispersant, solvent, pore-forming agent, binder, plasticizer and other raw materials, and by adopting the formula in the prior art, obtaining casting slurry through ball milling, mixing and filtering, casting the slurry on a precision casting machine, and drying to obtain a casting film band of the ceramic biscuit, wherein the thickness of the casting film corresponding to the cathode current collecting layer is 250-500 μm, preferably 300-400 μm.

Specifically, the specific raw materials of the ceramic powder, the solvent, the dispersant, the binder and the plasticizer may be as described in S1, and the pore-forming agent may be graphite, ammonium oxalate, carbonized starch, or the like. The porosity of the finally prepared cathode current collecting layer 20 is controlled to be 30-50%, preferably 40-50% by regulating the amount of the pore-forming agent, and the finally prepared cathode current collecting layer is used for distribution of air flow and current.

Specifically, the sintering schedule is approximately the same as S1, and the time of the secondary heat preservation is increased to 60-120min to burn off the pore-forming agent.

S3, integration

Referring to fig. 5 to 7, the cathode current collector layer 20 is stacked on one end surface of the ceramic connector layer 10 and sintered to form an integrated intermediate structure, and the anode current collector layer 30 is then placed on the other end surface of the ceramic connector layer 10 and combined to form a three-layer structure. And completing airflow distribution and current collection paths on the air side by using the cathode current collecting layer 20, and obtaining a complete application assembly of the ceramic connector by using the anode current collecting layer 30 as a fuel airflow distribution plate.

Specifically, the cathode current collector layer 20 and the anode current collector layer 30 are shaped to fit into the central opening 202 of the ceramic framed membrane 200, and the cathode current collector layer 20 and the anode current collector layer 30 may be placed in the central opening 202 when stacked.

Further, the anode current collecting layer 30 is formed of a porous metal or a metal rib. In some embodiments, the process of preparing the anode current collector layer 30 includes: cutting the porous metal material to conform to the shape of the central opening 202 in the ceramic frame membrane 200; the porous metal feedstock may be a Ni felt. The anode current collector layer 30 can be used for gas flow distribution on the fuel side, and can adopt a flow path formed by porous metal or dense metal ribs, and metal pieces are separately manufactured and used in an embedded mode.

In some embodiments, the cathode current collector layer 20 is first stacked on one end surface of the ceramic connector layer 10, and then is combined with the anode current collector layer 30 by means of bonding or the like.

It is added that the preparation method provided by the embodiment of the invention does not need reprocessing after sintering, so that the ceramic connecting plate can realize continuous batch production, and the cost is not high. The full ceramic structure avoids the oxidation and the performance degradation of the interface of the metal connecting plate, and provides guarantee for realizing the long-life galvanic pile.

The embodiment of the invention also provides a ceramic connecting plate for single cell series connection, please refer to fig. 6-7, and the ceramic connecting plate comprises a cathode current collecting layer 20, a ceramic connector layer 10 and an anode current collecting layer 30 which are sequentially arranged, wherein the cathode current collecting layer 20 is attached to one side end face of the ceramic connector layer 10, the anode current collecting layer 30 is attached to the other side end face of the ceramic connector layer 10, the ceramic connector layer 10 is a dense ceramic diaphragm for separating fuel and air, the cathode current collecting layer is porous ceramic for distributing air flow on the air side, the anode current collecting layer is formed by porous metal or metal ribs, and the ceramic connecting plate can be prepared by the preparation method.

It should be noted that the middle of the ceramic connecting plate is a compact diaphragm which can separate fuel and air and has small resistance, and the periphery is thicker to provide strength and provide proper height for the airflow space; the whole connecting plate is molded before sintering, and machining is not needed after sintering.

It should be noted that, for the sake of illustration, the designs of fig. 6 to 7 and their corresponding components use the sealing of fuel only and the open design of air, but this does not limit the shape of the connection plate. The connecting plate with the full sealing structure is also within the protection scope of the application if the connecting plate is manufactured by adopting the material and the process of the application.

The features and properties of the present invention are described in further detail below with reference to examples.

Example 1

The embodiment provides a preparation method of a ceramic connecting plate, which comprises the following steps:

(1) preparation of ceramic interconnect layer 10

Using La_0.6Sr_0.4Cr_0.5Mn_0.5O₃Mixing with equal amount of 3YSZ to form ceramic powder, casting and drying the mixed raw materials to obtain a casting film belt of the ceramic biscuit, wherein the thickness of the film belt is 300 mum。

The biscuit 1 corresponding to the dense ceramic membrane 100 in fig. 1 and the biscuit 2 corresponding to the dense ceramic frame in fig. 2, the biscuit 1 having the first gas channel 101 and the biscuit 2 having the second gas channel 201 and the intermediate opening 202 are obtained by means of die stamping and cutting. Taking 1 biscuit 1 and 2 biscuits 2, respectively placing the biscuits 2 on two sides of the biscuit 1, and hot-pressing the biscuits respectively one above the other. The hot pressing conditions are as follows: the pressurizing pressure of the hot press is 7MPa, the pressurizing time of the hot press is 5s, the pressure maintaining time of the hot press is 7min, and the pressurizing temperature of the hot press is 80 ℃.

And co-sintering the biscuit subjected to hot pressing to obtain the structure shown in the figure 3, wherein the sintering system is as follows: heating to 250 deg.C at a heating rate of 1 deg.C/min, maintaining for 60min, heating to 600 deg.C at a heating rate of 0.5 deg.C/min, and maintaining for 90 min; heating to 1200 ℃ at the heating rate of 2 ℃/min, preserving heat for 60min, heating to 1400 ℃ at the heating rate of 1 ℃/min, preserving heat for 250min, cooling to 800 ℃ at the cooling rate of 4 ℃/min, and naturally cooling to obtain the sintered compact ceramic connector layer 10.

(2) Preparation of cathode current collector layer 20

Using La_0.6Sr_0.4MnO₃Forming ceramic powder, ball-milling the mixed raw materials for 1h, sieving by a 60-mesh sieve, drying for 30h, and casting to obtain a porous ceramic biscuit membrane, wherein the thickness of the membrane is controlled to be 400 mu m. The porous ceramic biscuit in fig. 4 is obtained by a die stamping and cutting method, and is sintered separately to obtain the cathode collector layer 20, so that the shape of the final cathode collector layer 20 is adapted to the middle opening 202 on the ceramic frame membrane 200.

The firing system was substantially the same as that in (1), except that: after the temperature rises to 600 ℃ at the heating rate, the temperature is kept for 120 min.

(3) Integration

The anode current collecting layer 30 shown in fig. 5, i.e., the anode-side fuel dispersion layer, was obtained by cutting using a Ni felt as a porous metal.

And (3) stacking the cathode current collecting layer 20 on one side end face of the ceramic connector layer 10, sintering to form an integrated intermediate structure, and then placing the anode current collecting layer 30 on the other side end face of the ceramic connector layer 10, and bonding, combining and forming to obtain the ceramic connecting plate.

Through detection: the ceramic connecting plate prepared in the embodiment and the single cell form a stack repeating unit for testing, and the resistor body of the connecting plate is in the high-frequency intercept of the complex impedance spectrum after the test. Comparing with the complex impedance spectrum of the monocell, the surface specific resistance of the connecting plate is judged to be 0.2 omega cm². In this embodiment the fuel side is effectively sealed and the air side is open.

Example 2

This example provides a method for manufacturing a ceramic connecting plate, which is different from example 1 only in that:

the ceramic powder in the step (1) is La_0.6Sr_0.4Cr_0.5Fe_0.5O₃Is a conductive ceramic material, and is compounded with equal amount of 3 YSZ;

in the step (2), the ceramic powder is La_0.6Sr_0.4Co_0.2Fe_0.8O₃。

Through detection: the ceramic connecting plate prepared in the embodiment and the single cell form a stack repeating unit for testing, and the resistor body of the connecting plate is in the high-frequency intercept of the complex impedance spectrum after the test. Comparing with the complex impedance spectrum of the monocell, the surface specific resistance of the connecting plate is judged to be 0.125 omega cm². In this embodiment the fuel side is effectively sealed and the air side is open.

Comparative example:

comparative example provides a method for manufacturing a ceramic connecting plate, which is different from example 1 only in that:

the ceramic powder in the step (1) is Sr_0.7La_0.3TiO₃Is a conductive ceramic material, and is compounded with equal amount of 3 YSZ;

in the step (2), the ceramic powder is La_0.8Sr_0.2MnO₃。

Through detection: the ceramic connecting plate prepared in the embodiment and a monolithic cell form a pile repeating unit for testing, and the connecting plate after testingThe resistor(s) is present in the high frequency intercept of the complex impedance spectrum. Comparing with the complex impedance spectrum of the monocell, the surface specific resistance of the connecting plate is judged to be 0.35 omega cm². In this embodiment the fuel side is effectively sealed and the air side is open.

Comparative examples illustrate that the intrinsic conductivity of the middle dense conductive ceramic membrane and the air-side porous ceramic have a significant effect on the overall effectiveness of the web.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.