JP2006512275A - Glass ceramic material and manufacturing method thereof - Google Patents

Abstract

The present invention is a glass-ceramic material useful for joining a solid ceramic part and at least one other solid part, and a method for producing the same. This material is formulated with M1-M2-M3-M4, M1 is BaO, SrO, CaO, MgO, or combinations thereof, M2 is Al ₂ O ₃ and ₂ in the formulation. Present in an amount of ˜15 mol%, M3 is SiO ₂ with 50 mol% or less of B ₂ O ₃ and consists of La ₂ O ₃ , Y ₂ O ₃ , Nd ₂ O ₃ , or combinations thereof metal oxide selected from the group, or 0.1 to 7.5 mol% of K ₂ O. In the case of metal oxides from the group of La ₂ O ₃ , Y ₂ O ₃ , Nd ₂ O ₃ or combinations thereof, the composition preferably further contains 0.1 to 3 mol% CuO. In all cases, the glass-ceramic material in the crystalline phase substantially matches the thermal expansion coefficient of the solid electrolyte with a thermal expansion coefficient of 12 × 10 ⁻⁶ ° C. ⁻¹ when measured at 25 ° C. to 1000 ° C. This thermal expansion coefficient does not decrease even when the thermal cycle is repeated. In accordance with the present invention, a series of glass ceramics based on M1-Al ₂ O ₃ -M3-M4 can be applied to both cylindrical and planar solid oxide fuel cells, oxygen electrolyzers, and syngas, general chemicals and other It can be used in joining or sealing membrane reactors for manufacturing products.

Description

  This invention was completed with government support under the contract DE-AC0676RL01830 by the US Department of Energy. The government has certain rights to the invention.

  This application is a continuation-in-part of US patent application Ser. No. 09 / 562,583 (filed May 1, 2000). US patent application Ser. No. 09 / 562,583 is also a continuation-in-part of US patent application Ser. No. 09 / 365,343 (filed Jul. 30, 1999), now US Pat. No. 6,430,966.

FIELD OF THE INVENTION The present invention relates to glass ceramic materials and methods for their production, and more particularly to use in electrochemical devices such as fuel cells, gas sensors, oxygen or hydrogen pumps / separators, or seal materials having a coefficient of thermal expansion ( A glass-ceramic material and its manufacturing method for sealing any material close to sealing material).

  As used herein, the terms “solid electrolyte” or “solid oxide ion conducting electrolyte” are interchangeable.

  As used herein, the term “connecting member” includes the term “seal”. This is because in this glass-ceramic field, a “seal” connects at least two parts. However, the “connecting member” may be intermittent, and in this case, it does not serve as a “seal”.

Background of the Invention Ceramic materials are used extensively in everything from automotive turbochargers to experimental fuel cells. However, there remains the problem of connecting and / or sealing ceramic parts to other ceramic parts, metal parts, or combinations thereof (eg, cermet parts) so that the connecting member remains integral during operation. . For example, solid oxide ion conducting electrolytes are useful for oxygen separation and high temperature fuel cells. Although many technical challenges have been overcome in the development of these materials, the problem of sealing remains. In the case of a planar design, it is necessary to connect the parts together by an airtight seal to prevent the gas species on both sides of the solid oxide ion conducting electrolyte from mixing together.

There are limited materials suitable as solid oxide ion conducting electrolytes. The most commonly used materials are yttria stabilized zirconia (YSZ), doped ceria, doped bismuth oxide, and doped lanthanum gallate. is there. The coefficient of thermal expansion (TEC) of these materials can range from 10.1 × 10 ^{−6 to} 14.3 × 10 ⁻⁶ ° C. ⁻¹ depending on the type and concentration of the dopant. Of particular importance are materials whose TEC is greater than or equal to 12 × 10 ⁻⁶ ° C. ⁻¹ . The operating temperature can also range from 700 ° C. to 1000 ° C., depending on which material is selected for the electrolyte. Therefore, the sealing material must be adjusted to match the thermal expansion of the electrolyte, maintain a hermetic seal at temperatures in the range of 200 ° C. to 1200 ° C., and avoid harmful interchemical reactions with various fuel cell components. . The sealing material must also be stable and electrically insulating at operating temperatures (800-1000 ° C.) for extended periods (> 9,000 hr). For solid oxide fuel cells, the seal must be able to withstand an extremely reducing environment.

  Various attempts have been made to seal solid oxide ion conducting devices, and the degree of success of these attempts varies. Silica, boron, phosphate glass and glass ceramic have been evaluated as sealing materials for solid oxide fuel cells (1-4). Experiments conducted by P.H. Larsen et al. (1) have shown that there are significant problems with glasses based solely on phosphate as the glass former. The phosphate volatilized at a certain temperature and reacted with the anode to form nickel phosphide and zirconium oxyphosphate. Also, such phosphate glasses often crystallized to yield metaphosphoric acid or pyrophosphoric acid, which showed low stability in humidified fuel gases at operating temperatures.

Borosilicate glass and glass ceramic have also been considered as potential sealing materials. For the use in solid oxide fuel cells of these glasses, C. Studied by Gunther et al ² and KL Ley et al ³ is performed. However, at operating temperatures, boron reacts with a humidified hydrogen atmosphere and forms B ₂ (OH) ₂ and B ₂ (OH) ₃ gas species ² . Accordingly, all boron seals corrode over time in a humidified hydrogen environment. Glass composed of B ₂ O ₃ as a glass former exhibits a weight loss of less than 20% in a humidified hydrogen environment and has extensive interaction with fuel cell component materials both in air and in wet fuel gas Produced ¹ .

Most promising are silica glass and glass ceramic. These materials are usually highly chemical resistant and show minimal interaction with fuel cell component materials ¹ . Unfortunately, these glasses tend to exhibit thermal expansion that is less than that required for sealing materials.

  At operating temperatures, most glasses crystallize over time. Therefore, it is essential to have a glass composition whose thermal expansion coefficient after crystallization is compatible with the solid oxide ion conductive electrolyte. Once glass is completely crystallized, it is usually very stable over time. In addition, crystallized glass tends to be mechanically stronger at operating temperatures and improves sealing performance.

  Yet another problem faced by those skilled in the art is that glass TEC tends to decrease over time.

Thus, the art has a TEC of 12 x 10 ^-6 ° C ^-1 or higher in the crystalline phase that can operate at operating temperatures of about 900 ° C or less, does not decrease over time, and has components and harmful chemicals What is needed is a seal material that does not cause interaction.

Background literature

SUMMARY OF THE INVENTION The present invention relates to glass ceramic compounds useful in joining or sealing ceramic parts to other ceramic parts, glass parts, metal parts, or combinations thereof (eg, cermet parts), and methods of making the same. More particularly, the present invention comprises an electrochemical cell connection comprising at least one solid electrolyte, the first side and the second side of which are exposed to a first gas species and a second gas species, respectively. / Useful for sealing. This seal is required to separate the first and second gas species.

This glass ceramic compound contains at least four metal oxides, M1-M2-M3-M4. M1 is BaO, SrO, CaO, MgO, or a combination thereof. M2 is Al ₂ O _3, and present in an amount of 2 to 15 mol% in the compound. M3 is SiO ₂ having 50 mol% or less of B ₂ O ₃ . M4 is 0.1 to 7.5 between mol% _{of, La 2 O 3, Y 2} O 3, Nd 2 O 3, or metal oxide selected from the group consisting a combination thereof, or 0.1 to 7.5 mol% among the K Either ₂ O. In the case of a metal oxide selected from the group consisting of La ₂ O ₃ , Y ₂ O ₃ , Nd ₂ O ₃ or combinations thereof, the composition may be used as a wetting agent to assist in bonding of the glass as 0.1 to 3 It is preferable to further contain mol% CuO.

Solid ceramic component and a ceramic, metal, or at least one other solid component is either a combination thereof, the expansion coefficient of the crystal phase when measured at 25 ° C. to 1000 ° C.,, 12 or 12 x 10 ^{- When} selected as greater than ⁶ ° C. ⁻¹ , this compound has a substantially consistent thermal expansion coefficient with these parts.

In the present invention, a series of glass ceramics based on M1-Al ₂ O ₃ -M3-M4 can be used to connect or seal both cylindrical and planar ceramic solid oxide fuel cells, oxygen electrolyzers, Used as a protective coating on metal substrates used as a support for catalyst particles used in high temperature catalytic reactions, as a thermal barrier coating, or in high temperature superalloys (in this application, the metal part is coated with a ceramic material. It is desirable to improve its oxidation resistance), and it can be used in membrane reactors used when producing synthesis gas, general-purpose chemical products and other products.

  In high temperature superalloy applications, it is often necessary to coat metal parts with a ceramic material to improve oxidation resistance. For example, the aerospace industry uses thermal barrier coatings when coating turbine blades and other parts. Multi-layer coatings are typically used to address problems such as oxygen diffusion and thermal expansion mismatch. The present invention is very suitable for this application. High temperature catalysis also requires the use of a protective coating on the metal surface. A thin metal substrate is often used as a support for the catalyst particles, but at a high temperature and high pressure, the thin metal substrate is oxidized and collapses. When a protective oxide coating is applied to a thin metal foil, the service life of the metal substrate can be extended, and it can be manufactured cheaper and easier than the entire ceramic part. At that time, the surface of these oxides becomes a substrate for holding the catalyst particles. The present invention is very suitable for use in such a manner.

  The present invention is also well suited for sealing glass material surfaces such as those used in the lighting industry. High performance, special purpose light bulbs require glass to metal seals to provide a connection between the filament and the glass bulb. Some of the gases in these bulbs are highly corrosive, and the bulbs are very hot, causing the problem of thermal expansion mismatch between the electrical contacts of the filament and the glass wall. Causes a general bad site. The present invention is very suitable for solving this problem.

The application of the present invention using a metal oxide selected from the group consisting of La ₂ O ₃ , Y ₂ O ₃ , Nd ₂ O ₃ , or combinations thereof is the use of solid oxide fuel cells where electrical resistance is desired The application of the present invention using K ₂ O is particularly suitable for applications such as oxygen sensors where electrical resistance is not a top priority.

  An object of the present invention is to provide a compound useful in joining or sealing a solid electrolyte or a solid oxide ion conductive electrolyte.

The advantage of the connecting member / seal produced using the M1-Al ₂ O ₃ -M3-M4 compound is that a substantially constant thermal expansion coefficient is maintained from the glass phase to the crystalline phase.

  The subject matter of the present invention is pointed out in detail in the concluding portion of the specification and is clearly stated in the claims. However, both the configuration and method of operation of the present invention, together with their further advantages and purposes, can best be understood by reference to the following description.

DESCRIPTION OF PREFERRED EMBODIMENTS The present invention is a glass ceramic compound and a method for producing the glass ceramic compound. The present invention relates to the joining or sealing of at least two solid ceramic components (for example, the first side and the second side of at least one solid electrolyte are exposed to the first and second gas species, respectively). Useful as a seal for electrochemical cells). The present invention is also useful when joining or sealing solid ceramic parts and metal parts or cermet parts. Seals are necessary to keep the first and second gas species separated during operation, usually performed at high temperatures.

The present invention includes a connection member between a solid ceramic component and at least one other solid component, preferably a combination thereof, such as a solid ceramic component, a metal component, or a cermet component. This connecting member has at least four metal oxides M1-M2-M3-M4. M1 is BaO, SrO, CaO, MgO, or a combination thereof. M2 is Al ₂ O ₃ . M3 is SiO ₂ having 50 mol% or less of B ₂ O ₃ . M4 is a 0.1 to 7.5 mol%, or a _{La 2 O 3, Y 2 O} 3, Nd 2 O 3 or a metal oxide selected from the group consisting a combination thereof,, 0.1 to 7.5 mol% of K It is either ₂ O. When the metal oxide is selected from the group consisting of La ₂ O ₃ , Y ₂ O ₃ , Nd ₂ O ₃ , or combinations thereof, the composition further contains 0.1-3 mol% CuO (This has been shown to provide wettability, thus assisting the binding while improving, or at least not reducing, TEC degradation over time). The connecting member substantially matches the thermal expansion coefficient of each component including the connecting member. The thermal expansion coefficient of the connecting member is 12 × 10 ⁻⁶ ° C. ⁻¹ or more when measured at 25 ° C. to 1000 ° C.

The composition of the connecting member / seal, M1 is present in an amount of about 20 mol% ~ about 55 mol%, Al ₂ O ₃ is present in an amount of about 2 mol% ~ about 15 mol%, M3 is approximately 40 It is preferred that the range be present in an amount from mol% to about 70 mol%. M4 is 0.1 to 7.5 mol% of _{La 2 O 3, Y 2 O} 3, Nd 2 O 3 or or a metal oxide selected from the group consisting a combination thereof, or 0.1 to 7.5 mol% of K _2, O. When it is a metal oxide from the group of La ₂ O ₃ , Y ₂ O ₃ , Nd ₂ O ₃ , or combinations thereof, the composition is 0.1-3 mol to improve the wettability of the composition It is preferable to further contain% CuO.

  As used herein, “substantially the same coefficient of thermal expansion” means within about 30%, preferably within about 16%, more preferably within about 5% of the thermal expansion coefficient of the material being sealed. Defined as coefficient of thermal expansion.

The connecting member is a test electrochemical cell and can be used when the oxygen ion pump and the test material are joined. Connection members are also used in oxygen generators or fuel cells to join oxygen ion conducting electrolytes, such as zirconia electrolytes, and interconnect materials, such as manganite, chromite, metals, and combinations thereof. May be. With regard to those aspects of the present invention that utilize metal oxides from the group of La ₂ O ₃ , Y ₂ O ₃ , Nd ₂ O ₃ or combinations thereof, preferred applications include electricity such as solid oxide fuel cells. There are applications where resistance is desired. With respect to those aspects of the present invention that utilize K ₂ O, preferred applications include applications where electrical resistance is not essential, such as oxygen generators.

  Experiments were conducted to demonstrate the glass ceramic material of the present invention. Glasses having the compositions shown in Table 1 were produced.

Thereafter, the glasses in Table 1 were tested to determine the coefficient of thermal expansion before and after crystallization and before and after repeating the thermal cycle. The results are shown in Table 2 below. (TEC x ^10-6 ° C- ¹ was measured from 25 ° C to 1000 ° C).

As shown in Table 2, all glasses met the criteria that the TEC measured at 25 ° C. to 1000 ° C. was 12 × 10 ⁻⁶ ° C. ⁻¹ or higher. Each glass was then tested and after repeated thermal cycles, it was determined if the TEC after crystallization decreased. In each case, the TEC of the glass of the example was determined to withstand repeated thermal cycles and remain above 12 × 10 ⁻⁶ ° C. ⁻¹ when measured at 25 ° C. to 1000 ° C.

CONCLUSION While preferred embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that many changes and modifications can be made without departing from the invention in its broader aspects. . Accordingly, the appended claims are intended to cover all such changes and modifications as fall within the true spirit and scope of this invention.

Claims (16)

A connecting member between a solid ceramic part and at least one other solid part,
The connecting member includes at least four metal oxides of M1-M2-M3-M4 combined together, M1 is selected from the group from BaO, SrO, CaO, MgO, and combinations thereof, and M2 is Al. a ₂ O _3, M2 is present in an amount of 2~15mol%, M3 is a SiO ₂ having a 50 mol% or less of B ₂ O _3, M4 is a K ₂ O, M4 0.1 A connecting member that is present in an amount of ˜7.5 mol%, wherein the connecting member substantially matches the coefficient of thermal expansion of the solid ceramic component and the at least one other solid component.   The connecting member according to claim 1, wherein the at least one other solid component is ceramic.   The connecting member according to claim 1, wherein the at least one other solid component is a metal.   2. The connection member according to claim 1, wherein the at least one other solid part is a cermet.   The connecting member according to claim 1, wherein the at least one other solid component is glass.   2. The connection member according to claim 1, wherein the connection member is a seal. 2. The connection member according to claim 1, wherein the coefficient of thermal expansion after crystallization is greater than 12 × 10 ⁻⁶ ° C. ⁻¹ when measured at 25 ° C. to 1000 ° C. A connecting member between the solid ceramic component and at least one other solid component, the connecting member comprising at least five metal oxides of M1-M2-M3-M4-M5 combined together, M1 but, BaO, SrO, CaO, MgO , and is selected from the group consisting of, M2 is an Al ₂ O _3, M2 is present in an amount of 2~15mol%, M3 is, 50 mol% or less SiO ₂ having B ₂ O ₃ and M4 is a metal oxide selected from the group consisting of La ₂ O ₃ , Y ₂ O ₃ , Nd ₂ O ₃ , or combinations thereof, and M5 is 0.1 And 3 mol% CuO, the connecting member being substantially compatible with the coefficient of thermal expansion of the solid ceramic component and the at least one other solid component.   9. The connection member according to claim 8, wherein the at least one other solid part is ceramic.   9. The connection member according to claim 8, wherein the at least one other solid part is a metal.   9. The connection member according to claim 8, wherein the at least one other solid part is a cermet.   9. The connecting member according to claim 8, wherein at least one other solid part is glass.   9. The connection member according to claim 8, which is a seal. 9. The connection member according to claim 8, wherein a coefficient of thermal expansion after crystallization is greater than 12 × 10 ⁻⁶ ° C. ⁻¹ when measured at 25 ° C. to 1000 ° C.   9. The method of claim 8, wherein the solid ceramic component and the at least one other solid component are an oxygen ion conductor and an interconnect in a solid oxide fuel cell.   9. The connecting member according to claim 8, wherein the solid ceramic component and at least one other solid component are an oxygen ion conductor and an interconnect material in the oxygen generator.