CN100500615C - Improved coating method for preparing membrane of oxide ceramics - Google Patents

Abstract

An improved coating method for preparing an oxide ceramic film relates to a preparation method for an oxide ceramic film. For the advantages and disadvantages of the existing coating method and the slurry spin coating method, the method of the present invention includes the following steps: Step 1: preparation of the support body; Step 2: preparation of the slurry; Step 3: slurry coating Covering; Step 4: Spin coating and leveling; Step 5: Drying of the film blank; Step 6: Repeating Steps 3 to 5; Step 7: High temperature sintering. The invention skillfully combines the advantages of the slurry coating method and the slurry spin coating method, and has the advantages of convenience, quickness, high raw material utilization rate and good film quality. The zirconia electrolyte film prepared by this method is successfully used in the preparation of solid oxide batteries, with high output power density and stable performance.

Description

An improved coating method for preparing oxide ceramic film

technical field

The invention relates to a preparation method of an oxide ceramic film.

Background technique

Generally, oxide ceramic membranes can be prepared by many methods such as coating method, screen printing, sol-gel method, electrophoretic deposition method, dry pressing method, filter coating method, and slurry spin coating method. The background technology directly related to the present invention is the slurry coating method and the slurry spin coating method: the slurry coating method is to directly coat the viscous suspension slurry containing a certain concentration of ceramic powder on the support body to form a membrane base ; And the slurry spin coating method is to drop the suspension slurry with certain fluidity on the support substrate, and the support substrate is sucked on the glue homogenizer, and the glue homogenizer drives the substrate and the slurry droplets on it Rotating at high speed, the centrifugal force is used to rapidly spread the liquid droplets on the support substrate. After a period of time, a liquid film with a certain thickness is formed, and the film blank is formed after drying. The membranes produced by the above two methods are placed in a high-temperature electric furnace together with the support substrate for high-temperature sintering. During the sintering process, attention should be paid to controlling the temperature rise program to ensure the quality of the membrane. The above two methods respectively relate to "A Method for Preparation of Anode Supported Yttria Stabilized Zirconia Electrolyte Membrane" (Application No.: 200410044156.6) and "A Method for Preparing Thin Films by Slurry Spin Coating" (Application No.: 200510010410.5).

Among the above two methods, the coating process is relatively simple. Since high-concentration slurry can be used, the initial density of the membrane blank is high, but the fluidity of the slurry is poor. The coating process requires a certain amount of pressure to assist manual control. The uniformity of film thickness is difficult to control; the slurry spin coating method can make a film with uniform thickness, but the slurry concentration should not be too thick, otherwise it cannot be added dropwise, and it is difficult to unscrew to form a film, and the slurry thrown out during the spin coating process More materials, easy to cause waste of raw materials.

Contents of the invention

In view of the advantages and disadvantages of the above two methods, the present invention provides an improved coating method for preparing an oxide ceramic film, which combines the advantages of the above two methods and effectively avoids the disadvantages of the two methods.

The present invention prepares the oxide ceramic film according to the following steps:

1. Preparation of the support body: After fully mixing and grinding the three raw materials of transition metal oxide, oxide solid solution electrolyte and organic pore-forming agent according to the mass ratio of 5: (3-7): (0.1-5), place in Use 100-500MPa in the mold to press into a disc with a thickness of 0.2-3mm, then place it in a high-temperature electric furnace, raise the temperature to 900-1200°C at a heating rate of 0.5°C/min-20°C/min, and sinter for 0.5-2 hours , that is, to obtain an anode support for the preparation of solid oxide fuel cell electrolyte membrane;

2. Preparation of slurry: mill the ceramic powder of solid solution electrolyte material with a particle size of 0.1-5 microns with a ball mill for 1-48 hours, and then add a binder so that the ceramic powder accounts for 1-60% of the total mass of the slurry. %, then mixed and ball milled together for 0.5 to 10 hours;

3. Slurry coating: apply the above-mentioned slurry to one side of the anode support sheet, and form a coating with a thickness of 10 to 100 microns on the surface;

4. Spin coating and leveling: place the support coated with a thick film of slurry on the turntable of the homogenizer, control the speed of the homogenizer to 2krpm-10krpm, and the homogenization time is 10 seconds to 5 minutes. The surface of the body forms a uniform thin film body with a thinner thickness;

5. Film blank drying: put the film blank in an electric furnace, slowly raise the temperature to 420°C at a rate of 0.5°C/min-100°C/min, bake for 5-10min, and obtain a dry film blank layer;

6. Repeat steps 3 to 5, and measure the thickness of the film each time until the required film thickness is obtained;

7. High-temperature sintering: After repeated coating-spin coating leveling-baking and drying, the multilayer film blank is placed in a high-temperature electric furnace, and the temperature is raised to 1300-1500 °C at a rate of 2 °C/min-10 °C/min, and sintered for 1 ～10h, the dense oxide electrolyte ceramic film supported by the anode is obtained;

The transition group metal oxide in step one refers to a mixture of one or two of nickel oxide, cobalt oxide, copper oxide, iron oxide; the oxide solid solution electrolyte in step one refers to the use of yttrium, scandium, calcium or magnesium Doped zirconia with a cubic or tetragonal structure, or ceria doped with rare earth metal elements or alkaline earth metal elements.

The invention cleverly combines the advantages of the slurry coating method and the slurry spin coating method, and the zirconia electrolyte film prepared by this method is successfully used in the preparation of solid oxide batteries, with high output power density and stable performance. The prepared thin film has micron-level thickness and can be used in the preparation of electrolyte thin film of solid oxide fuel cell (SOFC). The invention has the advantages of convenience, quickness, simple process, uniform film thickness, good film quality, high raw material utilization rate, low cost and the like.

Description of drawings

Figure 1 is a graph of battery output performance results.

Detailed ways

Specific implementation mode 1: This implementation mode adopts the following technical scheme to prepare oxide ceramic membranes:

1. Preparation of the support body: the support body is composed of a mixture of various oxides. The support body used for the oxide electrolyte film of the solid oxide fuel cell is a powder of a transition metal oxide micron or submicron particle size and another A mixture of oxide solid solution solid electrolyte powder and organic pore-forming agent. Transition metal oxide refers to a mixture of one or two of nickel oxide, cobalt oxide, copper oxide, and iron oxide; oxide solid solution electrolyte refers to elements doped with yttrium, scandium, calcium, or magnesium (accounting for 3 to 15 mol%) Doped zirconia with cubic or tetragonal structure, or doped with rare earth metal elements (one or more of Y, Sm, La, Pr, Nd, Gd, etc.) or alkaline earth metal elements (Ca and/or Sr) Cerium oxide; the pore-forming agent is flour, starch, activated carbon or graphite powder with a particle size of 1-50 microns. The above three raw materials of transition group metal oxide, oxide solid solution electrolyte and organic pore-forming agent are fully mixed and ground according to the mass ratio of 5:(3-7):(0.1-5), and then placed in a mold with a pressure of 100-500MPa Press it into a disc with a thickness of 0.2-3mm, then place it in a high-temperature electric furnace, raise the temperature to 900-1200°C at a rate of 0.5°C/min-20°C/min, and sinter for 0.5-2 hours to obtain a solid An anode support prepared from an oxide fuel cell electrolyte membrane.

2. Preparation of coating slurry: slurry preparation includes powder treatment and mixing process with binder. The treatment of the powder is to grind the ceramic powder of oxide solid solution electrolyte materials such as doped zirconia and doped cerium oxide with a particle size of 0.1 to 5 microns with a ball mill for 1 to 48 hours; Organic binders such as base cellulose are dissolved in terpineol, wherein the content of ethyl cellulose is 1-10%; ceramic powder accounting for 1-60% of the total mass is added to the binder, and then mixed together and ball-milled for 0.5 ~10 hours.

3. Coating process: Coating and spin coating to prepare YSZ (Tosoh) film: first transfer the slurry from the storage container to the anode support, and spread the slurry with a scraper, blade or brush to make it One side of the support sheet is completely covered to form a slurry film blank having a thickness of about tens of micrometers. If the slurry is thicker and more viscous, the thickness of the membrane blank may be uneven.

4. Spin coating and leveling: place the support coated with a thick film of slurry on the turntable of the homogenizer, start the vacuum pump suction piece, then set the speed of the homogenizer to 2krpm-10krpm, and set the homogenization time For 10 seconds to 5 minutes, start the glue homogenizer to make the surface of the membrane base flat under the action of centrifugal force, and at the same time make the excess slurry be thrown away from the support by centrifugal force, forming a thinner uniform membrane base on the surface of the support.

5. Drying of the membrane blank: the prepared membrane blank with a certain thickness attached to the support is placed in an electric furnace, and the temperature is slowly raised to 420°C at a rate of 0.5°C/min-100°C/min, and baked for 5-10min. The organic solvent and binder in the film base are volatilized to obtain a dry film base layer.

6. Steps 3 to 5 are repeated, and the thickness of the film is measured every time it is repeated until the required film thickness is obtained.

7. High-temperature sintering: After repeated coating-spin coating leveling-baking and drying, the multilayer film blank is placed in a high-temperature electric furnace, and the temperature is raised to 1300-1500 °C at a rate of 2 °C/min-10 °C/min, and sintered for 1 ~10h, the anode-supported dense oxide electrolyte ceramic film was obtained.

Specific Embodiment 2: In this embodiment, the fabrication of a support for an oxide electrolyte membrane used in a solid oxide fuel cell is taken as an example. The raw materials are nickel oxide (NiO) nanopowder synthesized by glycine-nitrate method, yttria stabilized zirconia (YSZ) electrolyte ceramic powder, and flour for pore-forming agent. The mass ratio of these three raw materials is 5:5:1.7 After the ingredients are fully mixed and ground, they are placed in a mold and pressed at 150-200MPa to form a disc with a thickness of 0.6mm, and then placed in a high-temperature electric furnace, and the temperature is raised to 1000°C at a heating rate of 2°C/min-10°C/min , and sintered for 2 hours to obtain the NiO—YSZ anode support for the preparation of solid oxide fuel cell electrolyte membranes.

Specific Embodiment Three: This embodiment takes the fabrication of a support for an oxide electrolyte membrane used in a solid oxide fuel cell as an example. The raw materials are nickel oxide nano-powder synthesized by precipitation method, samarium oxide-doped cerium oxide (SDC) electrolyte ceramic powder, and flour for pore-forming agent. These three raw materials are mixed and ground in a mass ratio of 5:5:2. Finally, put it in a mold and press it into a disc with a thickness of 0.5mm at 150-200MPa, then place it in a high-temperature electric furnace, raise the temperature to 1000°C at a rate of 2°C/min-10°C/min, and sinter for 2 hours. That is, the NiO—SDC anode support used for the preparation of solid oxide fuel cell electrolyte membranes is obtained.

Embodiment 4: In this embodiment, the coating slurry is prepared according to the following method: place yttria-stabilized zirconia (YSZ) ceramic powder in an alumina grinding jar, add zirconia (ZrO ₂ ) ceramic balls and ethanol solvent , milled for 24 hours with a planetary ball mill. The ethyl cellulose organic binder was dissolved in terpineol, wherein the content of ethyl cellulose was 4%. Add YSZ ceramic powder accounting for 30% of the total mass into the dissolved binder, put it into a grinding jar together with zirconia ceramic balls, and use a ball mill to grind for 2 hours.

Embodiment 5: In this embodiment, the coating slurry is prepared according to the following method: put the SDC powder synthesized by the nitrate citric acid method in an alumina grinding tank, add zirconia ceramic balls and ethanol solvent, and use a planetary ball mill to Ball milled for 36 hours. The ethyl cellulose organic binder was dissolved in terpineol, wherein the ethyl cellulose content was 6%. Add SDC ceramic powder accounting for 40% of the total mass into the dissolved binder, put it into a grinding jar together with zirconia ceramic balls, and use a ball mill to grind for 4 hours.

Embodiment 6: Transfer the slurry prepared according to Embodiment 4 to one side of the support sheet prepared according to the method described in Embodiment 2, and apply it with a scraper to form a 10-50 micron layer on the surface. A thick coating completely covers this surface of the support. Quickly transfer the coated support ceramic sheet to the sample stage of the homogenizer, start the vacuum pump suction piece, then set the speed of the homogenizer to 6krpm, set the homogenization time to 30 seconds, and start the homogenizer , so that the surface of the film base becomes flat under the action of centrifugal force, and at the same time, the excess slurry is thrown away from the support body by centrifugal force, forming a thinner uniform film base body on the surface of the support body. Put the formed membrane base and its support of a certain thickness together in an electric furnace, raise the temperature to 420°C at a rate of 5°C/min, and bake for 5 minutes to volatilize the organic solvent and binder in the membrane base. A dry film blank is obtained. The process of coating-spin coating leveling-film blank drying is repeated three times to obtain a YSZ film with a thickness of 10-15 microns.

Embodiment 7: Transfer the slurry prepared according to Embodiment 5 to one side of the support sheet prepared according to the method described in Embodiment 3, and apply it with a blade to form a 10-50 micron thick layer on the surface. coating, completely covering this surface of the support. Quickly transfer the coated support ceramic sheet to the sample stage of the homogenizer, start the vacuum pump to suck the sheet, then set the speed of the homogenizer to 10krpm, set the homogenization time to 1 minute, and start the homogenizer , so that the surface of the film base becomes flat under the action of centrifugal force, and at the same time, the excess slurry is thrown away from the support body by centrifugal force, forming a thinner uniform film base body on the surface of the support body. Put the formed membrane blank and its support body of a certain thickness together in an electric furnace, raise the temperature to 420°C at a rate of 3°C/min, and bake for 10 minutes to volatilize the organic solvent and binder in the membrane blank. A dry film blank is obtained. The process of coating-spin coating leveling-film blank drying is repeated 5 times to obtain an SDC film with a thickness of 10-20 microns.

Eighth specific embodiment: high temperature sintering. Place the dried NiO—YSZ anode-supported zirconia membrane blank prepared according to Embodiment 6 in a high-temperature electric furnace, raise the temperature to 1400°C at a rate of 5°C/min, and sinter for 4 hours to obtain a NiO—YSZ anode-supported dense YSZ electrolyte ceramic film.

Ninth specific embodiment: high temperature sintering. Place the dried NiO—SDC anode-supported zirconia membrane blank prepared according to Embodiment 7 in a high-temperature electric furnace, raise the temperature to 1350°C at a rate of 3°C/min, and sinter for 8 hours to obtain a NiO—SDC anode-supported dense SDC electrolyte ceramic film.

Embodiment 10: Fuel cell performance test. Coat the surface of the YSZ film supported by the NiO—YSZ anode prepared according to the eighth embodiment by using the sol-gel method to prepare the La _0.7 Sr _0.3 MnO ₃ (LSM) cathode (calcined at 1000°C for 2h), and then at 1100°C After sintering for 2h, the LSM cathode was impregnated with a mixed solution of cerium nitrate and samarium nitrate, and then sintered at 850°C for 1h to make the anode-electrolyte-cathode membrane electrode assembly (MEA) of SOFC. The MEA is packaged at one end of an alumina porcelain tube, in which the NiO—YSZ anode is inside the tube, and the LSM cathode is exposed outside the tube. Each electrode is connected with two silver wires as the lead wires of the electrodes, and the anode inside the tube is purged with nitrogen gas to 700 ℃, pass through hydrogen for reduction, and the cathode is directly exposed to the air. The volt-ampere and power density curves of the battery discharge were tested with the Solartron SI 1287 electrochemical interface at 700°C to 800°C by the four-electrode method, and the battery output performance results are shown in Figure 1. The open circuit voltage of the single cell in this temperature range is above 1V, and the power densities at 700°C, 750°C, and 800°C are 0.671W/cm ² , 0.958W/cm ² , and 1.643W/cm ² , respectively.

Claims (7)

1, a kind of improvement coating method for preparing membrane of oxide ceramics is characterized in that described method is:

One, the preparation of supporter: with transition group metallic oxide, oxide solid solution ionogen and three kinds of raw materials of organic pore-forming agents according to 5:(3～7): after the mass ratio thorough mixing of (0.1～5) grinds, placing mould to be pressed into thickness with 100～500MPa is the thick disk of 0.2～3mm, place high-temperature electric resistance furnace then, temperature rise rate with 0.5 ℃/min～20 ℃/min is warmed up to 900～1200 ℃, sintering 0.5～2 hour promptly obtains being used for the anode support of solid-oxide fuel battery electrolyte film preparation;

Two, the preparation of slurry: granularity is used ball mill ball milling 1～48 hour at the ceramic powder of 0.1～5 micron sosoloid electrolyte, add binding agent then, make ceramic powder account for 1～60% of slurry total mass, the mixed together ball milling is 0.5～10 hour again;

Three, slurry applies: above-mentioned slurry is coated on the one side of anode support sheet, forms the coating of 10～100 micron thickness in its surface;

Four, spin coating leveling: the supporter that will apply the slurry thick film places on the turntable of sol evenning machine, and the rotating speed of control sol evenning machine is 2krpm～10krpm, and the even glue time is 10 seconds～5 minutes, forms the thinner uniform thin film base substrate of thickness in supporting body surface;

Five, film base drying: membrane blank is put in the electric furnace, slowly is warming up to 420 ℃ with the speed of 0.5 ℃/min～100 ℃/min, baking 5～10min obtains exsiccant film base layer;

Six, repeating step three is to step 5, and every thickness that repeats once to survey a film is until obtaining needed film thickness;

Seven, high temperature sintering: place high-temperature electric resistance furnace through coating-spin coating leveling-baking exsiccant multilayer film base repeatedly, speed with 2 ℃/min～10 ℃/min is warming up to 1300～1500 ℃, sintering 1～10 hour obtains the dense oxide electrolyte ceramics film of anode-supported;

Transition group metallic oxide in the step 1 is meant one or both the mixture in nickel oxide, cobalt oxide, cupric oxide, the ferric oxide; Oxide solid solution ionogen in the step 1 is meant with yttrium, scandium, calcium or magnesium are adulterated to have cube or the zirconium white of tetragonal, or thulium or alkali earth metal doping of cerium oxide.

2, a kind of improvement coating method for preparing membrane of oxide ceramics according to claim 1 is characterized in that the powder of described transition group metallic oxide for micron or submicron particle size.

3, a kind of improvement coating method for preparing membrane of oxide ceramics according to claim 1 is characterized in that described thulium is one or more the mixture among Y, Sm, La, Pr, Nd, the Gd.

4, a kind of improvement coating method for preparing membrane of oxide ceramics according to claim 1 is characterized in that described alkali earth metal is Ca and/or Sr.

5, a kind of improvement coating method for preparing membrane of oxide ceramics according to claim 1 is characterized in that described pore-forming material is flour, starch, gac or powdered graphite.

6, a kind of according to claim 1 or 5 improvement coating method for preparing membrane of oxide ceramics, the particle size that it is characterized in that described pore-forming material is 1～50 micron.

7, a kind of improvement coating method for preparing membrane of oxide ceramics according to claim 1 is characterized in that described binding agent is the terpineol solution of ethyl cellulose.

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