JP2001010866A - Ceramic sheet and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ceramic sheet which is less apt to generate cracks and spalling, even when receiving large lamination loads and thermal stresses, by controlling the heights of burrs on the periphery of the ceramic sheet to a specific value or less, wherein the heights of the burrs are determined by irradiating the surface of the ceramic sheet with laser light by the use of a laser optical three-dimensional shape measurement device and then three-dimensionally analyzing the reflected light. SOLUTION: The burr heights on the periphery of the ceramic sheet are controlled so that the difference between the highest point and lowest point of the ceramic sheet in an area between the peripheral end and the 3 mm-inner place of the ceramic sheet is ±100 μm or less, preferably ±5 μm or less. The value is desirably reduced by lowering the heights of burrs generated on a punching process, reducing inner stresses generated at the punched site, and further equalizing the releasing speed of a thermal decomposition gas over the whole surface of the ceramic sheet on burning. The ceramic sheet has excellent lamination load resistance and excellent thermal stress resistance which are required for component elements such as a solid electrolytic membrane for a flat plate-like solid electrolyte type fuel battery, and can prevent the generation of cracks and spalling on operations.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic sheet and a method for producing the same, and more particularly to a ceramic sheet and a flat solid electrolyte fuel cell, such as a solid electrolyte membrane, which are less susceptible to cracks and cracks and have a smooth surface. The present invention relates to a ceramic sheet having good quality and excellent stability, and a method for producing the same.

[0002]

2. Description of the Related Art The structure of a flat solid electrolyte fuel cell is as follows.
Basically, a cell stack is formed by vertically stacking a large number of cells each having an anode electrode and a cathode electrode on both surfaces of a solid electrolyte. In this case, the cells are arranged close to each other, and the fuel gas and air are not mixed. A separator (interconnector) is disposed between the cells, and the electrolyte membrane and the peripheral portion of the cell and the separator are sealed and fixed. In addition, when a manifold is provided inside the battery cell, it is sealed and fixed at the peripheral portion thereof.

[0003] This separator is generally made of a heat-resistant alloy or ceramic having a large specific gravity, and has a considerable weight because it is in the form of a considerably thick sheet. Also,
It is desired that the ceramic sheet used as a constituent material of the fuel cell be relatively lightweight and thin. Further, the operating temperature of the solid oxide fuel cell is 800 to
Since the temperature is as high as about 1000 ° C., a large laminating load is applied to the constituent material and a considerable thermal stress is applied.

On the other hand, since ceramic sheets such as zirconia sheets are hard and vulnerable to external forces in the bending direction, irregularities, warpage, etc. occur in the surface of ceramic sheets used as fuel cell constituent materials such as solid electrolyte membranes. If there is undulation or the like, the laminating load or thermal stress concentrates at the location, causing cracks or cracks, and the power generation performance is rapidly reduced.

Accordingly, the present inventors have reduced cracks and cracks due to the above-mentioned loading load and thermal stress of a ceramic sheet used for a solid electrolyte membrane of a fuel cell and the like, with the aim of improving the performance and extending the life of the fuel cell. We have been conducting research for some time, and as a part of that research, we confirmed that if the amount of warpage and maximum undulation height of the sheet were suppressed to a predetermined value or less, the occurrence of cracks and cracks could be suppressed as much as possible,
As previously proposed (Japanese Unexamined Patent Publication Nos. 8-151270 and 8-51
No. 271).

With the ceramic sheet presented in the above publication, even a considerably large-sized sheet can withstand considerable lamination load and thermal stress, so that the power generation capacity as a fuel cell can be greatly increased. It is expected to be a very effective technology for industrial practical use of fuel cells.

However, as the present inventors proceed with further improvement research, the following facts have been gradually clarified. That is, even with the ceramic sheet having a small warpage or undulation disclosed in the above-mentioned publication, cracks and cracks may occur depending on the loading load and the degree of thermal stress. The cause is that a ceramic green sheet is punched into a product shape. It was confirmed that the burrs formed on the peripheral portion of the sheet during the operation had a great effect.

In particular, when a ceramic sheet is used as the electrolyte membrane or the like, the periphery of the sheet is sealed and fixed together with a separator or the like and tightly constrained. In this case, local internal stress is generated at the location, and if a load or thermal stress is applied during operation, cracks and cracks are likely to occur at the location.

In a general method of manufacturing a ceramic sheet, a slurry comprising a ceramic raw material powder, an organic binder, and a dispersion medium is formed into a sheet by a doctor blade method, a calender method, an extrusion method, or the like, which is dried and dried. Is volatilized to obtain a green sheet, which is punched into a predetermined shape and fired to decompose and remove the organic binder and mutually sinter the ceramic powder. It is considered that burrs generated on the periphery of the ceramic sheet substantially remain as they are on the final ceramic sheet and cause product defects.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object to provide a method for manufacturing a flat solid electrolyte fuel cell, such as a peripheral material, such as a solid material. It is an object of the present invention to provide a ceramic sheet that is hardly cracked or cracked even when subjected to a large laminating load or thermal stress, and a method for manufacturing the same, which is intended for a ceramic sheet that is subjected to a large laminating load or thermal stress in a state in which it is restrained .

[0011]

A ceramic sheet according to the present invention which can solve the above-mentioned problems is a laser optical three-dimensional shape measuring device, which irradiates a laser beam to the sheet surface and reflects the reflected light. The burr height of the sheet periphery determined by three-dimensional shape analysis of
It has a gist where it is less than m. This burr height is the difference between the height of the highest point and the lowest point of the sheet between the peripheral edge of the sheet and the inner side of 3 mm, and + is the burr generated on the side irradiated with laser light. In addition,-indicates that burrs are generated on the opposite side.

Another aspect of the present invention specifies a method for industrially and efficiently producing the ceramic sheet, and punches a ceramic green sheet in a direction substantially perpendicular to the sheet surface. The punching step includes a firing step of firing the punched sheet.In the punching step, the cutting edge angle (θ) and the angle (θ) between the sheet side surface of the product and the center line (X) passing through the cutting edge are included. ₁ ), and the relationship of the angle (θ ₂ ) between the surface on the remaining sheet side and the center line (X) passing through the cutting edge is 20 ° ≦
The point is that a punching blade that satisfies θ = θ ₁ + θ ₂ ≦ 70 ° and satisfies θ ₁ ≦ θ ₂ is used and the punching blade moves forward and backward with the punching surface urged by an elastic polymer material. .

The resulting ceramic sheet has a reduced burr height at the periphery of the sheet and is less likely to crack or break due to local concentration of stress as described above. Is extremely useful.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Under the above-mentioned problems, the inventors of the present invention have found that a ceramic sheet used as a constituent material of a plate-shaped solid oxide fuel cell, particularly, has a crack or a crack generated in a peripheral fixed portion or inside. In order to improve the performance of the fuel cell by reducing cracks and extend the service life,
I have been conducting research from various angles.

[0015] As a result, cracks and cracks generated in the peripheral constrained portion sealed and fixed as described above are greatly affected by the burr height of the peripheral portion of the ceramic sheet, and the burr height is reduced by ±
If it is suppressed to 100 μm or less, it is confirmed that cracks and cracks derived from burrs on the periphery are prevented as much as possible,
The present invention has been made.

This is because, as described above, when used in a fuel cell, the periphery of the sheet is strongly restrained by sealing and fixing, so that stress concentrates on burrs having a slight height at the periphery, and cracks and For this reason, the present invention strictly defines the height of burrs at the peripheral portion of the sheet as “± 100 μm or less”. By defining the burr height, cracks and cracks due to stress concentration when a laminating load or thermal stress is applied in a state where the peripheral portion is fixed can be suppressed as much as possible. When it is, its performance can be improved and its life can be greatly increased.

The height of the burrs at the periphery is set to ± 100 μm.
"m or less" is defined as a requirement that can suppress the frequency of occurrence of cracks and cracks in the sheet under the following experimental conditions in consideration of actual use conditions. That is, in the evaluation experiment, with respect to various test sheets having different burr heights, a load of 0.1 to 0.5 kg / cm ² , which is a normal lamination load received when used as a constituent material of a fuel cell, was applied to the room temperature. From 1000 to 1000 ° C in 10 hours.
The operation of holding at 0 ° C. for 1 hour and then lowering the temperature to room temperature
The test was repeated 0 times, and those having a low frequency of cracks and cracks were evaluated as good, and the allowable limit of burrs was determined as described above.

In order to suppress cracks and cracks, the burr height at the periphery of the sheet is preferably ± 50 μm or less, more preferably ± 20 μm or less, and still more preferably ± 10 μm or less.
Particularly preferably, it is ± 5 μm or less.

The burr height can be determined, for example, by using a laser optical three-dimensional shape measuring device, irradiating the sheet surface with laser light, and analyzing the reflected light three-dimensionally. That is, the laser optical three-dimensional shape measurement device, when irradiating a laser beam on the ceramic sheet surface to be measured, focuses on the sheet surface, and when the reflected light is uniformly imaged on the photodiode, the sheet Non-contact type micro tertiary system with a structure in which when the surface is displaced and the image becomes uneven, a signal is issued to immediately resolve the unevenness and the lens is controlled so that the objective lens is always focused on the sheet surface. This is an original shape analysis device, and by detecting the amount of movement, it is possible to detect irregularities on the sheet surface to be measured in a non-contact manner. Its resolution is usually 1μ
m or less, more preferably 0.1 μm or less. By using such a device, the burr height at the sheet peripheral portion can be accurately detected.

There are various causes for increasing the burr height at the peripheral portion of the sheet. The biggest cause is that the shrinkage ratio during firing (usually about 10 to 30%) is obtained from the ceramic green sheet usually formed by a doctor blade. ) Is taken into consideration, and burrs are generated when punching into a predetermined size and shape, or burrs at the peripheral portion are generated when internal stress generated during punching is fired while remaining on the green sheet. Due to non-uniform baking (non-uniform decomposition gas generation rate due to thermal decomposition of the binder component).

Therefore, in order to reduce the burrs at the peripheral edge, the height of the burrs generated during the punching process is reduced as much as possible, and the internal stress generated at the punched portion is reduced as much as possible. It is important to make the release rate of the pyrolysis gas uniform during firing over the entire surface of the sheet.

By the way, a general method of manufacturing a ceramic sheet as described above is manufactured by punching a green sheet manufactured by a doctor blade or the like into a predetermined shape and firing the punched sheet. In order to secure a ceramic sheet that satisfies the burr height defined by the present invention, it is necessary to reduce the burr height as much as possible by first devising the punching process. A punching blade that advances and retreats in a direction substantially perpendicular to the sheet surface of the green sheet is used, and as the punching blade, the cutting edge angle (θ) and the center line (X) passing through the cutting edge and the sheet side surface as a product. angle (theta _1), the relationship of the angle (theta ₂₎ of the center line passing through the surface and the cutting edge of the remainder sheet side (X) is, at _{20 ° ≦ θ = θ 1 +} θ 2 ≦ 70 °, and theta ₁ ≦ theta Use a punching blade that satisfies ₂ . It is desirable to adopt a method in which the punching blade moves forward and backward while the punching surface is urged by the elastic polymer material.

For example, FIGS. 1 to 4 are schematic sectional explanatory views illustrating the structure of a punching member A used in the present invention and a punching method using the same. Is fixed, and a sprout plate 4 made of soft rubber or the like is attached to the tip end side of the hard member 2,
The blade 3 is provided so as not to penetrate the sprout plate 4 and protrude from the front end surface thereof unless the splinter plate 4 is compressed and deformed (see FIG. 1)]. In the illustrated example, in order to further secure the fixing of the green sheet at the time of punching, a structure in which the elastic plate 6 is also laminated on the upper surface of the hard plate 5 in the sheet supporting member B arranged to face the punching member A is described. However, the elastic plate 6 is not always necessary. Then, a green sheet G to be punched is arranged on the support member B to perform a punching operation.

In performing the punching of the green sheet G, the punching member A is relatively approached from the state of FIG. 1 toward the surface of the green sheet G placed on the sheet supporting member B from a substantially vertical direction. . As described above, the blade 3 provided on the punching member A is provided so as not to protrude from the front surface of the splashing plate 4, so that when the punching member A approaches the green sheet G as described above, the sheet G The upper surface of the green sheet G first comes into contact with the sprout plate 4, and the green sheet G is sandwiched between the sprout plate 4 and the elastic plate 6 from above and below (see FIG. 2).

Then, when the punching member A is further lowered, the sprout plate 4 made of an elastic material is compressed and deformed, and the blade 3 projects in the direction of the green sheet G. 4 is urged from both sides by the elastic force due to the elastic deformation of the elastic deformation and the elastic force from the elastic plate 6 to be supported and fixed, and in this state, the cutting is performed by the advancement of the blade 3 (FIG. 3). reference).

After the blade 3 has been punched through the green sheet G, the punching member 1 is retracted to retract the blade 3 from the green sheet G punched portion.
Until the blade 3 is pulled out of the green sheet G, the pinching and fixing state is maintained by the resilience of the spring plate 4 and the elastic plate 6, and the blade 3 is opened after the blade 3 is pulled out (see FIG. 4). : X represents a punched portion in the figure).

That is, the punching and the pulling with the advance and retreat of the blade 3 are as follows.
Since the green sheet G is resiliently held and fixed, not only the reduction of the punching dimensional accuracy due to the positional deviation is prevented, but also the generation of burrs is suppressed as much as possible.

Further, the cutting blade 3 used here is:
As shown in an enlarged manner in FIG. 5, the angle θ ₁ on the sheet G ₁ side as a product is formed to be equal to or acute with the angle θ ₂ on the remaining sheet G ₂ side. As a result, as shown in FIG. 5, the direction of the force that pushes the sheet material produced during punching processing, strongly acts on the theta ₂ side of the formed relatively obtuse blade, theta ₁ side of the blade formed at an acute angle force that pushes the the weakened relatively, burr B ₁ which consequently possible to theta ₁ side is smaller than the burr B ₂ as possible theta ₂ side. Moreover, the sheet G ₁ to be a product
Side has less amount of movement of the sheet material itself than the remainder sheet G ₂ side, the internal stress is smaller product sheet G ₁ side caused by punching, even less modifications derived from the internal stress at the time of firing the This leads to suppression of undulation and dimples generated inside the product sheet.

[0029] That Using punching blade 3 having such a shape, not only can reduce the burr formed on the sheet G ₁ side as a product as much as possible, Kakyu also waviness and dimple after firing It is possible to reduce the size. At this time, the thickness (L) of the blade 3 is made as thin as possible as long as the strength required for punching can be secured, preferably 0.4 to 1.2 mm,
More preferably, if a blade of about 0.7 to 0.9 mm is used, the burr can be further reduced, and the burr height of the peripheral edge of the sheet is defined by the present invention.
The requirement of 100 μm or less, more preferably ± 50 μm or less can be easily satisfied.

FIG. 6 shows a modified example of the punching member A used in the present invention, which is essentially the same as the example shown in FIG. 1 except that a spring plate is provided locally at the position where the blade 3 advances and retreats. .

[0031] As is apparent from the above description, the reason for specifying the structure of the punching blade, in short a movement of the sheet material occurring during punching and balance sheet G ₂ direction mainly of sheet material to the product sheet G ₁ side In order to reduce the amount of overhang and reduce the internal stress, the absolute angles of θ ₁ and θ ₂ are not particularly limited, but it is necessary to reduce the burr height on the product sheet side and to perform the punching work smoothly. And the more preferable product sheet G ₁ side angle θ ₁ is 5 to 55.
°, particularly preferably in the range of 10 to 35 °, the balance sheet G ₂ side angle theta ₂ is 10 to 60 °, more preferably 15
４０40 °, and the total blade edge angle of θ ₁ and θ ₂ is θ in the range of 20 to 70 °, more preferably 30 to 60 °.
Range. The cutting edge 3 _T of the blade 3, it is desirable to be positioned in the product sheets G ₁ side with respect to the thickness center line of the blade 3 as shown in FIG.

The kind of the elastic material used as the spattering plate 4 or the elastic plate 6 is not particularly limited as long as it can fix the green sheet at the time of punching by the elastic force. Various elastically deformable materials such as hard sponge, cork, neoprene rubber, urethane rubber, T-type rubber, and soft vinyl chloride can be used. Among them, hard sponge and urethane rubber are particularly preferable.

The performance of the punching device cannot be specified uniformly because it also varies depending on the thickness and size of the green sheet. However, the maximum pressing force is usually 10 to 100.
Tons, press speed 20-200 s.pm, more generally about 50-100 s.pm, punching stroke 20-200 mm, more usually 30-60 mm
Of the degree. In practicing the present invention, in order to lower the burr height of the peripheral edge of the sheet, it is preferable to increase the pressing pressure and reduce the pressing speed, but it is preferable to adopt the optimal conditions in consideration of productivity and equipment costs. I just need.

The green sheet punched into a predetermined size and shape by the above method is then placed on a shelf plate and fired. In the firing step, decomposition, burning out and sintering of the binder component are uniformly performed. Proceeding is important in suppressing the generation of burrs during firing. The present inventors have confirmed through experiments that the porosity is 15 to 85%, more preferably 3%, when firing the green sheet.
If the green sheet is sandwiched between porous sheets in the range of 0 to 75% and firing is performed, the release of decomposition gas from the entire surface of the green sheet and sintering proceed uniformly, so that burrs generated during firing can be suppressed. As a result, it was confirmed that the burr height could be stably reduced to ± 100 μm or less.

At this time, it is possible to sinter the green sheets one by one while sandwiching the green sheets one by one.
It is advantageous to employ a method in which a plurality of green sheets are alternately overlapped with the porous sheet and sintered simultaneously, so that the sintering operation can be performed more efficiently. In the sintering process,
It is preferable to carry out baking by placing a smooth weight on the surface on the uppermost porous sheet, since a ceramic sheet having a smoother and smaller burr can be obtained in addition to the effect of the weight.

Ceramic used as the material of the ceramic sheet
Zirconia, alumina, titania, aluminum nitride
Minium, borosilicate glass, cordierite, mullite
And various single, mixed or composite oxides.
However, the present invention can be used particularly effectively in a plate-like solid electrolyte type.
Particularly preferred for fuel cell solid electrolyte membranes is
It is a zirconia ceramic.
Alkaline earth metals such as MgO, CaO, SrO, BaO
Group oxide, Y_TwoO_Three, La_TwoO_Three, Ce_TwoO_Three, Pr _TwoO_Three, N
d_TwoO_Three, Sm_TwoO_Three, Eu_TwoO_Three, Gd_TwoO_Three, Tb_TwoO_Three, D
y_TwoO_Three, Ho_TwoO_Three, Er_TwoO_Three, Yb_TwoO_ThreeRare earth gold
Oxides, and Sc_TwoO_Three, Bi_TwoO_Three, In_TwoO_ThreeSuch as
Zirconia-based containing one or more stabilizers
Ceramics, among which other additives such as S
iO_Two, Al_TwoO_Three, Ge_TwoO_Three, SnO_Two, Ta_TwoO_Five, Nb
_TwoO_FiveEtc. may be included.

In addition, CeO_TwoOr Bi_TwoO_ThreeTo Ca
O, SrO, BaO, Y_TwoO_Three, La_TwoO _Three, Ce_TwoO_Three, P
r_TwoO_Three, Nd_TwoO_Three, Sm_TwoO_Three, Eu_TwoO_Three, Gd_TwoO_Three, T
b_TwoO_Three, Dr_TwoO_Three, Ho_TwoO_Three, Er_TwoO_Three, Yb_TwoO_Three, P
bO, WO_Three, MoO_Three, V_TwoO_Five, Ta_TwoO_Five, Nb_TwoO_Fiveetc
Ceria or bis with one or more of
Mass system, and LaGdO_ThreeGallate solid-state electricity
Degraded membranes are also exemplified as preferred.

The constituent materials of the anode electrode sheet include cermets of Ni, Co, Fe, or oxides thereof, and the above-mentioned zirconia and / or ceria.
Furthermore, cermets to which alkaline earth metal oxides such as MgO, CaO, SrO, and BaO, and MgAl ₂ O ₄ are added, and the like, and a constituent material of the cathode electrode sheet have a perovskite-type crystal structure. Lanthanum manganate, lanthanum cobaltate, or these lanthanums are partially substituted with Ca, Sr, etc., or manganese is partially substituted with Co, Fe, Cr, etc., and further, lanthanum and cobalt are partially substituted with Ca, Sr. Sr, Co, Fe
And the like.

Since ceramic sheets used for a solid electrolyte membrane of a fuel cell require higher thermal, mechanical, electrical and chemical properties, it is necessary to satisfy these required properties. , Zirconium oxide (tetragonal and / or cubic zirconia) stabilized with yttrium oxide of 2 to 12 mol%, more preferably 2.5 to 10 mol%, and still more preferably 3 to 8 mol% Recommended as

In particular, when the zirconia sheet is put to practical use as a solid electrolyte membrane for a fuel cell, the sheet thickness should be 10 μm or more, more preferably 50 μm, in order to satisfy the required strength and minimize the electric resistance. With the above, 50
The thickness is preferably 0 μm or less, more preferably 300 μm or less.

The shape of the sheet may be any of a circle, an ellipse, a square, a square having an R (R), and the same circular, elliptical, square, R
It may have one or two or more holes, such as squares having a square. Further, the area of the sheet is 50 cm ² or more, preferably 100 cm ² or more. In addition, this area means the area of the outer peripheral edge including the area of the hole when there is a hole in the sheet.

The method for producing these ceramic sheets is not particularly limited, and a slurry containing a ceramic raw material powder, an organic or inorganic binder and a dispersion medium (solvent), and if necessary, a dispersant or a plasticizer, is added to the slurry by a doctor blade method, a calendar method, or the like. A green sheet is obtained by applying a suitable thickness to a smooth sheet, for example, a polyester sheet by a roll method, an extrusion method or the like, drying and evaporating and removing a dispersant, and obtaining a green sheet by a method as described above. After being punched into pieces, the sheet is placed on a porous setter on a shelf plate sandwiched between porous plates, and is placed at a temperature of about 1000 to 1600 ° C. for 2 to 2 hours.
A method of heating and firing for about 5 hours is employed.

At this time, in order to enhance the surface uniformity of the finished sheet and to reduce burrs, the raw material powder used has an average particle diameter in the range of 0.1 to 0.8 μm and has a uniform particle diameter as much as possible. It is desirable to use a powder having a small particle size distribution, specifically, a powder in which 90% by volume or more of the powder is 5 μm or less.

The kind of the binder used in the present invention is not particularly limited, and a conventionally known organic or inorganic binder can be appropriately selected and used. Examples of the organic binder include ethylene copolymers, styrene copolymers, acrylate and methacrylate copolymers, vinyl acetate copolymers, maleic acid copolymers, vinyl butyral resins, and vinyl acetal resins. And vinyl formal resins, vinyl alcohol resins, waxes, and celluloses such as ethyl cellulose.

Among these, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, cyclohexyl acrylate, 2-ethylhexyl are preferred from the viewpoints of green sheet moldability, punching workability, strength, and thermal decomposition during firing. Alkyl acrylates having an alkyl group having 10 or less carbon atoms such as acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, octyl methacrylate, 2
-Alkyl methacrylates having an alkyl group having 20 or less carbon atoms such as ethylhexyl methacrylate, decyl methacrylate, dodecyl methacrylate, lauryl methacrylate, and cyclohexyl methacrylate; hydroxyalkyl groups such as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate And hydroxyalkyl acrylates or hydroxyalkyl methacrylates, dimethylaminoethyl acrylate, aminoalkyl methacrylates such as dimethylaminoethyl methacrylate, and maleic acid half-esters such as (meth) acrylic acid, maleic acid and monoisopropyl maleate Such as carboxyl group-containing Obtained by polymerizing or copolymerizing at least one mer, the number average molecular weight of 20,000 to 200,000, more preferably 50,
000-100,000 (meth) acrylate-based copolymers are recommended as preferred. These organic binders can be used alone or in combination of two or more as needed. Particularly preferred is isobutyl methacrylate and / or 2-butyl methacrylate.
It is a copolymer of a monomer containing 60% by weight or more of ethylhexyl methacrylate.

As the inorganic binder, zirconia sol, silica sol, alumina sol, titania sol and the like can be used alone or in combination of two or more.

The use ratio of the ceramic raw material powder and the binder is 5 to 30 parts by weight of the latter with respect to 100 parts by weight of the former.
More preferably, the range of 10 to 20 parts by weight is suitable,
If the amount of binder used is insufficient, the strength and flexibility of the green sheet will be insufficient, and if it is too large, not only will the viscosity of the slurry be difficult to adjust, but also the decomposition and release of the binder component during firing will be large. Further, it becomes intense and it becomes difficult to obtain a uniform sheet.

Examples of the solvent used for producing the green sheet include water, alcohols such as methanol, ethanol, 2-propanol, 1-butanol and 1-hexanol, ketones such as acetone and 2-butanone, pentane, and the like. Aliphatic hydrocarbons such as hexane and heptane, aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene, and acetates such as methyl acetate, ethyl acetate and butyl acetate are appropriately selected and used. These solvents can be used alone or in combination of two or more. The amount of these solvents to be used may be appropriately adjusted in consideration of the viscosity of the slurry at the time of forming the green sheet.
It is preferable to adjust so as to be in a range of 0 poise, more preferably 10 to 50 poise.

In preparing the above slurry, a polymer electrolyte such as polyacrylic acid or polyammonium polyacrylate is used to promote deflocculation and dispersion of the ceramic raw material powder.
A dispersant comprising an organic acid such as citric acid or tartaric acid, a copolymer of isobutylene or styrene and maleic anhydride and its ammonium salt or amine salt, a copolymer of butadiene and maleic anhydride and its ammonium salt, etc .; green Plasticizers such as dibutyl phthalate and dioctyl phthalate to provide flexibility to the sheet, glycols such as propylene glycol, and glycol ethers; and surfactants and defoamers. It can be added as needed.

Thus, according to the present invention, by suppressing the burr height of the ceramic sheet, particularly at the peripheral portion thereof, to ± 100 μm or less, excellent lamination resistance can be obtained as a constituent material such as a solid electrolyte membrane for a flat solid electrolyte fuel cell. It has loadability and heat stress resistance, can greatly reduce the occurrence of cracks and cracks during operation and can greatly extend the life, and if the method of the present invention is adopted, such shape characteristics Can be manufactured with high productivity.

[0051]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the following Examples, and the scope of the present invention can be adapted to the above and following points. It is also possible to carry out the present invention with appropriate modifications, all of which are included in the technical scope of the present invention.

Example 1 100 parts by weight of a commercially available 8 mol% yttria-stabilized zirconia powder (trade name "HSY-8.0" manufactured by Daiichi Rare Element Co., Ltd.)
30 parts by weight of a binder made of a methacrylate copolymer (molecular weight: 30,000, glass transition temperature: -8 ° C., solid content concentration: 50% by weight), 2 parts by weight of dibutyl phthalate as a plasticizer, and toluene / isopropyl as a dispersion medium 50 parts by weight of a mixed solvent of alcohol (weight ratio = 3/2) was put in a nylon pot into which zirconia balls having a diameter of 10 mm were charged, and kneaded at about 60 rpm for 40 hours to prepare a slurry.

This slurry was concentrated and defoamed to adjust the viscosity to 30 poise. Finally, the slurry was passed through a 200-mesh filter and then coated on a PET film by a doctor blade method to obtain a green sheet.

A blade was attached to this green sheet on a continuous die-cutting machine (trade name “865B” manufactured by Sakamoto Zoki Co., Ltd.), and a press stroke: 40 mm and a press speed: 80 spm.
And cut into 135 mm square. The blade type is a one-sided blade (manufactured by Nakayama Paper Equipment Co., Ltd.) with a blade angle θ of 57.5 ° and θ _1.
But 26.5 °, θ ₂ is 31 °, the shape is fitted with a new cutter blade of 135mm angle to the plywood, was fitted with a further hard green rubber as wings out sponge (Nakayama Paper Equipment Co., Ltd. trade name "KSA-17") Things.

The obtained green sheet was placed on an alumina shelf plate and baked at 1450 ° C. for 3 hours to obtain a green sheet of about 100 mm.
An 8 mol% yttria-stabilized zirconia sheet having a corner and a thickness of 300 μm was obtained.

Example 2 The green sheet obtained in Example 1 was used with a blade angle θ of 4
135 mm in the same manner as in Example 1 except that 3 °, θ ₁ was 21.5 °, and θ ₂ was 21.5 °, and a blade shape composed of both blades (PET punching blade manufactured by Nakayama Paper Equipment Co., Ltd.) was used. Cut into corners.

A total of five green sheets and a total of six separators are stacked on the alumina shelf plate such that the green sheets are alternately sandwiched one above the other by a separator made of alumina having a porosity of 40%. It was baked in the same manner as in Example 1 to obtain an 8 mol% yttria-stabilized zirconia sheet having a size of about 100 mm square and a thickness of 300 μm.

Example 3 A green sheet was obtained in the same manner as in Example 1 except that a commercially available 3 mol% yttria-stabilized zirconia powder (trade name “HSY-3.0” manufactured by Daiichi Rare Element Co., Ltd.) was used. . This green sheet is cut at a blade edge angle θ of 30 °, θ ₁ of 15 °, θ ₂
Is about 160 mm in outer diameter and 26 m in inner diameter in the same manner as in Example except that a blade shape consisting of two blades mirror-polished at 15 ° is used.
m into a donut shape.

Using the five green sheets, a total of six separators were placed on an alumina shelf plate in the same manner as in Example 2 and calcined in the same manner as in Example 2.
A donut-shaped 3 mol% yttria-stabilized zirconia sheet having a diameter of 20 mm, an inner diameter of about 20 mm, and a thickness of 100 μm was obtained.

Example 4 60% by weight of nickel oxide powder (manufactured by Kishida Chemical Co.) and 8%
A nickel powder was prepared in the same manner as in Example 1 except that a mixed powder containing 40% by weight of a mol% yttria-stabilized zirconia powder (trade name "HSY-8.0" manufactured by Daiichi Rare Element Co., Ltd.) was used and the binder was 13 parts. / Zirconia green sheet was obtained.

The green sheet was protruded from the blade used in Example 1 except that orange rubber (trade name “orenge” manufactured by Nakayama Paper Equipment Co., Ltd.) was used as a sponge.
In the same manner as described above, it was cut into a 175 mm square. The green sheet is sandwiched between upper and lower sheets one by one by a separator made of nickel aluminate spinel having a porosity of 15%.
It is placed on an alumina shelf plate in a stack, and baked at 1350 ° C. for 3 hours.
A zirconia sheet was obtained.

Example 5 A powder obtained by adding 0.5% by weight of magnesium oxide to alumina powder (trade name “AL-160SG” manufactured by Showa Denko KK) was used.
An alumina green sheet was obtained in the same manner as in Example 1.

When the green sheet is set to a cutting edge angle θ of 51
°, θ ₁ is 25.5 °, θ ₂ is 120 mm in the same manner as in Example 1 except that a blade having a two-step blade having a 25.5 ° angle is used.
Cut into corners. This green sheet is placed on an alumina shelf plate and baked at 1575 ° C. for 3 hours to obtain a green sheet of about 100 mm square.
An alumina sheet having a thickness of 630 μm was obtained.

Comparative Example 1 The green sheet obtained in Example 1 was cut with a 135 mm square mold and fired in the same manner as in Example 1 to obtain a sheet having a size of about 100 mm square and a thickness of 300 μm.

Comparative Example 2 The green sheet obtained in Example 1 was cut with the same blade as in Example 1 except that no rubber for spattering was attached, and fired in the same manner as in Example 1 to obtain an approximately 100 mm square. And a sheet having a thickness of 300 μm.

Comparative Example 3 The green sheet obtained in Example 1 was prepared using
Cutting was performed in the same manner as in Example 1 except that a blade having 5 °, θ ₁ of 35.5 °, and θ ₂ of 31 ° was used, and further, sintering was performed in the same manner as in Example 2, thereby obtaining an approximately 100 mm square. , Thickness 30
A sheet of 0 μm was obtained.

Comparative Example 4 A green sheet obtained in the same manner as in Example 3 was used except that a blade having an edge angle θ of 23 °, θ ₁ of 11.5 °, and θ ₂ of 11.5 ° was used. By cutting in the same manner as in Example 3 and further firing in the same manner as in Example 3, the outer diameter is about 120 m.
m, an inner diameter of about 20 mm and a thickness of 100 μm were obtained. However, after cutting 500 shots using this blade mold, the cutting edge became worn and became difficult to cut. The 50
Cutting was performed using a blade after use of 0 shots, and firing was performed in the same manner.

Comparative Example 5 A green sheet obtained in the same manner as in Example 4 was used except that a blade having an edge angle θ of 71 °, θ ₁ of 35.5 °, and θ ₂ of 35.5 ° was used. By cutting in the same manner as in Example 4 and further firing in the same manner as in Example 4, about 150 mm
A nickel / zirconia sheet having a corner and a thickness of 400 μm was obtained.

Comparative Example 6 A green sheet obtained in the same manner as in Example 5 was cut in the same manner as in Example 5 except that a blade having a blade thickness of 1.4 mm was used. In the same manner, firing was performed to obtain an alumina sheet having a size of about 100 mm square and a thickness of 630 μm.

Evaluation Test Example 1 The outer peripheral edge of each sheet obtained in Examples 1 to 5 and Comparative Examples 1 to 6 and 3 mm inside thereof, and the sheets obtained in Examples 3 to 4 and Comparative Examples 4 to 5 Inner peripheral edge and inside 3mm
The surface shape of the laser is measured by a laser optical type three-dimensional shape measuring device (UBM-14 model "UBC-14" micro focus)
(Expert). The main specifications were a semiconductor laser (780 nm) as a light source, a spot system of 1 μm, and a vertical resolution of 0.01 μm, and the burr height was measured at a pitch of 0.1 mm.

Evaluation Test Example 2 Each of the sheets was placed on two alumina plates (trade name “SSA-S” manufactured by Nickart Company) with smooth surfaces and parallelism on an alumina base plate. the load of the sheet per area on the 0.1 kgf / cm ² and 0.5 kgf / cm ²
A shelf-plate-shaped alumina was placed as a weight so that

In this state, the operation of raising the temperature from room temperature to 1000 ° C. over 10 hours, maintaining the temperature at 1000 ° C. for 1 hour, and then lowering the temperature to room temperature was repeated, and the occurrence of cracks and cracks was visually and color checked. Observed.

Table 1 also shows the results of the evaluation tests 1 and 2.

[0074]

[Table 1]

[0075]

The present invention is constituted as described above. By specifying the burr height of the ceramic sheet, particularly at the peripheral portion, the present invention can be applied to a constituent material such as a solid electrolyte membrane for a flat solid electrolyte fuel cell. It has the required excellent laminating weight and heat stress resistance, and can minimize the occurrence of cracks and cracks during operation as a result. As a result, for example, the high performance and the durability life have been greatly improved. A fuel cell or the like can be provided. Moreover, according to the method of the present invention, ceramic sheets having such shape characteristics can be industrially and efficiently produced.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional explanatory view showing a configuration of a punching device employed in the present invention and an example of a punching process.

FIG. 2 is a schematic cross-sectional explanatory view showing a configuration of a punching device employed in the present invention and an example of a punching process.

FIG. 3 is a schematic sectional explanatory view showing a configuration of a punching device employed in the present invention and an example of a punching process.

FIG. 4 is a schematic cross-sectional explanatory view showing a configuration of a punching device employed in the present invention and an example of a punching process.

FIG. 5 is an enlarged sectional explanatory view showing a punching blade employed in the present invention and a punching state.

FIG. 6 is an explanatory sectional view showing another example of the punching device employed in the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Blade type holder 2 Hard member 3 Blade 3 _T cutting edge 4 Splashing plate 5 Hard plate 6 Elastic plate A Punching member B Sheet supporting member G Green sheet L Blade thickness X Center line passing through the cutting edge

Continued on the front page (72) Inventor ▲ Taka ▼ ▲ Saki ▼ Eijiro 992, Nishioki, Okihama-ku, Abashiri-ku, Himeji-shi, Hyogo Nippon Shokubai Co., Ltd. Nippon Shokubai Co., Ltd. (72) Inventor, Koji Nishikawa 992, Nishioki, Akihama-ku, Abashiri-ku, Himeji, Hyogo Prefecture BB11 CC03 DD01 DD08 EE12 EE13 HH00 HH03 5H026 AA06 BB01 BB06 CV02 CX04 EE12 HH03

Claims (3)

[Claims] A burr height at a sheet peripheral portion which is obtained by irradiating a laser beam onto a sheet surface and three-dimensionally analyzing the reflected light using a laser optical three-dimensional shape measuring device is ± 100 μm or less. A ceramic sheet, comprising: 2. The ceramic sheet according to claim 1, which is used for a flat solid electrolyte fuel cell. 3. A method for producing a ceramic sheet, comprising: a punching step of punching a ceramic green sheet in a direction substantially perpendicular to the sheet surface; and a firing step of firing the punched sheet. In the process, the cutting edge angle
(θ), the center line passing through the sheet side surface and the cutting edge (X)
(Θ ₁ ), and the angle (θ ₂ ) between the surface on the remaining sheet side and the center line (X) passing through the cutting edge are: 20 ° ≦ θ = θ ₁ + θ ₂ ≦ 70 ° and θ ₁ ≦ theta ₂ using a punching blade which satisfies the, preparation of the ceramic sheet and performing forward and backward of the punching blade while urging the blanked surface at the elastic polymer material.