JP3100295B2 - Joining method of solid electrolyte made of ceramic material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining a solid electrolyte made of a ceramic material. The method is applied when joining various objects to a solid electrolyte used for an electrolytic cell for tritium purification, an electrolytic cell for hydrogen production, a solid electrolyte type oxygen concentration sensor, a solid battery, and the like. Useful as a method.

[0002]

2. Description of the Related Art One of the uses of certain ceramic materials is as a solid electrolyte. The solid electrolyte is an ionic conductor, which has the property that ions move due to the concentration gradient or potential difference of ions serving as conduction carriers. The solid electrolyte is an electrolytic cell for tritium purification, an electrolytic cell for hydrogen production, and a solid electrolyte type oxygen. It is used for various applications such as concentration measurement sensors and solid state batteries. Conventionally, as a method of hermetically joining various objects to be bonded to a solid electrolyte,
The following methods are mainly known.

(1) Ti-Ni, Zr-Ni, Be-N
i, TiH ₂ -Ni, ZrH ₂ placed a brazing material containing metal or a metal hydride such as -Ni system between the solid electrolyte and the object to be bonded, the metal solder to bond to a heat treatment in a non-oxidizing atmosphere Law.

(2) A paste obtained by mixing an organic binder with a fine powder of Mo, Mo-Mn, W, W-Mn or the like is applied to the surface of a solid electrolyte, and humidified hydrogen or humidified forming gas (H ₂ / N ₂ ) A high melting point metal method in which a Mo or W metal film is formed by heating in Ni, then Ni plating is applied, and the object is brazed using a brazing material.

(3) Ag, Au, Ag-Cu, Pt, P
PbO, Bi for fine powder such as t alloy _TwoO_ThreeAnd SiO_Two
Add fine powder of low melting glass whose main component is
Solid electrolysis of paste made by mixing binder
Applied to the interface between the material and the workpiece and heat-treated in an oxidizing atmosphere
Bonding, or a solid-state
After forming a metal film on the degraded surface, apply Ni plating
Or brazing the workpiece using the brazing material as it is
A mixed metal-oxide solder method.

(4) A between the solid electrolyte and the object
A pressure bonding method in which a foil of u, Ag, Pd, Pt or the like is sandwiched, heated in an oxidizing atmosphere while being pressed, and bonded at a time at a temperature equal to or lower than the melting point of the metal foil.

In any of these joining methods, in any case, the solid electrolyte comes into contact with a metal portion formed by a joining material such as a brazing material or a paste, but the solid electrolyte is an ionic conductor. For example, when the solid electrolyte exhibits oxygen ion conductivity, the interface in contact with the metal functions in the same manner as in a low-oxygen atmosphere, and a phenomenon occurs in which oxygen ions move toward the metal and oxidize the metal. Since the thickness of the oxide film to be formed increases with the elapse of time, there is a problem that the interface between the solid electrolyte and the metal eventually peels off. In particular, when the bonding material contains an easily oxidizable metal element such as Ti or Mo, the problem of peeling due to oxidation of the metal becomes significant. In addition, since the moving speed of oxygen ions increases exponentially with respect to the absolute temperature, the higher the temperature, the faster the oxidation, and when used in a high-temperature environment, there is a problem that the oxygen ions are separated in a short time.

[0008] The conductive ions in the solid electrolyte are
Similarly, in the case of other than oxygen, a phenomenon occurs in which the metal at the contact portion with the solid electrolyte is deteriorated by the conductive carrier.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and uses a joined body in which various materials are joined to a solid electrolyte made of a ceramic material at a high temperature for a long time. In this case, it is a main object of the present invention to provide a solid electrolyte bonding method capable of obtaining a highly reliable bonded body with very little deterioration in bonding strength.

[0010]

The inventor of the present invention has made intensive studies to solve the above-mentioned problems of the prior art. As a result, when an insulating heat-resistant ceramic layer is formed at the joint of a solid electrolyte made of a ceramic material and then an object to be bonded is bonded to the insulating heat-resistant ceramic layer by various airtight bonding means, the ceramic to be bonded is required. Even if is a solid electrolyte, the presence of the insulating heat-resistant ceramic layer effectively prevents the passage of various conductive ions such as oxygen ions, and the resulting bonded body has a bonding strength even when used at high temperatures for a long time. Deterioration is excellent and reliability is excellent, and a mixed ceramic layer obtained by mixing a raw material for a solid electrolyte and a raw material for an insulating heat-resistant ceramic is formed between the solid electrolyte and the insulating heat-resistant ceramic layer. By doing so, thermal stress can be greatly reduced, and a bonded body with less deterioration and excellent durability can be obtained even when used at high temperatures for a long time. The heading, has led to the completion of the present invention here.

That is, according to the present invention, when joining an object to be joined to a solid electrolyte made of a ceramic material, the solid electrolyte material and the insulating heat-resistant ceramic material are mixed at the joint of the solid electrolyte. The present invention relates to a method for bonding a solid electrolyte made of a ceramic material, comprising forming an insulating heat-resistant ceramic layer via a mixed ceramic layer, and then heating and bonding an object to be bonded to the insulating heat-resistant ceramic layer.

The method of the present invention is applied as a method for secretly bonding various objects to a solid electrolyte made of a ceramic material. Examples of the solid electrolyte include oxygen ions, hydrogen ions, Li ions, and Na ions.
Those made of various known ceramic materials using ions, Ag ions or the like as a conductive carrier can be used. The method of the present invention is a highly useful method in that, when a solid electrolyte having oxygen ion conductivity is used among these solid electrolytes, oxidation of a metal material at a bonding portion can be prevented. Such solid electrolytes having oxygen ion conductivity include ZrO ₂ , HfO ₂ , CeO ₂ and ThO.
Examples of the oxide selected from ₂ include a ceramic material composed of an oxide having a fluorite-type crystal structure in which at least one divalent or trivalent metal oxide is dissolved. Among them, in particular, stabilized zirconia in which at least one of CaO, Y ₂ O ₃ and a rare earth oxide is blended with ZrO ₂ as a stabilizer is widely used as an oxygen ion conductive solid electrolyte, It is useful as an object of the method of the present invention. In such stabilized zirconia, the ratio of ion conduction depends on the vacancy concentration of oxygen ions. However, since the amount of addition indicating the maximum vacancy concentration varies depending on the type of the stabilizer, the preferred composition of the stabilized zirconia is Depends on the type of stabilizer. For example, when CaO is used as the stabilizer, the ion transport number of the stabilized zirconia is maximized with an addition amount of 8 to 15 mol%, and when Y ₂ O ₃ is used as the stabilizer, 4 to 10 mol% is used. %, The ion transport number of the stabilized zirconia is maximized. Therefore, these compositions are preferable as a solid electrolyte. However, when CaO is used as a stabilizer, about 6 mol% of Y ₂ O is added. _{When 3} is used as a stabilizer, it can be added up to about 2 mol%.

Other solid electrolytes made of ceramic materials using ions as conduction carriers include HU.
_{O 2 PO 4 · 4H 2 O} ( hydrogen ion conductor), SrCe
_0.95 Yb _0.05 O ₃ (hydrogen ion conductor), LiI-Al
₂ O ₃ (Li ion conductor), Na ₂ O · 11Al ₂ O
₃ (β-alumina, Na ion conductor), Na ₃ Zr ₂
Si ₂ PO ₁₂ (Nasicon, Na ion conductor), AgI
(Ag ion conductor) and RbAg ₄ I ₅ (Ag ion conductor). In the present invention, any of these solid electrolytes can be used.

The object to be joined according to the present invention is not particularly limited, and various metal materials and insulating heat-resistant ceramics as described later can be used according to the application. In addition, a solid electrolyte can be used as an object to be joined. In this case, a mixed ceramic layer and an insulating heat-resistant ceramic layer are also formed on the solid electrolyte as an object to be joined according to a method described later, and an insulating material on the solid electrolyte is formed. By joining the heat-resistant ceramic layers to each other, a method for joining the solid electrolytes can also be used.

In the method of the present invention, first, an insulating heat-resistant ceramic layer is formed at a joint portion of a solid electrolyte via a mixed ceramic layer obtained by mixing the solid electrolyte material and the insulating heat-resistant ceramic material. . As a material for forming the insulating heat-resistant ceramic layer, an oxide of an element other than a transition element having a high valency of 2 or more can be used. Specific examples of such insulating heat-resistant ceramics include Al ₂
Ceramics of oxides such as O ₃ , MgO, SiO ₂ and ZrO ₂ , and MgO · Al which is a two-component system of these oxides
₂ O ₃ (spinel), MgO · SiO ₂ (steatite), 2MgO · SiO ₂ (forsterite), Zr
Ceramics such as O ₂ · SiO ₂ (zircon) can be used. In the insulating heat-resistant ceramic layer, the content of these oxide components is preferably as large as possible, but if the content is about 60% by volume or more, preferably about 70% by volume or more, even when used at a high temperature, In addition, the passage of conduction carriers can be effectively prevented. In the present invention, the mixed ceramic layer obtained by mixing the raw material for the insulating heat-resistant ceramic with the raw material for the solid electrolyte also contains 60% of the oxide component as the raw material for the insulating heat-resistant ceramic.
When the content is at least about volume%, preferably at least about 70 volume%, it can function as an insulating heat-resistant ceramic layer.

In the present invention, a mixed ceramic layer obtained by mixing the raw material for the solid electrolyte and the raw material for the insulating heat-resistant ceramic is formed between the solid electrolyte and the insulating heat-resistant ceramic layer. Due to the presence of the ceramic layer, even when thermal stress is applied to the joined body by heating, cooling, or the like, the thermal stress can be reduced. In particular, when there is a large difference between the thermal expansion coefficient and the firing shrinkage ratio of the two materials in the joined body of the solid electrolyte and the insulating heat-resistant ceramic layer, a tensile stress is applied during heating, cooling or firing, resulting in brittleness. Cracks are likely to occur in the solid electrolyte and insulating heat-resistant ceramics, but the presence of the mixed ceramics layer can significantly reduce thermal stress and prevent cracking of the material.

The mixed ceramics layer may be usually formed in about 1 to 20 layers, but it is preferable to form about 3 to 10 layers in consideration of the reliability of relaxation of thermal stress and the labor of work. When two or more mixed ceramic layers are formed, the amount of the raw material component for the insulating heat-resistant ceramic is increased in the portion closer to the insulating heat-resistant ceramic layer, and the mixed ceramic layer in the portion closer to the solid electrolyte is increased. It is preferable to increase the amount of the raw material component for the solid electrolyte so as to have a so-called gradient composition, so that the coefficient of thermal expansion and the firing shrinkage change almost uniformly from the solid electrolyte to the insulating heat-resistant ceramic. By forming a plurality of mixed ceramic layers so that the thermal expansion coefficient and the firing shrinkage change almost uniformly in this manner, thermal stress is greatly reduced, and cracking of the ceramics can be more effectively prevented.

In the present invention, at the junction of the solid electrolyte,
The method for forming the insulating heat-resistant ceramic layer via the mixed ceramic layer is not particularly limited, and various known methods for forming a ceramic layer can be adopted. The firing method is advantageous in that a simple apparatus is used, and in particular, an expensive apparatus is not required, so that a product can be obtained at low cost.

As a method for forming the mixed ceramics layer and the insulating heat-resistant ceramics layer on the solid electrolyte by the powder lamination method, for example, the following method can be shown. That is, for the raw material powder constituting the solid electrolyte and the raw material powder constituting the insulating heat-resistant ceramic, the raw materials are wet-pulverized so that the powder particle diameter and the forming granule particle diameter are substantially the same, and are adjusted by a spray dryer. Granulate. Regarding the raw materials for the mixed ceramic layer, the respective wet-milled slurries of the raw material powder for the solid electrolyte and the raw material powder for the insulating heat-resistant ceramic are mixed at a predetermined mixing ratio, and then the raw materials for the solid electrolyte are similarly spray-dried. The powder and the raw material powder for insulating heat-resistant ceramics are sized to have substantially the same particle size. The pulverized particle size is desirably about 0.2 to 2 μm, and the granule particle diameter is desirably about 30 to 150 μm.

Next, using each of the molding granules described above,
A predetermined number of granules for forming a mixed ceramics layer are sandwiched between a packing of granules for forming a solid electrolyte and a packing for granules for forming an insulating heat-resistant ceramic, and are integrally formed by a conventional method of forming a ceramic. The molding pressure is usually 500 to 20
It is preferable to be about 00 kgf / cm ² . As a molding method, various methods such as a CIP method, a mechanical press method, a casting method, and an HP method can be adopted. In this case, a molding aid such as a binder is appropriately selected so that the relative densities of the respective molded bodies are substantially the same. It is also desirable to select a sintering aid so that the sintering of the raw materials of each layer proceeds at approximately the same rate. For example, when using stabilized zirconia as a solid electrolyte, the sintering speed can be adjusted by changing the amount of Al ₂ O ₃ , SiO ₂ , a stabilizer, and the like, and Al ₂ O ₃ is used as an insulating heat-resistant ceramic. in case of,
The sintering speed can be adjusted by adding a small amount of MgO, CaO, SiO ₂ or the like.

Next, the solid electrolyte, the mixed ceramic layer and the insulating heat-resistant ceramic layer all have a relative density of 95%.
It is fired at a temperature that sinters to a degree or higher. In this case, it is preferable to lower the heating rate in the temperature range where the sintering rate is different between the layers. In this way, it is possible to obtain a structure in which the insulating heat-resistant ceramic layer is formed at the joint of the solid electrolyte via the mixed ceramic layer.

In the structure obtained by such a powder lamination method, the thickness of the insulating heat-resistant ceramic layer is 0.1%.
The thickness may be about 50 mm, preferably about 0.5 to 20 mm. In addition, the mixed ceramic layer is preferably thick to minimize the thermal stress, but usually, the thickness of one layer may be about 0.1 to 50 mm, and about 0.5 to 20 mm. Is preferred. When two or more mixed ceramic layers are formed,
The thickness of the entire mixed ceramics layer is preferably about 1 to 80 mm.

The mixed ceramics layer and the insulating heat-resistant ceramics layer may be formed at the joint of the solid electrolyte formed in advance by a method such as a CVD method or a thermal spraying method. In this case, the conditions such as the CVD method and the thermal spraying method may be in accordance with a conventional method.
About 10 to 100 μm by CVD, 0.1 to 100 μm by thermal spraying
It is desirable to set it to about 1 mm. The thickness of the insulating heat-resistant ceramic layer is preferably about 10 to 100 μm by the CVD method and about 0.1 to 1 mm by the thermal spraying method. The total thickness of the mixed ceramic layer and the insulating heat-resistant ceramic layer is as follows: It is desirable that the thickness be about 0.1 to 1 mm in the CVD method and about 1 to 5 mm in the thermal spraying method.

In the present invention, an object to be joined is joined to the insulating heat-resistant ceramic layer using the solid electrolyte on which the insulating heat-resistant ceramic layer is formed. As the joining method, various known so-called hermetic joining methods can be applied. According to the specific joining method, a joining material such as a brazing material, a paste, or a metal foil is appropriately selected, and heat joining is performed according to a conventional method. I just need. The following is a detailed description of such a bonding method. Specific conditions in each method may be appropriately determined according to a conventional method.

(1) Metal soldering method: Ti-Ni, Zr
_{-Ni, Be-Ni, TiH 2} -Ni and ZrH ₂ -N
A brazing material containing a metal or metal hydride such as i-type is sandwiched between the insulating heat-resistant ceramic layer and the article to be joined, and the temperature is raised to a temperature slightly higher than the melting point of the brazing material in a vacuum or an inert gas. Heat treatment is performed for about 10 minutes to join both materials at once.

(2) Refractory metal method: Mo, Mo-Mn,
A paste obtained by mixing an organic binder with fine powder of W, W-Mn or the like is applied to the surface of the insulating heat-resistant ceramic layer, and humidified hydrogen or humidified forming gas (H ₂ /
Heated to 1300-1700 ° C. in N ₂ )
Alternatively, after forming a metal film of W, Ni plating is performed and 2
A brazing material such as 8% Cu-72% Ag and 25% Ni-75% Cu is used to braze the workpiece. At this time, when the object to be joined is a ceramic material, the joint portion of the object to be joined may be subjected to M
After forming a metal film of o or W, a Ni plating film is formed in advance.

(3) Metal-oxide mixed solder method: A
g, Au, Ag-Cu, Pt, PbO to a fine powder such as Pt alloy, adding about 1% of fine powder of low-melting glass mainly containing such Bi ₂ O ₃ and SiO _2, it to organic binder The paste obtained by mixing is applied to the interface between the insulating heat-resistant ceramic layer and the object to be joined, and is heated at 450 to 900 ° C. in an oxidizing atmosphere to perform joining at one time. Alternatively, after a metal film is formed on the surface of the insulating heat-resistant ceramic layer by this method, Ni plating is performed, or the brazing material is brazed to the workpiece using a brazing material as it is.
In the joining method using a brazing material, when the object to be joined is a ceramic material, a metal film is formed also on the joint portion of the object to be joined in the same manner as the insulating heat-resistant ceramic layer, and then Ni A plating film is formed in advance.

(4) Crimping method: A foil of Au, Ag, Pd, Pt or the like is sandwiched between the insulating heat-resistant ceramic layer and the object to be bonded, and is pressed in an oxidizing atmosphere at a pressure of about 1 kgf / cm ^2. , 800 to 1200 ° C. for about 10 to 20 hours, and bonding at a time at a temperature equal to or lower than the melting point of the metal foil.

When a solid electrolyte is used as an object to be joined, that is, when solid electrolytes are joined together, a mixed ceramic layer and an insulating heat-resistant ceramic layer are formed on both solid electrolytes by the method described above. What is necessary is just to join the insulating heat-resistant ceramic layers by the various joining methods mentioned above.

In the joined body obtained by the above method,
Since the insulating heat-resistant ceramic layer does not have the property of passing various ions such as oxygen ions, it prevents various conductive ions such as oxygen ions traveling in the solid electrolyte from reaching the contact surface with the metal, and the It works to prevent deterioration.

Further, by forming a mixed ceramic layer obtained by mixing a raw material for a solid electrolyte and a raw material for an insulating heat-resistant ceramic between the solid electrolyte and the insulating heat-resistant ceramic layer, the shrinkage ratio during firing and the heat resistance can be reduced. The expansion coefficient will gradually change, and the thermal stress generated based on the difference in the contraction rate and the thermal expansion coefficient during firing between the solid electrolyte and the insulating heat-resistant ceramic layer can be significantly reduced, It is possible to prevent cracking of the solid electrolyte or heat-resistant ceramic which may occur during firing, heating, or cooling.

One embodiment of the bonding method of the present invention is a bonding method in which the solid electrolyte is a ceramic mainly composed of ZrO ₂ and the insulating heat-resistant ceramic is a ceramic mainly composed of Al ₂ O ₃ . An example will be described.

First, one end is made of a ceramic mainly composed of ZrO ₂ , the other end is made of a ceramic mainly composed of Al ₂ O ₃ , and ZrO 2 extends from one end to the other end.
₂ A ceramic having a gradient composition of ZrO ₂ -Al ₂ O ₃ , in which the Al ₂ O ₃ concentration increases gradually as the concentration decreases sequentially, is manufactured by integrally sintering. Then, various objects to be bonded may be bonded to the ceramics containing Al ₂ O ₃ as a main component of the thus obtained sintered body by the various methods described above. In a sintered body obtained by integrally sintering in this manner, Al ₂ O ₃ does not have a property of passing oxygen ions, and therefore has a role of preventing oxygen ions traveling in ZrO ₂ from reaching the bonding surface. Eggplant ZrO ₂ and Al ₂ O ₃
Is changed to a gradient composition by sequentially changing the concentration.
₂ and Al ₂ O ₃ are different in shrinkage and thermal expansion coefficient during sintering, so that if they are suddenly changed, it is to prevent ceramics from being cracked by thermal stress generated. That is,
This is because, during sintering or heating to a high temperature, the thermal stress generated due to a gradual change in the shrinkage or thermal expansion coefficient is reduced.

[0034]

According to the method for bonding a solid electrolyte made of a ceramic material of the present invention, various types of bonded bodies such as a bonded body of a solid electrolyte and a metal or an insulating heat-resistant ceramic, a bonded body of solid electrolytes, etc. Even if you use it for a long time,
It is possible to obtain a highly reliable bonded body with very little deterioration in bonding strength.

The joining method of the present invention is particularly useful for joining a solid electrolyte and an object to be joined to an electrolytic cell for purifying tritium, an electrolytic cell for producing hydrogen, a sensor for measuring the oxygen concentration of a solid electrolyte, and a solid battery. Useful.

[0036]

EXAMPLES Hereinafter, the features of the present invention will be further clarified by showing Examples and Comparative Examples.

Embodiment 1 Hereinafter, an embodiment of the present invention will be described with reference to FIG.

FIG. 1 is an explanatory view showing a state in which a plurality of mixed ceramic layers having a gradient composition are formed between a solid electrolyte and an insulating heat-resistant ceramic, and a metal is bonded to the mixed ceramic layers. In FIG. 1, one end of the ceramic has a stabilized ZrO ₂ (YS) containing 8 mol% of yttria (Y ₂ O ₃ ).
Z), and the other end on the opposite side is an insulating heat-resistant ceramic 2 made of Al ₂ O ₃ having a purity of 99% or more. Between the solid electrolyte 1 and the insulating heat-resistant ceramics 2 is a mixed ceramics 3 in which YSZ and Al ₂ O ₃ are compounded.
_{This is} a gradient composition material 4 of ₂ O ₃ . The metal 5 was vacuum-brazed on the insulating heat-resistant ceramic 2 side of such a material using an Ag braze 6 containing 2% of Ti.

FIG. 2 is an explanatory diagram showing a detailed composition distribution of the gradient composition material 4. The length of the solid electrolyte 1 made of YSZ is 14 mm (L ₁ ), followed by 7 mixed ceramics 7 having a composition ratio of 12.5 vol% Al ₂ O ₃ /87.5 vol% YSZ. 0.5 mm (L ₂ ), 25
Vol% Al ₂ O _3/75 vol% YSZ mixed ceramics 8 is 14mm composition ratio of 37.5 vol% Al ₂ O ₃ /
7.5 mm mixed ceramics 9 having a composition ratio of 62.5% by volume YSZ, 50% by volume Al ₂ O ₃ /50% by volume YSZ
Mixing ceramic 10 is 14mm in composition ratio, 65 vol% Al ₂ O _3/35 vol% YSZ mixed ceramic 11 composition ratios of 7.5 mm, 80 vol% Al ₂ O _3/20
14 m of mixed ceramics 12 having a composition ratio of volume% YSZ
m, 90% by volume of Al ₂ O _3/10% by volume mixed ceramic 13 of the composition ratio of YSZ is located 7.5 mm, an insulating heat-resistant ceramic 2 of Al ₂ O ₃ at the other end is 1
The length is 4 mm, and the total length (L) is 100 mm.

The overall shape is a cylinder having an outer diameter (L ₄ ) of 2
4mmφ, inner diameter (L ₃ ) is 18mmφ, length is 100m
m. The gradient composition material 4 was manufactured by sequentially laminating powders of each composition in a rubber mold, applying a hydrostatic pressure press in a cold state, and then sintering in the air.

FIG. 3 shows the joint (the present invention) shown in FIG.
It is a graph which shows the result of having measured the joint strength which heated the joined body which brazed the metal with YSZ which is the conventional method with Ag braze containing 2% Ti to 400 degreeC in air, and measured it. FIG.
According to the conventional method, the strength immediately after joining is 5 kg / mm.
^The sample having a value of 2 was peeled by hand after heating at 400 ° C. in the air for 200 hours, that is, the bonding strength was close to zero.

On the other hand, when the gradient composition material of the present invention was used, the strength immediately after joining was 20 kg / mm ² ,
After heating at 400 ° C. in the air for 200 hours and 500 hours, the bonding strength was unchanged, and was 20 kg / mm ² . From this, according to the bonding method of the present invention, the insulating heat-resistant ceramic layer made of Al ₂ O ₃ contained in the gradient composition material 4 serves to prevent the transfer of oxygen ions to the bonding surface, and the bonded body is formed. It has been proved that even when used at a high temperature for a long time, the bonding surface is not oxidized and peeled off.

The reason why the bonding strength immediately after bonding is higher in the present invention than in the conventional method is that the ceramic material near the bonding interface where breakage occurs is YSZ, which has a lower strength in the conventional method, whereas In this case, the strength of Al ₂ O ₃ is high, and this also contributes to the improvement of the reliability as a joined body.

[0044] Example stabilized zirconia raw material powder containing 2 8 mol% Y ₂ O ₃ (Composition: ZrO ₂ 85.7 wt%, Y ₂ O ₃ 13.7 wt%, Al ₂ O ₃ 0.5 wt% And 0.1% by weight of SiO ₂ ) were wet-mixed and pulverized by a ball mill to obtain a slurry for forming a solid electrolyte having an average particle diameter of 0.7 μm. Also,
Al ₂ O ₃ 99.8% by weight, SiO ₂ 0.06% by weight,
Alumina raw material powder composed of 0.05% by weight of MgO and 0.03% by weight of CaO was wet-mixed and pulverized by a ball mill to obtain a slurry for forming an insulating heat-resistant ceramic having an average particle diameter of 0.7 μm. These two types of slurries are mixed with Al ₂ O ₃
/ Stabilized zirconia (volume ratio) = 10/90 (raw material for mixed ceramics layer a), Al ₂ O ₃ / stabilized zirconia (volume ratio) = 25/75 (raw material for mixed ceramics layer b), Al ₂ O ₃ / Stabilized zirconia (volume ratio) = 35
/ 65 (raw material for mixed ceramics layer c), Al ₂ O ₃ /
Stabilized zirconia (volume ratio) = 50/50 (raw material for mixed ceramics layer d), Al ₂ O ₃ / stabilized zirconia (volume ratio) = 65/35 (raw material for mixed ceramics layer e), Al ₂ O ₃ / Stabilized zirconia (volume ratio) = 85
/ 15 (raw material for mixed ceramics layer f) were mixed at a mixing ratio corresponding to each composition to prepare six types of raw material slurries for the mixed ceramics layer. Next, 3% by weight of a wax emulsion was added as a molding aid to each of these slurries, and sieved with a spray dryer to obtain granules for molding. The particle size of these molding granules was in the range of 30-150 μm. Each of the thus obtained granules for molding is successively layered and filled in a rubber mold, and then cold and subjected to a hydrostatic pressure of 1000 kgf / cm.
² and integrally fired at 1600 ° C. for 3 hours in the atmosphere to produce a sintered body. FIG. 4 shows a side view of the obtained sintered body. The sintered body is a mixed ceramic having an outer diameter of 24 mmφ, an inner diameter of 18 mmφ, and a length of 2 mm at one end of a solid electrolyte 14 made of stabilized zirconia containing 8 mol% Y ₂ O ₃ having an outer diameter of 24 mmφ, an inner diameter of 18 mmφ, and a length of 70 mm. Layer 15 is laminated in six layers, and further, an outer diameter of 24 mmφ and an inner diameter of 18 mm
It has a structure in which an insulating heat-resistant ceramic layer 16 made of Al ₂ O ₃ having a diameter of 18 mm and having a length of 18 mm is laminated. In the mixed ceramics layer, a portion in contact with the solid electrolyte 14 has the composition of the mixed ceramics layer a,
On this, the mixed ceramic layers b to f are sequentially laminated, and the mixed ceramic layer f is in contact with the insulating heat-resistant ceramic layer 16.

The insulating heat-resistant ceramic layer 16 of the sintered body thus obtained was coated with an outer diameter of 24 mm, an inner diameter of 18 mm, and a length of 50 mm using an Ag braze containing 2% of Ti.
mm Kovar alloy was brazed in a high temperature vacuum to obtain a joined body of the solid electrolyte and the Kovar alloy.

The airtightness of the joint surface of the joined body was evaluated by measuring the amount of He leak from the inside of the cylindrical tube to the outside using a He leak detector. As a result, the airtightness of the joined portion immediately after the joining exhibited a detection limit of 1 × 10 ⁻⁹ atm · cc / sec or less of the He leak detector, and the detection limit of 1 × 10 ⁹ after holding at 270 ° C. in the air for 4000 hours. ^-9 atm · cc / sec or less, and airtightness was maintained.

Example 3 A stabilized zirconia raw material powder containing 8 mol% of Y ₂ O ₃ (composition: 86.5% by weight of ZrO _2, 13.4% by weight of Y ₂ O ₃ ) was mixed and pulverized by a ball mill in a wet manner. Thus, a slurry for forming a solid electrolyte having an average particle diameter of 0.3 μm was obtained. Also,
MgO.Al ₂ O ₃ 99.9% by weight, SiO ₂ 0.04
MgO.% By weight and 0.03% by weight of Fe ₂ O ₃
The Al ₂ O ₃ raw material powder was wet-mixed and pulverized by a ball mill to obtain a slurry for forming an insulating heat-resistant ceramic having an average particle diameter of 0.3 μm. These two types of slurries are mixed with MgO
Al ₂ O ₃ / stabilized zirconia (volume ratio) = 10/90
(Raw material for mixed ceramics layer a), MgO.Al ₂ O ₃
/ Stabilized zirconia (volume ratio) = 25/75 (raw material for mixed ceramics layer b), MgO.Al ₂ O ₃ / stabilized zirconia (volume ratio) = 35/65 (raw material for mixed ceramics layer c), MgO. Al ₂ O ₃ / stabilized zirconia (volume ratio) = 50/50 (raw material for mixed ceramics layer d), MgO · Al ₂ O ₃ / stabilized zirconia (volume ratio) = 65/35 (raw material for mixed ceramics layer e) ), M
gO.Al ₂ O ₃ / stabilized zirconia (volume ratio) = 85
/ 15 (raw material for mixed ceramics layer f) were mixed at a mixing ratio corresponding to each composition to prepare six types of raw material slurries for the mixed ceramics layer. Next, 3% by weight of a wax emulsion was added to these slurries as a molding aid, and the mixture was sized with a spray drier to obtain molding granules. The particle size of these molding granules was in the range of 30-150 μm.
Using the respective molding granules thus obtained, a sintered body having the same structure as that of the sintered body obtained in Example 2 was produced in the same manner as in Example 2. In this sintered body, the portion of the mixed ceramics layer that is in contact with the solid electrolyte has the composition of the mixed ceramics layer a, and the mixed ceramics layers b to f are sequentially laminated. The structure is in contact with the layer.

Tungsten having an outer diameter of 24 mmφ, an inner diameter of 18 mmφ, and a length of 50 mm was brazed to the insulating heat-resistant ceramic layer portion of the thus obtained sintered body in the same manner as in Example 2 to obtain a solid. A joined body of the electrolyte and tungsten was obtained.

The airtightness of the bonded surface of the obtained bonded body was evaluated in the same manner as in Example 2. As a result, the airtightness of the bonded portion immediately after bonding was 1 × 10 ^{−9 which is} the detection limit of the He leak detector. Atm · cc / sec or less, 2
The detection limit of 1 × 10 ^-9 a even after holding at 70 ° C. for 4000 hours
tm · cc / sec or less, and airtightness was maintained.

Example 4 The length of the solid electrolyte was obtained without forming an insulating heat-resistant ceramic layer made of Al ₂ O ₃ having an outer diameter of 24 mmφ, an inner diameter of 18 mmφ and a length of 18 mm in the sintered body obtained in Example 2. Is 88 mm, except that it is 8 mm% Y ₂ O ₃ having an outer diameter of 24 mmφ, an inner diameter of 18 mmφ, and a length of 88 mm. 24m outer diameter at one end of solid electrolyte made of zirconia
A sintered body in which six mixed ceramic layers having mφ, an inner diameter of 18 mmφ, and a length of 2 mm were laminated was produced in the same manner as in Example 2.

A mixed ceramic layer at the end of the sintered body,
That is, Al ₂ O ₃ / stabilized zirconia (volume ratio) = 85
A Kovar alloy was brazed to the / 15 mixed ceramic layer in the same manner as in Example 2.

The airtightness of the bonded surface of the obtained bonded body was evaluated in the same manner as in Example 2. As a result, the airtightness of the bonded portion immediately after bonding was 1 × 10 ^{−9, which is} the detection limit of the He leak detector. Atm · cc / sec or less, 2
The detection limit of 1 × 10 ^-9 a even after holding at 70 ° C. for 4000 hours
tm · cc / sec or less, and airtightness was maintained.

In this method, a mixed ceramic layer of Al ₂ O ₃ / stabilized zirconia (volume ratio) = 85/15 functions as an insulating heat-resistant ceramic layer, and when the entire length of the ceramic portion is fixed. Has an effect that the portion of the solid electrolyte can be lengthened, and the function as the solid electrolyte increases.

Example 5 A sintered body having a structure in which six mixed ceramic layers were laminated on one end of the solid electrolyte and an insulating heat-resistant ceramic layer made of Al ₂ O ₃ was further laminated on one end of the solid electrolyte in the same manner as in Example 2. I got In this way, two sintered bodies having the same structure were produced, and the insulating heat-resistant ceramic layers of each sintered body were used in the same manner as in Example 2 using the same brazing material used in Example 2. Brazed under the following conditions.

With respect to the joined body obtained by joining the solid electrolytes thus obtained, the airtightness of the joined surface was evaluated in the same manner as in Example 2. As a result, the airtightness of the joined portion immediately after the joining was determined to be He leak. 1 × 10 ^-9 of detection limit of detector
atm · cc / sec or less, and 4
Even after holding for 000 hours, the detection limit is 1 × 10 ^-9 atm · cc
/ Sec or less, and airtightness was maintained.

Comparative Example 1 In the same manner as in Example 2, stabilized zirconia raw material powder containing 8 mol% Y ₂ O ₃ (composition: 85.7% by weight of ZrO ₂ ,
13.7% by weight of Y ₂ O _3, 0.5% by weight of Al ₂ O ₃ and 0.1% by weight of SiO ₂ ) were wet-pulverized to give an average particle size of 0.7.
A slurry of 3 μm was added, and 3% by weight of a wax emulsion was added as a molding aid, and the mixture was sized with a spray dryer to obtain granules having a particle size of 30 to 150 μm.

After the granules for molding thus obtained were filled in a rubber mold, they were cold molded at a hydrostatic pressure of 1000 kgf / cm ² , and calcined at 1600 ° C. for 3 hours in the atmosphere to give 8 mol%.
24 mm outer diameter made of stabilized zirconia containing Y ₂ O ₃
A cylindrical sintered body of a solid electrolyte having a diameter φ of 18 mmφ and a length of 100 mm was produced.

A Kovar alloy was brazed to this solid electrolyte in the same manner as in Example 2, and the airtightness of the joint was evaluated in the same manner as in Example 2. 1 × 1 of the detection limit of the He leak detector
0 ^-9 atm · cc / sec showed the following, 270 ℃,
After holding for 500 hours, the joint was in a state of being peeled by hand, and did not exhibit airtightness.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a state in which a YSZ-Al ₂ O ₃ gradient composition material and a metal are brazed in Example 1.

FIG. 2 is an explanatory diagram of a detailed composition distribution of a YSZ-Al ₂ O ₃ gradient composition material in Example 1.

FIG. 3 is a characteristic diagram showing a change in bonding strength after the bonded body obtained in Example 1 and a bonded body bonded by a conventional method are heated at 400 ° C. for a long time in the atmosphere.

FIG. 4 is a side view of a sintered body comprising a solid electrolyte, a mixed ceramics layer, and an insulating heat-resistant ceramics layer obtained in Example 2.

[Explanation of symbols]

1 ... made of YSZ solid electrolyte, 2 ... Al ₂ O ₃ made of insulating refractory _{ceramic, 3 ... YSZ-Al 2 O} 3 mixed _{ceramics, 4 ... YSZ-Al 2 O} 3 gradient composition material, 5 ... metal,
6 ... brazing material, 7 ... 12.5 vol% Al ₂ O ₃ /87.5 vol% YSZ
Mixed ceramics, 8 ... 25 vol% Al ₂ O _3/75 vol% YSZ mixed ceramics, 9 ... 37.5 vol% Al ₂ O ₃ /62.5 vol% YSZ of
Mixed ceramics, 10 ... 50 vol% Al ₂ O _3/50 vol% YSZ mixed ceramics, 11 ... 65 vol% Al ₂ O _3/35 vol% YSZ mixed ceramics, 12 ... 80 vol% Al ₂ O ₃ / 20 vol% YSZ mixed ceramics, 13 ... 90 vol% Al ₂ O _3/10 vol% YSZ mixed ceramics, 14 ... solid electrolyte, 15 ... mixing ceramic layer, 16: insulating heat resistant ceramic layer.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shozo Hirai 2-1-1 Shinhama, Arai-machi, Takasago-shi, Hyogo Mitsubishi Heavy Industries, Ltd. Inside Takasago Research Laboratory (72) Inventor Naoyuki Uejima 2-1-1, Arai-machi, Arai-machi, Takasago-shi, Hyogo Prefecture No. 1 Inside the Takasago Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Hiromichi Hani 3-24 Inori Onocho, Sakai City, Osaka Prefecture Inside Nikkato Co., Ltd. (72) Inventor Masanori Nakaya Onari Ono, Sakai City, Osaka Prefecture 3-24, Town 3 Nikkato Co., Ltd. (72) Inventor Koji Onishi 3-2-24, Onzai Onocho, Sakai City, Osaka Prefecture Nikkato Co., Ltd. (72) Inventor Saburo Kose, Sakai City, Osaka Prefecture Nikkato, 3-2-24, Sato-ono-cho (72) Inventor Toshio Kawanami 3-24, Enri-Onocho, Sakai-shi, Osaka Prefecture Nikkato, Inc. (56) Document JP-flat 2-188476 (JP, A) JP flat 4-2401 (JP, A) (58 ) investigated the field (Int.Cl. ^7, DB name) C04B 37/00 - 37/02 B23K 1 / 19

Claims (7)

(57) [Claims] When joining an object to be joined to a solid electrolyte made of a ceramic material, a mixed ceramic layer obtained by mixing the solid electrolyte material and the insulating heat-resistant ceramic material is joined to a joint of the solid electrolyte. after forming the insulating heat-resistant ceramic layer through, the insulating heat-resistant ceramic layer a bonding method of a solid electrolyte consisting of Rousset La mix material to heat-bonding the object to be joined, the junction of the solid electrolyte
Insulating heat-resistant ceramic layer via mixed ceramic layer
The method of forming the raw material fine powder constituting the solid electrolyte and
Regarding the raw material powder that constitutes the insulating heat-resistant ceramic,
The particle size of the powder and the particle size of the granules for molding are almost the same.
Is a method of pulverizing, sizing, laminating and firing.
A method for joining a solid electrolyte made of Lamix material. 2. The bonding method according to claim 1, wherein the solid electrolyte is zirconia having oxygen ion conductivity. 3. The bonding method according to claim 1, wherein the solid electrolyte is stabilized zirconia containing at least one of CaO, Y ₂ O ₃ and a rare earth oxide as a stabilizer. 4. An insulating heat-resistant ceramic comprising Al ₂ O ₃ ,
MgO, SiO ₂ , ZrO ₂ , MgO · Al ₂ O ₃ , M
gO.SiO ₂ , 2MgO.SiO ₂ , and ZrO _2.
The bonding method according to any one of claims 1 to 3 at least one oxide selected from SiO ₂ are those containing more than 60 vol%. 5. When the mixed ceramics layer is composed of 1 to 20 layers, and the mixed ceramics layer has a multilayer structure of two or more layers, the portion of the mixed ceramics layer closer to the insulating heat-resistant ceramics layer is more insulated. The bonding method according to any one of claims 1 to 4, wherein the content of the raw material for the heat-resistant ceramics is large, and the mixed ceramic layer closer to the solid electrolyte has a structure in which the content of the raw material for the solid electrolyte is larger. 6. The solid electrolyte is a ceramic containing ZrO ₂ as a main component, and the insulating heat-resistant ceramic is Al ₂ O _3.
A gradient composition of ZrO ₂ —Al ₂ O ₃ in which the mixed ceramic layer gradually increases in Al ₂ O ₃ concentration as the ZrO ₂ concentration gradually decreases from the solid electrolyte side to the insulating heat-resistant ceramic side. The bonding method according to any one of claims 1 to 5, wherein the ceramic is a sintered ceramic, and the solid electrolyte, the mixed ceramics layer, and the insulating heat-resistant ceramics layer are integrally sintered and manufactured. 7. The method according to claim 1, wherein the object to be joined is a metal material, an insulating heat-resistant ceramic, or a solid electrolyte having an insulating heat-resistant ceramic layer formed via a mixed ceramic layer. Joining method.