WO2015173429A1

WO2015173429A1 - Method for providing a glass joint between a ceramic component and a substrate, joining composition and glass joint

Info

Publication number: WO2015173429A1
Application number: PCT/EP2015/060871
Authority: WO
Inventors: Marijke Jacobs
Original assignee: Vito Nv
Priority date: 2014-05-16
Filing date: 2015-05-18
Publication date: 2015-11-19

Abstract

The invention relates to a composition comprising: (a) 22 –55 wt.% SiO₂, (b) 2 –1 wt.% MO wherein M is Mg or Zn, (c) 15 –48 wt.% BaO, (d) 2 –30 wt.% Bi₂O₃, and (e) 0.5 –25 wt.% ceramic-based material and optionally, a liquid medium; wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight of the composition excluding any liquid medium. The invention also relates to a method for providing a joint or a seal between a ceramic component and a substrate, wherein the method comprises the steps of: (i) providing a joining/sealing composition according to the invention, (ii) contacting the composition with the ceramic component and the substrate; and (iii) heating the composition to a sufficiently high temperature for said joint or seal between the ceramic component and the substrate to be formed. The invention further relates to a joint or a seal between a ceramic component and a substrate, said joint or seal comprising the joining/sealing composition according to the invention, to the use of the composition and joint according to the invention and to a device comprising a joint or a seal according to the invention.

Description

Method for providing a glass joint between a ceramic component and a substrate, joining composition and glass joint

Technical field of the invention

The present invention relates to a glass joint, in particular to a glass joint between a ceramic component and a substrate. The invention also relates to a joining composition, and to a method for providing a joint between a ceramic component and a substrate. In a specific embodiment, the invention relates to a glass seal between a ceramic component and a substrate, a sealing composition and a method for providing a glass seal between a ceramic component and a substrate.

Background of the invention

There are several applications wherein it is important to provide a joint, in particular a gastight joint, i.e. a seal, between a ceramic material and another ceramic material, or between a ceramic material and e.g. a metal or metal alloy. Examples where the providing of such a joint or seal is important include catalytic membrane reactors (CMR) and solid oxide fuel cells (SOFC).

A particular application is the provision of a gastight seal at high temperatures for dense mixed ionic electronic conducting (MIEC) ceramic membranes. MIEC membranes are interesting for high temperature gas separation and membrane reactor processes, and this type of membrane is used for e.g. oxy-combustion or in catalytic membrane reactors, e.g. for the oxidative coupling of methane (OCM). The operating temperature of these membranes is typically between 750 and 1000°C. Practical applications and experimental studies of these membranes require a seal between a membrane and a dense ceramic or metal tube or flat plate.

In general, a seal for a high temperature application of a ceramic membrane should meet the following requirements: the "melted" seal should have good wettability with both the membrane and the supporting structure, the seal material should have suitable viscosity and rigidity in the operating temperature range, the seal should be chemically inert at the operating temperature range, and the thermal expansion coefficient of the seal should be compatible with the membrane and the supporting structure in order to avoid thermal expansion mismatch leading to sealing failure caused by a temperature change.

Several seals between a ceramic component and another material are known in the art. WO 01/09059, incorporated by reference herein, discloses a glass-ceramic joining material and a method of joining a solid ceramic component and at least one other solid component. The glass-ceramic compound comprises at least three metal oxides, Ml -M - MS. Ml is BaO, SrO, CaO, MgO or combinations thereof, and is present in an amount from about 20 mol% to about 55 mol%. M2 is AI₂O₃ and is present in the compound in an amount of from 2 to 15 mol%. M3 is Si0₂ with up to 50 mol% B₂0₃, and is present in an amount from about 40 mol% to about 70 mol%. The sealing material has a coefficient of thermal expansion between 8 x 10^"6 and 15 x 10^"6 °C^_1.

US 7007509, incorporated by reference herein, discloses a glass matrix composition widely defined as consisting essentially of about 55 - 75 mol% Si0₂, 5 - 30 mol% BaO and 2 - 22 mol% MgO, for use as a matrix of composite materials. In addition, a method of making a glass matrix-ceramic particulate composite for sealing electrochemical structures is disclosed, said composite comprising a physical admixture of finely divided ceramic (e.g. Mg₂Si0₄) particulates to the glass matrix composition disclosed above, to reach an overall composition of 55 - 65 mol% Si0₂, 5 - 15 BaO and 25 - 35 MgO. This document thus does not envisage making composite materials having a higher BaO composition, let alone composite materials comprising Bi₂0₃.

US 6402156, incorporated by reference herein, discloses glass-ceramic sealants and methods of making seals between a ceramic material and substrate which may be another ceramic, metal or a metal alloy. Generally, the sealant materials have a coefficient of thermal expansion ranging from about 1 x 10^"6 to about 25 x 10^"6 °C^_1. The sealant composition comprises about 40% to about 85% Si0₂ by weight, and three or more metal oxides selected from the group of aluminum oxide, cobalt oxide, sodium oxide, boron oxide, calcium oxide, magnesium oxide, zinc oxide, titanium oxide, lithium oxide, potassium oxide, phosphorous oxide and zirconium oxide, combined with 0.5% to about 80% by weight of a mixed metal oxide ceramic membrane material.

X. Qi et ah, Journal of Membrane Sciences 2001, 193, 185 - 193, incorporated by reference herein, discloses ceramic-glass composite high temperature seals for dense ionic-conducting ceramic membranes. Typically, the ceramic-glass composite seal is composed of 40 - 50 wt.% membrane material powder, 20 - 50 wt.% Pyrex glass and 5 - 20 wt.%) additive such as sodium aluminate and boron oxide. Pyrex 7740 glass, composed of 80.6 wt.% S1O2, 13 wt.% B₂0₃, 4 wt.% Na₂0, 2.3 wt.% A1₂0₃ and 0.1 wt.% K₂0, is used. C. Lara et al., Journal of Non-Crystalline Solids 2004, 348, 149, incorporated by reference herein, discloses glass-ceramic materials comprising RO-BaO-Si0₂ (R = Mg, Zn), having good thermal properties for sealing materials on planar-type solid oxide fuel cells (SOFC) at high and intermediate temperatures. The glass compositions comprise from 30 to 70 mol% Si0₂ and BaO/RO (R = Mg or Zn) in a ratio of 4, 1.5, 0.67 or 0.25.

In A. Goel et al., International Journal of Hydrogen Energy 2010, 35, 6911, incorporated by reference herein, glass-ceramic sealants for solid oxide fuel cells comprising MgO, CaO, SrO, Si0₂, A1₂0₃, La₂0₃, B₂0₃ and NiO, doped with 1 to 5 wt.% of Bi₂0₃ are disclosed. The dilatomeric glass transition temperature (T_g) decreased with increasing Bi₂0₃ content in the glasses, while no significant impact of Bi₂0₃ concentration on softening temperature (T_s) of the glasses was observed. In general, addition of Bi₂0₃ improved the sintering ability of the glass compositions. No significant effect on the microstructure of the sintered glass-ceramics was observed, although the crystalline phase assemblages was changed. No significant differences were observed in the chemical interaction between glass-ceramics sealants and metallic interconnects due to the addition of Bi₂0₃.

M.J. Pascual et al, Journal of Power Sources 2007, 169, 40 - 46, incorporated by reference herein, discloses various glass compositions for solid oxide fuel cells (SOFC), comprising 35, 40, 45, 50 or 55 mol% Si0₂, 27 mol% BaO, 10 or 18 mol% MgO, 0, 5, 10, 15 or 20 mol% B₂0₃, 0 or 10 mol% PbO and 0 or 8 mol% ZnO. The union and chemical compatibility of these compositions were tested on Crofer 22.

A disadvantage of glass joints and glass seals known in the art is that the properties of the joint or seal are not always favourable. For example, at high temperature the joints or seals may react with the materials they are connecting and/or the seals may not be gastight or may not remain gastight over a prolonged period of time. In addition, when the joint is a seal between a ceramic membrane and another component, the material of the seal may diffuse into the membrane, resulting in a decrease of the flux through the membrane.

Summary of the invention

The present invention relates to a method for providing a joint between component and a substrate, wherein the method comprises the steps of:

(i) providing a composition comprising: (a) 22 - 55 wt.% Si0₂,

(b) 2 - 15 wt.% MO wherein M is Mg or Zn,

(c) 15 - 48 wt.% BaO,

(d) 2 - 30 wt.% Bi₂0₃,

(e) 0.5 - 25 wt.%) ceramic-based material other than (a), (b), (c), and (d), and

(f) optionally, a liquid medium in order to form a paste of said composition;

wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight of the composition excluding any liquid medium;

(ii) contacting the composition with the ceramic component and the substrate; and

(iii) heating the composition to a sufficiently high temperature for a joint between the ceramic component and the substrate to be formed.

In a particular embodiment of the method according to the invention, the joint between a ceramic component and a substrate is a seal.

In further particular embodiments, said composition comprises

(a) 32 - 48 wt.% Si0₂;

(b) 4 - 10 wt.% MO wherein M is Mg or Zn;

(c) 20 - 30 wt.% BaO;

(d) 10 - 23 wt.% Bi₂0₃; and

(e) 3 - 18 wt.% ceramic-based material,

wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight of the composition excluding any liquid medium.

More particularly, the composition comprises less than 0.5 wt.% B₂0₃.

The invention further relates to a composition comprising:

(a) 22 - 55 wt.% Si0₂,

(b) 2 - 15 wt.% MO wherein M is Mg or Zn,

(c) 15 - 48 wt.% BaO,

(d) 2 - 30 wt.% Bi₂0₃,

(e) 0.5 - 25 wt.%) ceramic-based material other than (a), (b), (c), and (d), and (f) Optionally, a liquid medium in order to form a paste of said composition; wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight of the composition, excluding any liquid medium.

The invention further relates to the use of the composition according to the invention in a method for providing a joint or a seal between a ceramic component and a substrate.

The invention further relates to glass seal compositions which are particularly suitable for the generation of the compositions provided herein.

In addition, the invention relates to a joint between a ceramic component and a substrate, wherein the joint comprises a composition according to the invention, to the use of the compositions envisaged herein and to a device, comprising a joint according to the invention. More particularly, the invention relates to a ceramic component and a substrate which are joined via a joint, wherein the joint comprises a composition as described herein. The invention further relates to a device comprising such ceramic component and substrate which are joined via said joint.

Detailed description of the invention

Definitions

The verb "to comprise" and its conjugations as used in this description and in the claims are used in their non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded.

In addition, reference to an element by the indefinite article "a" or "an" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there is one and only one of the elements. The indefinite article "a" or "an" thus usually means "at least one".

The term "joint" herein refers to a connection between two (or more) components, in particular to a connection between a ceramic component and an additional component. The term "joint" herein also refers to a connection between more than two components, wherein one (or more) of said components is a ceramic component. The term "joint" thus also refers to a connection between one (or more) ceramic components and two (or more) additional components, and to a connection between two (or more) ceramic components and one (or more) additional components. The one or more additional components are herein also referred to as "substrate" or "substrates". A joint herein thus refers to a connection between a ceramic component and a substrate. A joint herein also refers to a connection between one or more ceramic components and one or more substrates. Said ceramic component(s) and substrate(s) are bonded together by the joint.

A joint between two (or more) parts may be intermittent, i.e. discontinuous, and therefore a joint is not necessarily gastight. The term "joint" herein includes the term "seal". The term "seal" is herein defined as a joint, i.e. a connection between two (or more) components as defined above, wherein said joint is gastight. As defined herein, a seal is thus a specific embodiment of a joint. Joining/sealing composition

The inventors have found that compositions comprising a glass matrix combined with B1₂O₃ and a ceramic-based material, more specifically, where these components are combined in specific ratios, provides particular advantages for use in specific applications such as the provision of good joints and seals. More particularly, the compositions characterized by comprising 2 - 30 wt.% B1₂O₃, such as 6 - 30 wt. %, 10 - 30 wt.% or more particularly 15-20 wt.% B1₂O₃, are characterized by particularly suitable thermal, chemical and mechanical properties. Most particularly it has been found that they have improved wettability, chemical inertness and thermal resistance. In a first aspect, the present invention relates to a composition comprising:

(a) 22 - 55 wt.% Si0₂,

(b) 2 - 15 wt.% MO wherein M is Mg or Zn,

(c) 15 - 48 wt.% BaO,

(d) 2 - 30 wt.% Bi₂0₃, and

(e) 0.5 - 25 wt.% ceramic-based material, and

(f) optionally, a liquid medium

wherein the concentrations in wt.% based on the total weight of the composition excluding any liquid medium (if present).

In particular embodiments, components (a), (b), (c), and (d) may be present in the composition as a glass material, or as ceramic material. The ceramic-based material of component (e) typically is different from any of the materials (a)-(d).

As will be clear to a person skilled in the art, the sum of the amounts of all components present in said composition is 100 wt.%>. The composition according to the invention may comprise additional components. The invention thus further relates to a composition comprising (a) 22 - 55 wt.% Si0₂, (b) 2 - 15 wt.% MO wherein M is Mg or Zn, (c) 15 - 48 wt.% BaO, (d) 2 - 30 wt.% Bi₂0₃, and (e) 0.5 - 25 wt.% ceramic-based material, all based on the total weight of the composition (excluding any liquid medium), wherein the sum of the amounts of (a), (b), (c), (d), (e) and any additional component present in said composition, is equal to 100 wt.%.

The compositions described herein can provide good joints and seals without requiring the presence of common glass components such as alkali oxides or boron trioxide (B₂0₃) in the composition. In particular for sealing ceramic materials, such components can lead to significant mismatch in the coefficients of thermal expansion (CTE) of the seal and the materials to be sealed. Moreover, alkali oxides can cause unwanted reactions with material to be sealed. In particular embodiments, the composition described herein comprises less than 1 wt.% B₂0₃, preferably less than 0.5 wt.% B₂0₃. In certain embodiments, the composition comprises less than 0.1 wt.%. In certain embodiments, the composition does not comprise B₂0₃.

In particular embodiments, the total concentration of alkali oxides in the composition is below 0.5 wt.%, preferably below 0.1 wt.%. In certain embodiments, the composition does not comprise alkali oxides. The term "alkali oxide" as used herein refers to an oxide selected from lithium oxide (Li₂0), sodium oxide (Na₂0), potassium oxide (K₂0), rubidium oxide (Rb₂0), and cesium oxide (Cs₂0).

In particular embodiments, the total concentration of alkali oxides and B₂0₃ in the composition is below 1.0 wt.%, preferably below 0.2 wt.%, or below 0.1 wt.%. In certain embodiments, the composition does not comprise an alkali oxide or B₂0₃.

In a particular embodiment of the composition according to the invention, the composition consists essentially of (a) 22 - 55 wt.% Si0₂, (b) 2 - 15 wt.% MO wherein M is Mg or Zn, (c) 15 - 48 wt.% BaO, (d) 2 - 30 wt.% Bi₂0₃, (e) 0.5 - 25 wt.% ceramic- based material, and optionally a liquid medium, wherein said concentrations in wt.% are all based on the total weight of the composition excluding any liquid medium.

With the term "consists essentially of it is herein meant that said composition consists for about 95 wt.% or more, preferably for about 96 wt.% or more, more preferably for about 97 wt.% or more, even more preferably for about 98 wt.% or more, yet even more preferably for about 99 wt.% or more and most preferably for about 99.5 wt.% or more of the components (a), (b), (c), (d), (e), and (optionally) (f). In other words, although some minor additional components, e.g. impurities, may be present, said composition does not comprise an additional major component apart from (a), (b), (c), (d), (e), and (f).

In a preferred embodiment, the composition according to the invention comprises (a) 25 - 55 wt.% Si0₂, (b) 2 - 15 wt.% MO wherein M is Mg or Zn, (c) 15 - 40 wt.% BaO, (d) 2 - 30 wt.% Bi₂0₃, and (e) 2 - 25 wt.% ceramic-based material, all based on the total weight of the composition (excluding any liquid medium). In another preferred embodiment, the composition according to the invention consists essentially of (a) 25 - 55 wt.% Si0₂, (b) 2 - 15 wt.% MO wherein M is Mg or Zn, (c) 15 - 40 wt.% BaO, (d) 2

- 30 wt.% Bi₂0₃, and (e) 2 - 25 wt.% ceramic-based material, all based on the total weight of the composition.

In a particular embodiment, the composition according to the invention comprises

(a) 25 - 55 wt.% Si0₂, (b) 2 - 15 wt.% MO wherein M is Mg or Zn, (c) 15 - 40 wt.% BaO, (d) 6 - 30 wt.% Bi₂0₃, and (e) 2 - 25 wt.% ceramic-based material, all based on the total weight of the composition (excluding any liquid medium). In another preferred embodiment, the composition according to the invention consists essentially of (a) 25 - 55 wt.% Si0₂, (b) 2 - 15 wt.% MO wherein M is Mg or Zn, (c) 15 - 40 wt.% BaO, (d) 6

In a particular embodiment, the composition according to the invention comprises (a) 25 - 55 wt.% Si0₂, (b) 2 - 15 wt.% MO wherein M is Mg or Zn, (c) 15 - 40 wt.% BaO, (d) 10 - 30 wt.% Bi₂0₃, and (e) 2 - 25 wt.% ceramic-based material, all based on the total weight of the composition (excluding any liquid medium). In another preferred embodiment, the composition according to the invention consists essentially of (a) 25 - 55 wt.% Si0₂, (b) 2 - 15 wt.% MO wherein M is Mg or Zn, (c) 15 - 40 wt.% BaO, (d) 10

- 30 wt.% Bi₂0₃, and (e) 2 - 25 wt.% ceramic-based material, all based on the total weight of the composition

In a more preferred embodiment, the composition according to the invention comprises (a) 30 - 50 wt.% Si0₂, (b) 3 - 13 wt.% MO wherein M is Mg or Zn, (c) 18 - 35 wt.%) BaO, (d) 5 - 25 wt.% Bi₂0₃, and (e) 2 - 20 wt.% ceramic-based material, all based on the total weight of the composition (excluding any liquid medium). In another preferred embodiment, the composition according to the invention consists essentially of (a) 30 - 50 wt.% Si0₂, (b) 3 - 13 wt.% MO wherein M is Mg or Zn, (c) 18 - 35 wt.% BaO, (d) 5 - 25 wt.% Bi₂0₃, and (e) 2 - 20 wt.% ceramic-based material, all based on the total weight of the composition.

In an even more preferred embodiment, the composition according to the invention comprises (a) 32 - 48 wt.% Si0₂, (b) 4 - 10 wt.% MO wherein M is Mg or Zn, (c) 20 - 30 wt.% BaO, (d) 10 - 23 wt.% Bi₂0₃, and (e) 3 - 18 wt.% ceramic-based material, all based on the total weight of the composition (excluding any liquid medium). In another more preferred embodiment, the composition according to the invention consists essentially of (a) 32 - 48 wt.% Si0₂, (b) 4 - 10 wt.% MO wherein M is Mg or Zn, (c) 20 - 30 wt.% BaO, (d) 10 - 23 wt.% Bi₂0₃, and (e) 3 - 18 wt.% ceramic-based material, all based on the total weight of the composition.

In an even more preferred embodiment, the composition according to the invention comprises (a) 35 - 45 wt.% Si0₂, (b) 5 - 8 wt.% MO wherein M is Mg or Zn, (c) 22 - 28 wt.%) BaO, (d) 13 - 20 wt.% Bi₂0₃, and (e) 4 - 15 wt.% ceramic-based material, all based on the total weight of the composition (excluding any liquid medium). In another even more preferred embodiment, the composition according to the invention consists essentially of (a) 35 - 45 wt.% Si0₂, (b) 5 - 8 wt.% MO wherein M is Mg or Zn, (c) 22 - 28 wt.% BaO, (d) 13 - 20 wt.% Bi₂0₃, and (e) 4 - 15 wt.% ceramic-based material, all based on the total weight of the composition.

Most preferably, the composition according to the invention comprises (a) 37 - 43 wt.% S1O2, (b) 6 - 7.5 wt.% MO wherein M is Mg or Zn, (c) 23 - 27 wt.% BaO, (d) 15 - 19 wt.% Bi₂0₃, and (e) 5 - 14 wt.% ceramic-based material, all based on the total weight of the composition (excluding any liquid medium). In another most preferred embodiment, the composition consists essentially of (a) 37 - 43 wt.% Si0₂, (b) 6 - 7.5 wt.% MO wherein M is Mg or Zn, (c) 23 - 27 wt.% BaO, (d) 15 - 19 wt.% Bi₂0₃, and (e) 5 - 14 wt.% ceramic-based material, all based on the total weight of the composition.

In particular embodiments, the sum of components (d) (i.e. Bi₂0₃) and (e) (i.e. ceramic-based material), i.e. components (d) and (e) together, forms at least 15 wt.%, more particularly at least 17 wt.% of the composition (excluding any liquid medium). The inventors have found that such compositions can provide particularly good seals. The composition according to the invention is very suitable for providing a joint between a ceramic component and a substrate, and for providing a seal between a ceramic component and a substrate (see below). The composition according to the invention may therefore also be referred to as a joining composition or a sealing composition, or, alternatively, as a joining/sealing composition.

Preferably, the composition according to the invention is a particulate composition, more preferably a powder. The particle size of said powder is preferably in the range of about 1 to about 50 μιη, more preferably of about 1.5 to about 45 μιη, even more preferably of about 2 to about 40 μιη, yet even more preferably of about 2.5 to about 35 μιη, and most preferably of about 3 to about 35 μιη. The present inventors have found that the use of such particles allows for obtaining a good thermal match with the material to be sealed, while providing a gas tight seal. The particle size of the powder may be measured via laser diffraction, more particularly according to ISO 13320:2009. For non- spherical particles, the size may refer to an equivalent diameter. Typically, the particle sizes mentioned herein refer to a number average. The span of the size distribution may be in the range of about 50 to about 0.1, preferably in the range of about 3 to about 0.1, in particular about 3 to about 1, or about 2 to about 1, and more preferably about 1.5 to about 1.7.

As described above, the composition according to the invention comprises MO, wherein M is Zn or Mg. In a preferred embodiment, M is Mg.

In a preferred embodiment of the joining/sealing composition according to the invention, (a), (b) and (c) are comprised in a glass matrix composition. The term "glass matrix composition" herein refers to a glass composition comprising Si0₂, MO wherein M is Mg or Zn (preferably Mg), and BaO. Preferably, the glass matrix composition is a particulate composition. In other words, preferably, (a), (b) and (c) are present in the form of a glass composition comprising the appropriate amount of Si0₂, MO wherein M is Mg or Zn (preferably Mg), and BaO.

As described above, the joining/sealing composition according to the invention comprises a ceramic-based material (e). Ceramic-based materials are known in the art and comprise oxide ceramic materials, non-oxide ceramic materials, and composite ceramic materials. An example of oxide ceramic materials are mixed metal oxide ceramic materials. Typically, the ceramic-based material (e) is different from the materials of (a), (b), (c), and (d) described above. In particular embodiments, the concentration of ceramic-based materials in the compositions envisaged herein is between 0.5-30 wt%, more particularly between 5-25 wt%. More particularly, concentrations of between 10- 25% of the ceramic-based material are envisaged. In particular embodiments, concentrations of between 10-20 wt% of the ceramic-based material are envisaged.

In a preferred embodiment of the composition according to the invention, the ceramic-based material (e) is a mixed metal oxide ceramic material. In a further preferred embodiment of the composition according to the invention, the ceramic-based material (e) is a mixed ionic-electronic conducting (MIEC) material. MIEC materials are known in the art, and are typically composed of mixed metal oxides exhibiting selective ionic and/or electronic conductivity. Preferably, the MIEC material is selected from the group consisting of MIEC perovskites. Indeed, it was observed that MIEC perovskites can ensure an improved thermal expansion match between the membrane and substrate and further reduces the softening temperature. In particular embodiments, the concentration of ceramic-based materials in the compositions envisaged herein is between 0.5-30 wt%, more particularly between 5-25 wt%. More particularly, concentrations of between 10- 25% of ceramic-based materials are envisaged. In specific embodiments, concentrations of between 10 and 20 wt% of the ceramic-based materials are envisaged.

Perovskites are known in the art, and have the general formula ABO3, wherein A is an alkaline cation, an alkaline earth cation or a rare earth cation, and B is a transition metal cation. Perovskite compounds having a deficiency in cations, anions or both have the general formula ΑΒ03_δ. Examples of perovskites having the formula ABO3 or AB0₃_ δ include CaTi0₃, SrFe0₃_5, SrTi0₃_5 and EuTi0₃_5. Teraoka et αί, Chemistry Letters 1985, 1743 - 1746, incorporated by reference herein, describe that vacancy defect concentration (δ), and consequently ionic diffusion, was enhanced by doping the cation sites (A or B) with other cations (A' or B') of different sizes and/or valences, resulting in a perovskite of the general formula Α_χΑΊ__χΒ_γΒΊ__γ0₃_δ.

In a preferred embodiment of the composition according to the invention, the ceramic-based material (e) is a mixed ionic-electronic conducting (MIEC) material according to the general formula A_xA'i__xB_yB'i_y0₃_6, wherein A and A' are independently selected from the group consisting of alkaline cations, alkaline earth cations and rare earth cations; B and B' are independently selected from the group consisting of transition metal cations, Al cations, Ga cations and In cations; x is 0 < 1; and y is 0 < 1 ; or the ceramic- based material (e) is a MIEC material according to the general formula A_xA'_xA"_X"ByB'y'B"y"03-6, wherein A, A' and A" are independently selected from the group consisting of alkaline cations, alkaline earth cations and rare earth cations; B, B' and B" are independently selected from the group consisting of transition metal cations, Al cations, Ga cations and In cations; x, x' and x" are 0 < 1; y, y' and y" are 0 < 1; x + x' + x" = 1 ; and y + y' + y" = 1. As is known to a person skilled in the art, the term δ represents the number of vacancies or defects in the crystal lattice.

More preferably, said MIEC material is according to the general formula

A_xA'i__xByB'i_y03-6 as defined above, or according to the general formula A_xA'_xA"_X"B_yB'y'B"y"03-6 as defined above, wherein x" is 0. Most preferably, said MIEC material is according to the general formula A_xA'i__xB_yB'i_y03_6 as defined above.

Preferably, A, A' and A" are independently selected from the group consisting of La, Na, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, Y, Be, Ca, Sr, Ba and Ra cations. Preferably, B, B' and B" are independently selected from the group consisting of Ga, Al, In, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Ta, Y, Mg and Zr cations. More preferably, A, A' and A" are independently selected from the group consisting of La, Na, Ca, Sr and Ba cations and B, B' and B" are independently selected from the group consisting of Fe, Co, Ni, Cu, Nb, Ti, Zr, Al, Ga and In cations.

In a further preferred embodiment of the composition according to the invention, said ceramic material is a mixed ionic-electronic conducting (MIEC) material according to the general formula A_xA'i__xB_yB'i_y03_6 or according to the general formula A_xA_xA"_X"B_yBVB"_y"0₃-₅, wherein A, A, A", B, B*, B" x, x*, x", y, y* and y" are as defined above, and wherein said ceramic material is selected from the group consisting of BFZ (wherein B represents Ba, F represents Fe and Z represents Zr), BLF (wherein B represents Ba, L represents La and F represents Fe), BSCF (wherein B represents Ba, S represents Sr, C represents Co and F represents Fe), BCFZ (wherein B represents Ba, C represents Co, F represents Fe and Z represents Zr), BSCFZ (wherein B represents Ba, S represents Sr, C represents Co, F represents Fe and Z represents Zr), SCF (wherein S represents Sr, C represents Co and F represents Fe), CSTF (wherein C represents Ca, S represents Sr, T represents Ti and F represents Fe), CTF (wherein C represents Ca, T represents Ti and F represents Fe), LCC (wherein L represents La, the middle C represents Ca and the last C represents Co), LSCF (wherein L represents La, S represents Sr, C represents Co and F represents Fe), LSF (wherein L represents La, S represents Sr, and F represents Fe), LSFZ (wherein L represents La, S represents Sr, F represents Fe and Z represents Zr) LSFG (wherein L represents La, S represents Sr, F represents Fe and G represents Ga), LSTF (wherein L represents La, S represents Sr, T represents Ti and F represents Fe), SCFZ (wherein S represents Sr, C represents Co, F represents Fe and Z represents Zr), LSFN (wherein L represents La, S represents Sr, F represents Fe and N represents Ni), LSFNb (wherein L represents La, S represents Sr, F represents Fe and Nb represents Nb) and LSCN (wherein L represents La, S represents Sr, C represents Co and N represents Ni) .

More preferably, BFZ is BaFeo.975Zr₀.o₂50₃_6, BLF is Bao.95La₀.o5Fe0₃_6, BSCF is Ba₀.5Sro.5Coo.8Feo.20₃-6, BSCFZ is Bao.₅Sro.5(Coo.8Feo.2)o.97Zro.o30₃_6, BCFZ is BaCo₀.4Feo.4Zro.₂0₃_6, SCF is SrCoo.8Fe₀.₂0₃_6, CSTF is Cao.₈Sro.₂Tio.₇Feo.303-5, CTF is CaTio.9Feo.i0₃_6 or CaTio.₇Feo.₃0₃_6, LCC is Lao.6Ca₀.4Co0₃_6, LSCF is Lao.₆Sro.4Coo.2Feo.80₃_6, LSF is La₀.5Sro.₅Fe0₃_6 or Lao.8Sr₀.₂Fe0₃_6, LSFZ is Lao.₂Sro.8Feo.9Zro.i0₃_6, LSFG is

LSTF is Lao.6Sro.4Tio.₃Feo.₇0₃_6, SCFZ is SrCo₀.4Feo.₅Zro.i0₃_₆, LSFN is Lao^Sro.sFeo.sNio^O^, LSFNb is La₀.2Sro.8Feo.8Nbo.₂0₃_6, and/or LSCN is Lao.eSro^Coo.sNio^O^. The composition according to the invention may further comprise a liquid medium

(f). Said liquid medium (f) may be water or a non-aqueous liquid medium. Preferably said liquid medium (f) is a non-aqueous liquid medium. By the addition of a liquid medium the composition can be formed into a paste. The liquid medium is therefore present in the composition in an amount that is sufficient to ensure that the composition is in the form of a paste. Examples of a liquid medium include water, alcohols, preferably alcohols having 1 to 8 C-atoms (e.g. methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t- butanol), ketones (e.g. acetone), halogenated solvents (e.g. chloroform, dichloromethane), aromatic solvents (e.g. toluene, xylene), ethers (e.g. diethyl ether), alkanes having 5 to 16 C-atoms (e.g. pentane, hexane, heptane), and mixtures thereof. Preferably, the liquid medium is an alcohol, more preferably an alcohol having 1 to 8 C-atoms, even more preferably an alcohol selected from the group consisting of methanol, ethanol, n- propanol, i-propanol, n-butanol, i-butanol and t-butanol.

The present invention therefore also relates to a composition comprising: (a) 22 - 55 wt.% Si0₂,

(b) 2 - 15 wt.% MO wherein M is Mg or Zn,

(c) 15 - 48 wt.% BaO,

(d) 2 - 30 wt.% Bi₂0₃,

(e) 0.5 - 25 wt.% ceramic-based material (other than (a), (b), (c), and (d)), and

(f) a liquid medium.

wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight of the composition excluding any liquid medium, as described hereabove.

Accordingly, the amount of liquid medium (f) present in said composition has no influence on the amounts in wt.% of (a), (b), (c), (d) and (e).

In a preferred embodiment, the composition according to the invention comprises (a) 25 - 55 wt.% Si0₂, (b) 2 - 15 wt.% MO wherein M is Mg or Zn, (c) 15 - 40 wt.% BaO, (d) 2 - 30 wt.% Bi₂0₃, (e) 2 - 25 wt.% ceramic-based material and (f) a liquid medium, wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight of the composition excluding said liquid medium, and wherein the composition is in the form of a paste. In another preferred embodiment, the composition according to the invention consists essentially of (a) 25 - 55 wt.% Si0₂, (b) 2 - 15 wt.% MO wherein M is Mg or Zn, (c) 15 - 40 wt.% BaO, (d) 2 - 30 wt.% Bi₂0₃, (e) 2 - 25 wt.% ceramic-based material and (f) a liquid medium, wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight of the composition excluding said liquid medium, and wherein the composition is in the form of a paste.

In a further preferred embodiment, the composition according to the invention comprises (a) 30 - 50 wt.% Si0₂, (b) 3 - 13 wt.% MO wherein M is Mg or Zn, (c) 18 - 35 wt.%) BaO, (d) 5 - 25 wt.% Bi₂0₃, (e) 2 - 20 wt.% ceramic-based material and (f) a liquid medium, wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight of the composition excluding said liquid medium, and wherein the composition is in the form of a paste. In another preferred embodiment, the composition according to the invention consists essentially of (a) 30 - 50 wt.% Si0₂, (b) 3 - 13 wt.% MO wherein M is Mg or Zn, (c) 18 - 35 wt.% BaO, (d) 5 - 25 wt.% Bi₂0₃, (e) 2 - 20 wt.% ceramic-based material and (f) a liquid medium, wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight of (a), (b), (c), (d) and (e) in the composition, i.e. the total weight of the composition excluding said liquid medium, and wherein the composition is in the form of a paste.

In a more preferred embodiment, the composition according to the invention comprises (a) 32 - 48 wt.% Si0₂, (b) 4 - 10 wt.% MO wherein M is Mg or Zn, (c) 20 - 30 wt.% BaO, (d) 10 - 23 wt.% Bi₂0₃, (e) 3 - 18 wt.% ceramic-based material and (f) a liquid medium, wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight of the composition excluding said liquid medium, and wherein the composition is in the form of a paste. In another more preferred embodiment, the composition according to the invention consists essentially of (a) 32 - 48 wt.% Si0₂, (b) 4 - 10 wt.% MO wherein M is Mg or Zn, (c) 20 - 30 wt.% BaO, (d) 10 - 23 wt.% Bi₂0₃, (e) 3 - 18 wt.% ceramic-based material and (f) a liquid medium, wherein the amounts in wt.%) of (a), (b), (c), (d) and (e) are based on the total weight of (a), (b), (c), (d) and (e) in the composition, and wherein the composition is in the form of a paste.

In an even more preferred embodiment, the composition according to the invention comprises (a) 35 - 45 wt.% Si0₂, (b) 5 - 8 wt.% MO wherein M is Mg or Zn, (c) 22 - 28 wt.% BaO, (d) 13 - 20 wt.% Bi₂0₃, (e) 4 - 15 wt.% ceramic-based material and (f) a liquid medium, wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight of the composition excluding said liquid medium, and wherein the composition is in the form of a paste. In another even more preferred embodiment, the composition according to the invention consists essentially of (a) 35 - 45 wt.% Si0₂, (b) 5 - 8 wt.% MO wherein M is Mg or Zn, (c) 22 - 28 wt.% BaO, (d) 13 - 20 wt.% Bi₂0₃, (e) 4 - 15 wt.% ceramic-based material and (f) a liquid medium, wherein the amounts in wt.%) of (a), (b), (c), (d) and (e) are based on the total weight of (a), (b), (c), (d) and (e) in the composition, and wherein the composition is in the form of a paste.

Most preferably, the composition according to the invention comprises (a) 37 - 43 wt.% Si0₂, (b) 6 - 7.5 wt.% MO wherein M is Mg or Zn, (c) 23 - 27 wt.% BaO, (d) 15 - 19 wt.%) Bi₂0₃, (e) 5 - 14 wt.% ceramic-based material and (f) a liquid medium, wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight of the composition excluding said liquid medium, and wherein the composition is in the form of a paste. In another most preferred embodiment, the composition consists essentially of (a) 37 - 43 wt.% Si0₂, (b) 6 - 7.5 wt.% MO wherein M is Mg or Zn, (c) 23 - 27 wt.% BaO, (d) 15 - 19 wt.%) Bi₂0₃, (e) 5 - 14 wt.% ceramic-based material and (f) a liquid medium, wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight of (a), (b), (c), (d) and (e) in the composition, and wherein the composition is in the form of a paste.

The joining/sealing composition according to the invention is preferably prepared by mixing a glass matrix composition comprising the appropriate amounts of Si0₂, MO wherein M is Mg or Zn (preferably Mg), and BaO, with the appropriate amounts of Bi₂0₃ and a ceramic based material, and optionally a liquid medium. The ceramic based material and the liquid medium are described in more detail above.

As was described above, in a preferred embodiment of the joining/sealing composition according to the invention, (a), (b) and (c) are comprised in a glass matrix composition. The term "glass matrix composition" herein refers to a glass composition comprising Si0₂, MO wherein M is Mg or Zn (preferably Mg), and BaO. Preferably, the glass matrix composition is a particulate composition. Said glass composition may be used in the preparation of the joining/sealing composition according to the invention.

The present invention therefore also relates to a glass matrix composition comprising:

(A) 54 - 78 mol% Si0₂,

(B) 8 - 19 mol% MO, wherein M is Zn or Mg, and

(C) 14 - 27 mol% BaO,

wherein the amounts of (A), (B) and (C) are based on the total amount of moles Si0₂, MO and BaO present in the glass matrix composition.

In certain embodiments the glass matrix composition comprises (A) 48.8-56.8 w% Si0₂, (B) 5.6 -8 w% MO, wherein M is Zn or Mg, and (C) 37.6 - 43.2 w% BaO, wherein the amounts of (A), (B) and (C) are based on the total weight of Si0₂, MO and BaO present in the glass matrix composition.

In certain embodiments the glass matrix composition comprises (A) 39.8-65.5 w% Si0₂,

(B) 4.5-9.4 w% MgO, and (C) 30.0-50.8 w% BaO, wherein the amounts of (A), (B) and

(C) are based on the total weight of Si0₂, MgO and BaO present in the glass matrix composition.

In certain embodiments the glass matrix composition comprises (A) 36.3-62.6 w% Si0₂, (B) 8.7 -17.3 w% ZnO, and (C) 28.7 - 46.4 w% BaO, wherein the amounts of (A), (B) and (C) are based on the total weight of Si0₂, ZnO and BaO present in the glass matrix composition. In certain embodiments, the above-mentioned amounts of (A), (B) and (C) in w% are based on the total weight of the glass matrix composition.

In preferred embodiments, the glass matrix composition comprises:

(A) 62 - 72 mol% Si0₂,

(B) 14 - 19 mol% MO, wherein M is Zn or Mg, and

(C) 14 - 19 mol% BaO,

wherein the amounts of (A), (B) and (C) are based on the total amount of moles Si0₂, MO and BaO present in the glass matrix composition. The inventors have found that such glass matrix compositions can provide particularly good joints with the method for providing a joint as described herein.

In certain embodiments the glass matrix composition comprises (A) 54.0-57.9 w% Si0₂, (B) 8.8-9.6 w% MO, wherein M is Zn or Mg, and (C) 33.3-36.4 w% BaO, wherein the amounts of (A), (B) and (C) are based on the total weight of Si0₂, MO and BaO present in the glass matrix composition.

In certain embodiments the glass matrix composition comprises (A) 50.3-61.5 w% Si0₂,

(B) 8.0-10.3 w% MgO, and (C) 30.5-39.3 w% BaO, wherein the amounts of (A), (B) and

In certain embodiments the glass matrix composition comprises (A) 45.5-56.8 w% Si0₂,

(B) 15.0-18.9 w% ZnO, and (C) 28.2-35.6 w% BaO, wherein the amounts of (A), (B) and

(C) are based on the total weight of Si0₂, ZnO and BaO present in the glass matrix composition.

In certain embodiments, the above-mentioned amounts of (A), (B) and (C) in w% are based on the total weight of the glass matrix composition.

In a further preferred embodiment, the glass matrix composition comprises (A) 64 - 70 mol% Si0₂, (B) 15 - 18 mol% MO, wherein M is Zn or Mg, and (C) 15 - 18 mol% BaO, wherein the amounts of (A), (B) and (C) are based on the total amount of moles Si0₂, MO and BaO present in the glass matrix composition. In an even further preferred embodiment, the glass matrix composition comprises (A) 65 - 69 mol% Si0₂, (B) 15.5 - 17.5 mol% MO, wherein M is Zn or Mg, and (C) 15.5 - 17.5 mol% BaO, wherein the amounts of (A), (B) and (C) are based on the total amount of moles Si0₂, MO and BaO present in the glass matrix composition. In yet an even further preferred embodiment, the glass matrix composition comprises (A) 66 - 68 mol% Si0₂, (B) 16 - 17 mol% MO, wherein M is Zn or Mg, and (C) 16 - 17 mol% BaO, wherein the amounts of (A), (B) and (C) are based on the total amount of moles Si0₂, MO and BaO present in the glass matrix composition. Most preferably, the glass matrix composition comprises (A) 66.6 - 67.4 mol% Si0₂, (B) 16.3 - 16.7 mol% MO, wherein M is Zn or Mg, and (C) 16.3 - 16.7 mol% BaO, wherein the amounts of (A), (B) and (C) are based on the total amount of moles Si0₂, MO and BaO present in the glass matrix composition. In a further preferred embodiment, the glass matrix composition consists essentially of the components (A), (B) and (C).

The glass matrix composition is preferably prepared by a process comprising the steps of:

(1) providing a mixture of the appropriate amounts of Si0₂, MCO3 wherein M is Zn or Mg (preferably Mg), and BaC0₃,

(2) heating the mixture to a temperature in the range of about 1400 to about 1600 °C, followed by

(3) quenching the mixture in a suitable quenching medium (preferably water).

The term "in the appropriate amounts" refers to the amounts of Si0₂, MC0₃ and

BaC0₃ as herein defined for the glass matrix composition and the joining/sealing composition.

As mentioned above, the glass matrix composition according to the invention is preferably a particulate composition, more preferably a powder. With respect to the particle size distribution of the glass matrix composition, it is preferred that dio is in the range of 1.5 to 5 μιη, d₅o is in the range of 3 to 42 μιη, and dgo is in the range of 30 to 200 μιη. More preferably, dio is in the range of 1.5 to 3 μιη, d₅o is preferably in the range of 3 to 11 μιη, and dgo is preferably in the range of 30 to 91 μιη.

As mentioned above, the joining/sealing composition according to the invention is preferably a particulate composition, more preferably a powder. With respect to the particle size distribution of the glass matrix composition particles, it is preferred that dio, d₅o and dgo are as described above. With respect to the particle size distribution of the Bi₂0₃ particles, it is preferred that dio is in the range of 2 to 5 μιη, d₅o is in the range of 5 to 20 μηι, and dgo is in the range of 20 to 50 μηι, more preferably d₁₀ is in the range of 3 to 4 μιη, d₅o is in the range of 7 to 10 μιη, and dgo is in the range of 15 to 30 μιη. With respect to the particle size distribution of the ceramic material particles, it is preferred that d₅o is in the range of 1 to 5 μιη, more preferably in the range of 2 to 3 μιη.

In a particular embodiment of the joining/sealing composition according to the invention, the composition comprises:

(I) a glass matrix composition comprising:

(A) 54 - 78 mol% Si0₂,

(B) 8 - 19 mol% MO, wherein M is Zn or Mg, and

(C) 14 - 27 mol% BaO,

wherein the amounts of (A), (B) and (C) are based on the total amount of moles Si0₂, MO and BaO present in the glass matrix composition,

(II) 5 - 40 wt.% Bi₂0₃, and

(III) 1 - 40 wt.% ceramic-based material,

wherein the amounts of (II) and (III) are based on the total weight of glass matrix composition (I).

The glass matrix composition (I), the ceramic-based material (III), and preferred embodiments thereof are described in more detail above.

In this particular embodiment of the joining/sealing composition according to the invention, it is preferred that the glass matrix composition comprises:

(A) 62 - 72 mol% Si0₂,

(B) 14 - 19 mol% MO, wherein M is Zn or Mg, and

(C) 14 - 19 mol% BaO,

Additionally or alternatively, it is preferred that the composition comprises (II) 5 - 40 wt.% Bi₂0₃ and (III) 3 - 30 wt.% ceramic-based material, wherein the amounts of (II) and (III) are based on the total weight of glass matrix composition (I). It is further preferred that the composition comprises (II) 10 - 35 wt.% Bi₂0₃ and (III) 5 - 25 wt.% ceramic-based material, wherein the amounts of (II) and (III) are based on the total weight of glass matrix composition (I). More preferably, the composition comprises (II) 15 - 30 wt.% B1₂O₃ and (III) 8 - 25 wt.% ceramic-based material, wherein the amounts of (II) and (III) are based on the total weight of glass matrix composition (I).

Also in this particular embodiment, the joining/sealing composition may further comprise a liquid medium. The liquid medium and preferred embodiments thereof are described in more detail above.

In this particular embodiment of the joining/sealing composition according to the invention, the composition comprises:

(I) a glass matrix composition comprising:

(A) 54 - 78 mol% Si0₂,

(B) 8 - 19 mol% MO, wherein M is Zn or Mg, and

(C) 14 - 27 mol% BaO,

(II) 5 - 40 wt.% Bi₂0₃,

(III) 1 - 40 wt.% ceramic-based material, and

(IV) a liquid medium,

wherein the amounts of (II) and (III) are based on the total weight of glass matrix composition (I), and wherein the composition is in the form of a paste.

Preferably, the composition comprises (I) a glass matrix composition comprising (A) 62- 72 mol% Si0₂; (B) 14 - 19 mol% MO, wherein M is Zn or Mg; and (C) 14 - 19 mol%

BaO.

Additionally or alternatively, the composition preferably comprises (II) 5 - 40 wt.% B1₂O₃ and (III) 3 - 30 wt.% ceramic-based material, wherein the amounts of (II) and (III) are based on the total weight of glass matrix composition (I), and wherein the composition is in the form of a paste. More preferably, the composition comprises (II) 10 - 35 wt.% B1₂O₃ and (III) 5 - 25 wt.% ceramic-based material, wherein the amounts of (II) and (III) are based on the total weight of glass matrix composition (I), and wherein the composition is in the form of a paste. Most preferably, the composition comprises (II) 15 - 30 wt.% B1₂O₃ and (III) 8 - 25 wt.% ceramic-based material, wherein the amounts of (II) and (III) are based on the total weight of glass matrix composition (I), and wherein the composition is in the form of a paste. Alternatively, the glass matrix composition according to the invention may additionally comprise the appropriate amount of B1₂O₃. Said glass matrix composition comprising B1₂O₃ is preferably prepared as described above. The joining/sealing composition according to the invention may therefore also be prepared by first preparing a glass matrix composition comprising the appropriate amounts of Si0₂, MO wherein M is Mg or Zn (preferably Zn), BaO and B1₂O₃, followed by mixing said glass matrix composition with the appropriate amount of a ceramic based material, and optionally a liquid medium. The ceramic based material and liquid medium are described in more detail above.

The invention further relates to the use of a joining/sealing composition according to the invention in a method for providing a joint between a ceramic component and a substrate. Method for providing a joint

The present invention also relates to the use of the joining/sealing composition according to the invention for providing a joint or a seal between a ceramic component and a substrate.

The invention therefore relates to a method for providing a joint between a ceramic component and a substrate, wherein the method comprises the steps of:

(i) providing a joining/sealing composition according to the invention,

As was described above, the term "joint" includes the term "seal". When a joint is gas tight, said joint is herein also referred to as a seal. In a preferred embodiment of the method for providing a joint according to the invention, the joint that is formed in said method is a seal.

The sealing/joining composition according to the invention, and preferred embodiments thereof, are described in more detail above. Consequently, in the method according to the invention for providing a joint between a ceramic component and a substrate, any composition or preferred embodiment thereof as described above may be provided in step (i) of said method.

In a particular embodiment, the method for providing a joint between a ceramic component and a substrate comprises the steps of:

(i) providing a composition comprising:

(a) 22 - 55 wt.% Si0₂,

(b) 2 - 15 wt.% MO wherein M is Mg or Zn,

(c) 15 - 48 wt.% BaO,

(d) 2 - 30 wt.% Bi₂0₃,

(f) optionally, a liquid medium;

wherein the amounts in wt.% of (a), (b), (c), (d), and (e) are based on the total weight of the composition excluding any liquid medium (if present); (ii) contacting the composition with the ceramic component and the substrate; and

Preferred embodiments of the joining/sealing composition referred to in step (i) of the method according to the invention are described in more detail above.

As was described above, the term "joint" herein refers to a connection between two (or more) components, in particular to a connection between one or more ceramic components and one or more additional components. The one or more additional components are herein also referred to as "substrate" or "substrates". Said ceramic component(s) and substrate(s) are bonded together by the joint.

The term "ceramic component" refers to an article comprising a ceramic material. Said article may also comprise a mixture of two or more ceramic materials, and when more than one ceramic component is present, each ceramic component may comprise a different ceramic material. The ceramic component is at least partly composed of a ceramic material, and in a particular embodiment the ceramic component consists essentially of a ceramic material. In the method according to the invention, a joint is formed between ceramic material of the ceramic component, and one or more substrates. The one or more ceramic components comprise a ceramic material. Ceramic-based materials are known in the art and comprise oxide ceramic materials, non-oxide ceramic materials and composite ceramic materials. An example of oxide ceramic materials are mixed metal oxide ceramic materials. In a preferred embodiment of the composition according to the invention, the ceramic-based material (e) is a mixed metal oxide ceramic material.

In a further preferred embodiment of the method for providing a joint between a ceramic component and a substrate according to the invention, the ceramic component comprises a mixed ionic-electronic conducting (MIEC) material. MIEC materials are known in the art, and are typically composed of mixed metal oxides exhibiting selective ionic and/or electronic conductivity. Preferably, the MIEC material is selected from the group consisting of MIEC perovskites. MIEC materials and MIEC perovskites are described in more detail above.

In a preferred embodiment of the method according to the invention, the ceramic component comprises a MIEC material according to the general formula ABO3 or ΑΒ03_δ. In another preferred embodiment the ceramic component comprises a MIEC material according to the general formula A_xA'i__xB_yB'i_y03_6, wherein A and A' are independently selected from the group consisting of alkaline cations, alkaline earth cations and rare earth cations; B and B' are independently selected from the group consisting of transition metal cations, Al cations, Ga cations and In cations; x is 0 < 1 ; and y is 0 < 1. In another preferred embodiment, the ceramic component comprises a MIEC material according to the general formula A_XA'_X Α"_Χ"Β_γΒ'_γΒ"_γ θ3_δ, wherein A, A' and A" are independently selected from the group consisting of alkaline cations, alkaline earth cations and rare earth cations; B, B' and B" are independently selected from the group consisting of transition metal cations, Al cations, Ga cations and In cations; x, x' and x" are 0 < 1 ; y, y' and y" are 0 < 1 ; x + x' + x" = 1 ; and y + y' + y" = 1. As is known to a person skilled in the art, the term δ represents the number of vacancies or defects in the crystal lattice.

More preferably, said MIEC material is according to the general formula A_xA'i__xB_yB'i__y0₃-6 as defined above, or according to the general formula A_xA'_xA"_X"ByB'y'B"y"03-6 as defined above, wherein x" is 0. Most preferably, said MIEC material is according to the general formula A_xA'i__xB_yB'i_y03_6 as defined above. Preferably, A, A' and A" are independently selected from the group consisting of La, Na, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, Y, Be, Ca, Sr, Ba and Ra cations. Preferably, B, B' and B" are independently selected from the group consisting of Ga, Al, In, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Ta, Y, Mg and Zr cations. More preferably, A, A' and A" are independently selected from the group consisting of La, Na, Ca, Sr and Ba cations and B, B' and B" are independently selected from the group consisting of Fe, Co, Ni, Cu, Nb, Ti, Zr, Al, Ga and In cations.

In a further preferred embodiment of the method according to the invention, the ceramic component comprises a MIEC material according to the general formula A_xA'i__xByB'i_y03-6 or according to the general formula Α_χΑ'_χΑ"_Χ"Β_γΒ'_Υ'Β"_Υ"0₃_δ, wherein A, A', A", B, B', B" x, x', x", y, y' and y" are as defined above, and wherein said ceramic material is selected from the group consisting of BFZ (wherein B represents Ba, F represents Fe and Z represents Zr), BLF (wherein B represents Ba, L represents La and F represents Fe), BSCF (wherein B represents Ba, S represents Sr, C represents Co and F represents Fe), BCFZ (wherein B represents Ba, C represents Co, F represents Fe and Z represents Zr), BSCFZ (wherein B represents Ba, S represents Sr, C represents Co, F represents Fe and Z represents Zr), SCF (wherein S represents Sr, C represents Co and F represents Fe), CSTF (wherein C represents Ca, S represents Sr, T represents Ti and F represents Fe), CTF (wherein C represents Ca, T represents Ti and F represents Fe) LCC (wherein L represents La, the middle C represents Ca and the last C represents Co), LSCF (wherein L represents La, S represents Sr, C represents Co and F represents Fe), LSF (wherein L represents La, S represents Sr, and F represents Fe), LSFZ (wherein L represents La, S represents Sr, F represents Fe and Z represents Zr) LSFG (wherein L represents La, S represents Sr, F represents Fe and G represents Ga), LSTF (wherein L represents La, S represents Sr, T represents Ti and F represents Fe), SCFZ (wherein S represents Sr, C represents Co, F represents Fe and Z represents Zr), LSFN (wherein L represents La, S represents Sr, F represents Fe and N represents Ni), LSFNb (wherein L represents La, S represents Sr, F represents Fe and Nb represents Nb) and LSCN (wherein L represents La, S represents Sr, C represents Co and N represents Ni). More preferably, BFZ is BaFeo.975Zr₀.o250₃-6, BLF is Ba₀.95La₀.05FeO₃_6, BSCF is Bao.₅Sr₀.₅Coo.8Feo.₂C>3-5, BSCFZ is Bao.₅Sro.5(Coo.8Feo.2)o. 7Zro.o₃0₃_6, BCFZ is BaCo₀.4Feo.4Zro.₂0₃_6, SCF is SrCoo.8Fe₀.₂0₃_6, CSTF is Cao.8Sro.₂Tio.₇Feo.₃0₃_6, CTF is CaTio.₉Fe₀.i0₃_6 or CaTio.₇Feo.₃0₃_6, LCC is La₀.6Ca₀.4CoO₃_6, LSCF is Lao.6Sr₀.4Coo.₂Feo.80₃_6, LSF is La₀.5Sro.₅Fe03-6 or Lao.₈Sr₀.₂Fe0₃-5, LSFZ is

LSFG is La₀.6Sro.4Feo. Gao.i0₃-6, LSTF is Lao.₆Sro.₄Tio.₃Feo.₇C>₃-5, SCFZ is

LSFN is Lao.₂Sr₀.₈Fe₀.₈Nio.₂0₃-5, LSFNb is Laa₂Sr₀.₈Fe₀.₈Nb₀.₂O₃-5, and/or LSCN is La₀.6Sro.4Coo.8Nio.203-6.

In a preferred embodiment of the method for providing a joint between a ceramic component and a substrate according to the invention, the ceramic component comprises a ceramic membrane, more preferably a mixed ionic-electronic conducting (MIEC) ceramic membrane. MIEC ceramic membranes are known in the art, and are typically composed of MIEC materials. MIEC materials and preferred embodiments thereof are described in more detail above. In a preferred embodiment of the method according to the invention, the ceramic component comprises a MIEC ceramic membrane selected from the group consisting of BFZ, BLF, BSCF, BSCFZ, BCFZ, SCF, CSTF, CTF, LCC, LSCF, LSF, LSFZ, LSFG, LSTF, SCFZ, LSFN, LSFNb, LSCN (all as defined above), and a combination thereof. More preferably, BFZ is BaFeo. ₇₅Zro.o₂₅0₃_6, BLF is Ba₀.95Lao.o5Fe0₃-6, BSCF is Bao.₅Sr₀.₅Coo.₈Fe₀.₂0₃-5, BSCFZ is Bao.5Sro.5(Coo.8Feo.2)o.97Zro.o30₃-6, BCFZ is BaCoo.₄Feo.₄Zr₀.₂0₃-5, SCF is SrCo₀.8Fe₀.2O₃-6, CSTF is Cao.₈Sro.₂Tio.₇Feo.₃0₃-6, CTF is CaTio.gFeo.iCh-e, LCC is La₀.₆Cao.₄Co0₃-6, LSCF is La₀.6Sro.4Coo.2Feo.80₃-6, LSF is Lao.₅Sr₀.₅Fe0₃-5 or Lao.₈Sr₀.₂Fe0₃-5, LSFZ is La₀.2Sro.8Feo.9Zro.i0₃-6, LSFG is

LSTF is Lao.₆Sro.₄Tio.₃Feo.₇C>₃-5, SCFZ is SrCoo.4Feo.5Zro.i0₃-₅, LSFN is Lao^Sro.sFeo.sNio^C^, LSFNb is Laa₂Sr₀.₈Fe₀.₈Nb₀.₂O₃-5, and/or LSCN is Lao.eSro^Coo.sNio^C^.

In a preferred embodiment of the method according to the invention, the ceramic- based material (e), present in the joining/sealing composition referred to in step (i) of the method, is a mixed ionic-electronic conducting (MIEC) material. Preferred embodiments of ceramic-based material (e) are described in more detail above.

In another preferred embodiment, the ceramic-based material (e) present in the joining/sealing composition referred to in step (i) of the method according to the invention essentially matches the ceramic material comprised in the ceramic component to be joined. In other words, when the ceramic component to be joined to a substrate comprises a particular ceramic material, it is preferred that the joining/sealing composition comprises essentially the same ceramic material, i.e. it is preferred that component (e) of said composition also comprises that particular ceramic material.

In another preferred embodiment of the method for providing a joint between a ceramic component and a substrate, the substrate is selected from the group consisting of a ceramic substrate, a metal substrate, a metal alloy substrate, a cermet substrate, and combination thereof. The term "ceramic substrate" refers to an article comprising a ceramic material. Accordingly, the terms "metal substrate", "metal alloy substrate" and "cermet substrate" refer to a substrate comprising a metal, a metal alloy and a cermet material, respectively. Said article may also comprise a combination of two or more materials. For example, a substrate may comprise a metal and a ceramic material (such a substrate may be referred to as a metal/ceramic substrate), a ceramic material and a metal alloy (such a substrate may be referred to as a ceramic/metal alloy substrate), etc. When more than one substrate is present, each substrate may be different. For example, a first substrate may be a ceramic substrate and a second substrate may be a metal alloy substrate, or a first substrate may be a metal alloy substrate and a second substrate may be a ceramic/metal substrate, etc. A ceramic substrate is at least partly composed of a ceramic material, and accordingly a metal substrate is at least partly composed of a metal, a metal alloy substrate is at least partly composed of a metal alloy and a cermet substrate is at least partly composed of a cermet material. In the method according to the invention, a joint is formed between ceramic material, metal, metal alloy or cermet material of the one or more substrates, and the ceramic component.

Examples of a ceramic substrate include a substrate comprising a MIEC ceramic material, a substrate comprising zirconia, a substrate comprising YSZ (yttria stabilized zirconia), a substrate comprising AI₂O₃ and a substrate comprising mullite. Mullite is a mineral known in the art, and comprises AI₂O₃ and Si0₂. MIEC ceramic materials are described in detail above.

Examples of a metal substrate include a substrate comprising platinum, nickel, titanium, etc.

Examples of a metal alloy substrate include a stainless steel substrate, e.g. a

Crofer® substrate (such as a Crofer® 22 H, 22 APU), a Hastelloy substrate, Kanthal, Inconel 600, Incoloy 800, Steel 1.4841, etc. Examples of a cermet substrate include a substrate comprising a nickel-YSZ cermet. Cermet materials, i.e. composite material composed of ceramic and metallic materials, are known in the art. In a preferred embodiment of the method according to the invention, the joining/sealing composition referred to in step (i) of said process comprises MgO, i.e. in a preferred embodiment, M is Mg.

In step (ii) of the method according to the invention, the joining/sealing composition according to the invention is contacted with the one or more ceramic component and the one or more substrate. More particularly, said composition is applied at the interface of the one or more ceramic component and the one or more substrate that are to be joined. In step (iii) of the method according to the invention, the joining/sealing composition is heated to a sufficiently high temperature for a joint between the ceramic component and the substrate to be formed. Preferably, the temperature remains below the melting temperature of the glass matrix composition present in the joining/sealing composition. In a preferred embodiment of the method according to the invention, in step (iii) the composition is heated to a temperature in the range of 800 - 1400°C, preferably 800 - 1350°C. More preferably, the composition is heated to a temperature in the range of 850 - 1350°C, even more preferably in the range of 900 - 1300°C, even more preferably in the range of 950 - 1250°C, yet even more preferably in the range of 975 - 1225°C, yet even more preferably in the range of 1000 - 1 100°C, and most preferably in the range of 1030 - 1060°C.

Said joining/sealing composition is preferably heated to said temperature in a controlled manner, e.g. by gradually heating to the desired temperature, then maintaining the temperature during a certain amount of time, followed by gradually cooling down.

Preferably, step (iii) comprises a step of heating the composition to a temperature Ti, followed by keeping the temperature at Ti for a specific amount of time. Then, the composition is further heated to a temperature T₂, and kept at T₂ for a specific amount of time. In this embodiment, temperature T₂ is higher than temperature TV By heating the composition to temperature T_{l s} components (a) - (e) form a so called glass-ceramics composition. By further heating the composition to T₂, a joint between the ceramic component and the substrate is formed. Therefore, in a preferred embodiment of the method for providing a joint according to the invention, step (iii) comprises the steps of:

(iii-1) heating the composition to a temperature Ti and remaining the temperature at temperature Ti for a specific amount of time; and

(iii-2) further heating the composition to a temperature T₂.

As described above, temperature T₂ is higher than temperature Ti. Temperature T₂ is a temperature sufficiently high for a joint between the ceramic component and the substrate to be formed.

Preferably, in step (iii-1), the composition is heated to a temperature Ti in the range of about 300 - 1000°C, more preferably to a temperature Ti in the range of about 400 - 975°C, even more preferably to a temperature Ti in the range of about 500 to about 950°C and even more preferably to a temperature Ti in the range of about 600 - 950°C. Most preferably, in step (iii-1), the composition is heated to a temperature Ti in the range of about 700 - 950°C. In a further preferred embodiment, the temperature in step (iii-1) is raised gradually. In a further preferred embodiment, the temperature in step (iii-1) is raised with a rate in the range of about 20 - 120°C per hour, more preferably in the range of about 30 - 1 10°C per hour, even more preferably in the range of about 40 - 100°C per hour, even more preferably in the range of about 50 - 90°C per hour and most preferably in the range of about 60 - 80°C per hour. Even more preferably, in step (iii-1) the temperature is raised with a rate of about 20 - 120°C per hour, to a temperature in the range of about 500 - 950°C. Most preferably, in step (iii-1) the temperature is raised with a rate of about 40 - 100°C per hour, to a temperature in the range of about 700 - 950°C. As described above, the temperature is remained at temperature Ti for a specific amount of time. Preferably, the temperature is remained at temperature Ti for about 15 minutes or more, more preferably for about 30 minutes or more, even more preferably for about 45 minutes or more, even more preferably for about 60 minutes or more, and even more preferably for about 90 minutes or more. The temperature is for example remained at temperature Ti for about 60 to about 180 minutes, preferably for about 90 to about 150 minutes. In step (iii-2), the temperature is further increased to a temperature in the range of 800 - 1400°C. More preferably, the composition is heated to a temperature in the range of 850 - 1350°C, even more preferably in the range of 900 - 1350°C, even more preferably in the range of 950 - 1350°C, even more preferably in the range of 950 - 1300°C, yet even more preferably in the range of 975 - 1250°C, yet even more preferably in the range of 1000 - 1100°C, and most preferably in the range of 1030 - 1060°C.

As an example, in step (iii-1) the temperature may be raised with 60°C per hour to a temperature of 850°C, and the temperature may be kept at 850°C for e.g. 2 hours. Subsequently, in step (iii-2), the temperature may be raised from 850°C to 1030 - 1060°C with 180°C per hour, and kept at this temperature for e.g. 30 seconds to 10 minutes. The temperature may then for example be lowered with 180°C per hour to 900°C, kept at 900°C for 1 hour, and the temperature may then be further lowered to ambient temperature with 60°C per hour. Thus, in a particular embodiment of the method for providing a joint between a ceramic component and a substrate, the method comprises the steps of:

(i) providing a composition comprising:

(a) 22 - 55 wt.% Si0₂,

(b) 2 - 15 wt.% MO wherein M is Mg or Zn,

(c) 15 - 48 wt.% BaO,

(d) 2 - 30 wt.% Bi₂0₃,

(e) 0.5 - 25 wt.% ceramic-based material, and

(f) a liquid medium in order to form a paste of the composition, wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight the composition excluding said liquid medium;

As described above, in this embodiment it is preferred that step (iii) comprises steps

(iii-1) and (iii-2) as described in more detail above. Consequently, preferably step (iii) comprises the steps of: (iii-1) heating the composition to a temperature Ti and remaining the temperature at temperature Ti for a specific amount of time; and

(iii-2) further heating the composition to a temperature T₂.

Herein, T₂ is a sufficiently high temperature for a joint between the ceramic component and the substrate to be formed.

The composition referred to in step (i) and preferred embodiments thereof are described in more detail above. The liquid medium and preferred embodiments thereof are described in more detail above. In another particular embodiment of the method for providing a joint between a ceramic component and a substrate, the method comprises the steps of:

(i) providing a composition comprising:

(I) a glass matrix composition comprising:

(A) 54 - 78 mol% Si0₂,

(B) 8 - 19 mol% MO, wherein M is Zn or Mg, and

(C) 14 - 27 mol% BaO,

wherein the amounts of (A), (B) and (C) are based on the total amount in moles of Si0₂, MO and BaO present in the glass matrix composition,

(II) 5 - 40 wt.% Bi₂0₃,

(III) 1 - 40 wt.% ceramic-based material, and

(IV) a liquid medium in order to form a paste of the composition, wherein the amounts of (II) and (III) are based on the total weight of glass matrix composition (I);

In preferred embodiments, the a glass matrix composition (I) comprises (A) 62 - 72 mol% Si0₂; (B) 14 - 19 mol% MO, wherein M is Zn or Mg; and (C) 14 - 19 mol% BaO, wherein the amounts of (A), (B) and (C) are based on the total amount in moles of Si0₂, MO and BaO present in the glass matrix composition. As described above, it is preferred that step (iii) comprises steps (iii-1) and (iii-2) as described in more detail above. Consequently, preferably step (iii) comprises the steps of:

(iii-2) further heating the composition to a temperature T₂.

The composition referred to in step (i) and preferred embodiments thereof are described in more detail above. The temperatures Ti and T₂ and preferred embodiments thereof are described in more detail above. The amount of time the temperature is kept at Ti and preferred embodiments thereof is described in more detail above. The liquid medium and preferred embodiments thereof are described in more detail above.

As described above, in a particular embodiment of the method for providing a joint between a ceramic component and a substrate, the joining/sealing composition referred to in step (i) comprises a liquid medium in order to form a paste of the composition. The liquid medium and preferred embodiments thereof are described in more detail above.

When the joining/sealing composition referred to in step (i) of the method according to the invention further comprises a liquid medium, the composition may first be heated to a temperature below Ti in order to evaporate the liquid medium, in particular when the liquid medium has a high boiling point. Accordingly, in particular embodiments, step (iii-1) may comprise the steps of:

(iii- la) heating the composition to a sufficiently high temperature for the liquid medium to be removed; and

(iii- lb) further heating the composition to a temperature Ti and remaining the temperature at temperature Ti for a specific amount of time.

In this embodiment, the temperature is raised initially in step (iii- la) to a temperature sufficiently high for the liquid medium to evaporate from the composition. Subsequently, the temperature is further increased in step (iii- lb) to temperature T_{l s} wherein Ti sufficiently high for the glass ceramics composition to be formed.

As will be skilled to the person skilled in the art, in step (iii- la), it depends on the nature of the liquid medium to what temperature the composition is heated. When the liquid medium evaporates rapidly, e.g. ethanol, pentane or diethyl ether, said medium may already evaporate at ambient temperature and additional step (iii- la) may be omitted. When the liquid medium is e.g. water, it is preferred that in step (iii- la) the composition is heated to a temperature in the range of about 80 - 120°C, preferably in the range of about 90 - 110°C and more preferably to a temperature of about 100°C. Generally, in step (iii-la), the composition is heated to a temperature in the range of about 30 - 200°C, more preferably to a temperature in the range of about 40 - 150°C, even more preferably to a temperature in the range of about 50 - 120°C and most preferably to temperature in the range of about 80 - 110°C.

Joint between a ceramic component and a substrate

The invention further relates to a joint between a ceramic component and a substrate, wherein the joint is obtainable by the method for providing a joint between a ceramic component and a substrate according to the invention. In a particular embodiment, said joint between a ceramic component and a substrate is a seal between a ceramic component and a substrate. The method for providing a joint between a ceramic component and a substrate according to the invention and preferred embodiments thereof are described in more detail above.

The invention also relates to a joint between a ceramic component and a substrate, wherein the joint comprises a sealing/joining composition according to the invention. In a particular embodiment, said joint between a ceramic component and a substrate is a seal between a ceramic component and a substrate. The joining/sealing composition according to the invention and preferred embodiments thereof are described in more detail above. The skilled person will understand that where the joining/sealing composition comprises a liquid medium, the resulting joint/seal typically will no longer comprise said liquid medium. The compositions and joints provided herein have different applications in industry for connecting a ceramic material and another ceramic material, or a ceramic material and e.g. a metal or metal alloy. More particularly, the joints described herein are of interest where one or more of the following properties of the seal is beneficial: gastight connection, good wettability with both the membrane and the supporting structure, suitable viscosity and rigidity in the operating temperature range, chemically inertness at the operating temperature range, and a thermal expansion coefficient compatible with the membrane and the supporting structure in order to avoid thermal expansion mismatch leading to sealing failure caused by a temperature change. In particular embodiments, the application envisages the use of the materials described herein in the production of catalytic membrane reactors (CMR) and solid oxide fuel cells (SOFC) and the use of the joints described herein in CMR and SOFC.

In particular embodiments, the application envisages the use of the material envisaged herein for the manufacture of joints in devices or parts thereof which are subject to high temperatures, more particularly temperatures between 750° and 1000°C. In particular embodiments, said manufacture involves connecting a ceramic membrane, such as a dense mixed ionic electronic conducting (MIEC) ceramic membrane, to another material.

Accordingly, the application envisages the use of the joints as provided herein in a device which is designed for carrying out a chemical process which involves temperatures between 750° and 1000°C. The application further provides the use of a device for carrying out a chemical process which involves temperatures between 750° and 1000°C, whereby said device is characterized in that it comprises one or more joints as described herein.

In addition, the invention relates to a device, comprising a joint according to the invention. In a particular embodiment, the device comprises a seal according to the invention. In a preferred embodiment, said device is a membrane reactor (e.g. a catalytic membrane reactor, CMR) or a solid oxide fuel cell (SOFC).

A joint between a ceramic component and a substrate should have suitable thermal, chemical and mechanical properties. Both a joint and a joining/sealing composition preferably exhibits no detrimental chemical interactions with e.g. reactants it comes in contact with, is stable at the operating temperature for a specific application (e.g. up to about 1000°C), preferably during the lifetime of the device comprising the joint (e.g. up to several years). In addition to the properties of a joint, a seal has the additional property that it should be gastight.

The joint and the joining/sealing composition according to the present invention have a number of advantages. The composition of the joint and the joining/sealing composition according to the invention is easily adjustable, making it possible to tailor the properties of the joint, e.g. wettability, viscosity, chemical inertness, thermal expandability and bonding strength, to a specific application. For example, in order to obtain a gastight seal, it is important that the coefficient of thermal expansion (CTE) of the seal and of the material to be sealed is similar. The CTE of the seal according to the invention can be fine-tuned for a specific application by varying the sealing composition according to the invention.

Additional advantages are the absence of alkali oxides and the absence of B₂O₃ in the joints and seals according to the invention. The presence of alkali oxides in a glass seal has the disadvantage that reactions with the materials to be sealed may occur, e.g. with chromium in interconnections. In addition, the presence of alkali oxides generally leads to a significant mismatch in the coefficients of thermal expansion (CTE) of the seal and the materials to be sealed. The presence of boron leads to a lowering of the CTE of the seal. Also, boric acid volatilizes, leading to e.g. insulation of SOFC.

The joints and seals according to the invention generally have a lower fabrication and sealing temperature as compared to seals known from the prior art.

In addition, due to the presence of Bi₂0₃ and the ceramic-based material in the joints and seals according to the invention, increased wettability is obtained. Also, the joints and seals have a broad operating temperature range and are able to withstand thermal cycling. In addition, the seals according to the invention are gastight.

Additional advantages include e.g. that no binder is required in the seal composition to form a joint/seal.

Examples

Example 1: Preparation of a glass matrix composition

36.378 g BaC0₃ (MERCK, 197.35 g/mol), 15.5428 g MgC0₃ (SIGMA, 84.31 g/mol) and 44.30504 g Si0₂ (Aerosil FK 300, 60.09 g/mol) were mixed with acetone in a 21 PE jar together with Zr0₂-Y₂0₃ grinding balls (diameter 10 mm). The mixture was dried at 90°C in a furnace. After removing the grinding balls the obtained powder was compressed with an uni-axial press (100 bar) and a mold diameter of 34 mm. The obtained compressed powder disks were melted in a A1₂0₃ crucible in a furnace with a temperature profile of 80°C/h up to 1400°C, 6 min dwell at 1400°C and 180°C/h cooling down to 700°C. At 700°C, the powder was quenched in H₂0, and the obtained glass pieces were removed from the crucible. Dry milling of the glass pieces in an erthalon cup with 400 g of Zr0₂-Y₂0₃ grinding balls (diameter 10 mm), sieving of the powder with a 250 μηι sieve, milling of the fine glass powder in acetone with 400 g of Zr0₂-Y₂0₃ grinding balls (diameter 3 mm) during 15 min, drying of the powder and sieving of the powder with a 250 μιη sieve, resulted in 80 g of a glass matrix composition. The composition of the glass matrix composition was 67 mol% Si0₂, 16.5 mol% BaO and 16.5 MgO.

The thermal expansion coefficient of the glass matrix composition was 13 x 10^"6/°C (400 - 700 °C). The dilatometric softening temperature was 741°C. Example 2: Joining/sealing compositions

Several joining/sealing compositions A - R according to the invention are shown in Tables 1 and 2.

In Table 1, the amounts of Si0₂, MgO and BaO in the compositions are shown in mol%, based on the total number of moles of Si0₂, MgO and BaO present in the glass matrix composition. The amounts of Bi₂0₃ and membrane material in compositions A - R are shown in relative wt.%, based on the weight of the glass matrix composition in the composition according to the invention. For example, Composition A may be prepared by mixing 100 grams of the glass matrix composition (comprising 67 mol% Si0₂, 16.5 mol% MgO and 16.5 mol% BaO), 22 grams of Bi₂0₃, 8 grams of LSCF Treib and 2 grams of LSFN.

Table 1: Composition of several joining/sealing compositions A

invention ( amounts in mol% and relative wt. %).

Glass matrix composition

Comp. Si0₂ MgO BaO Bi₂0₃ Membrane material

(mo /o)¹ (mo /o)¹ (moiro)¹ (rel. wt.%)² (rel. wt.%)²

A 67 16.5 16.5 22 LSCF Treib³ (8 wt.%) and LSFNb⁴ (2 wt.%)

B 67 16.5 16.5 22 LSCF Treib³ (5 wt.%) and LSF⁵ (5 wt.%)

C 67 16.5 16.5 22 LSCF Treib³ (8 wt.%)

D 67 16.5 16.5 22 LSCF Treib³ (10 wt.%)

E 67 16.5 16.5 22 LSCF Treib³ (5 wt.%)

R 67 16.5 16.5 22 LSCF Treib³ (20 wt.%)

The amounts of Si0₂, MgO and BaO are based on the total number of moles of

Si0₂, MgO and BaO present in the glass matrix composition.

The amounts of Bi₂0₃ and membrane material in the composition are based on the weight of the glass matrix composition.

LSCF Treib: Lao.₆Sro.₄Coo.₂Feo.80₃-₆ Treibacher

LSFNb: Lao.₂Sro.8Feo.8Nbo.20₃-6 Cerpotech

LSF: Lao.5Sr₀.5Fe0₃-6 Cerpotech

LSCF Cerp: Lao.6Sro.4Coo.₂Feo.80₃-6 Cerpotech

LSFZ: Lao.₂Sro.8Feo.9Zro.i0₃-6 Cerpotech

CA: cellulose acetate butyrate (Aldrich)

BSCF Cerp: Bao.5Sro.5Coo.8Feo.₂0₃-6 Cerpotech BSCF Treib: Bao.sSro.sCoo.sFeo^Os-e Treibacher

1¹ BCFZ Cerp: BaCoo.4Feo.4Zr₀.₂03--6 Cerpotech

In Table 2, the same compositions A - R are shown, but the amounts of Si0₂, MgO and BaO are now shown in wt.%, based on the total weight of the composition according to the invention.

Table 2: Composition of several joining/sealing compositions A - R according to the invention (amounts in wt. %).

Glass matrix composition

Comp. Si0₂ MgO BaO Bi₂0₃ Membrane material

(wt.%)¹ (wt.%)¹ (wt.%)¹ (wt.%)² (wt.%)²

A 42.23 6.98 26.55 16.67 LSCF Treib³ (6.06 wt.%)

and LSFNb⁴ (1.52 wt.%)

B 42.23 6.98 26.55 16.67 LSCF Treib³ (3.79 wt.%)

and LSF⁵ (3.79 wt.%)

C 42.88 7.08 26.95 16.92 LSCF Treib³ (6.15 wt.%)

D 42.23 6.98 26.55 16.67 LSCF Treib³ (7.58 wt.%)

E 42.23 6.98 26.55 16.67 LSCF Treib³ (3.79 wt.%)

and LSCF Cerp⁶ (3.79 wt.%)

F 42.23 6.98 26.55 16.67 LSCF Treib³ (6.06 wt.%)

and LSFZ⁷ (1.52 wt.%)

G 43.05 7.11 27.06 16.99 CA⁸ (1.93 wt%)

BSCF Cerp⁹ (0.77 wt%) BSCF Treib¹⁰ (3.09 wt%)

H 42.23 6.98 26.55 16.67 BSCF Treib¹⁰ (7.58 wt%)

I 42.23 6.98 26.55 16.67 BCFZ Cerp¹¹ (3.79 wt%)

BSCF Treib¹⁰ (3.79 wt%)

J 44.60 7.37 28.03 4.00 BSCF Treib¹⁰ (16.00 wt%)

K 42.88 7.08 26.95 7.69 BSCF Treib¹⁰ (15.38 wt%)

L 40.40 6.67 25.39 13.04 BSCF Treib¹⁰ (14.49 wt%)

M 39.26 6.49 24.68 15.49 BSCF Treib¹⁰ (14.08 wt%)

N 34.84 5.76 21.90 25.00 BSCF Treib¹⁰ (12.50 wt%) Glass matrix composition

Comp. Si0₂ MgO BaO Bi₂0₃ Membrane material

(wt.%)¹ (wt.%)¹ (wt.%)¹ (wt.%)² (wt.%)²

0 45.33 7.49 28.49 17.89 BSCF Treib^llJ (0.81 wt%)

P 28.49 6.25 35.68 15.49 BSCF Treib^lu (14.08 wt%)

Q 34.65 2.77 32.99 15.49 BSCF Treib^lu (14.08 wt%)

R 39.26 6.49 24.68 15.49 LSCF Treib³ (14.08 wt.%)

The amounts of Si0₂, MgO, and BaO are based on the total weight of the composition.

² The amount of and Bi₂0₃ and membrane material in the composition is based on the total weight of the composition.

³ LSCF Treib: Lao.eSro^Coo^Feo.sO^ Treibacher

⁴ LSFNb: Lao^Sro.sFeo.sNbo^O^ Cerpotech

⁵ LSF: La₀.5Sr₀.5FeO₃_6 Cerpotech

⁶ LSCF Cerp: La₀.6Sro.4Coo.₂Feo.80₃_6 Cerpotech

⁷ LSFZ: La₀.₂Sro.8Feo. ro.i0₃_6 Cerpotech

⁸ CA: cellulose acetate butyrate (Aldrich)

⁹ BSCF Cerp: Bao.₅Sr₀.₅Coo.8Fe₀.₂0₃-5 Cerpotech

¹⁰ BSCF Treib: Bao.sSro.sCoo.sFeo^O^ Treibacher

¹¹ BCFZ Cerp: BaCoo.4Feo.4Zr₀.₂0₃-_6 Cerpotech

Compositions A - R were used in the method for providing a seal between a ceramic component and a substrate according to the invention. Results are described in Example 3.

Example 3: Joining/sealing procedure

The desired amount of glass matrix powder, 5 - 40 wt% of Bi₂0₂ and 1 - 40 wt% of ceramic material (both based on the total weight of the glass matrix powder) were mixed, and ethanol was added in order to create a paste. The paste was applied around the material to be joined, for example BSCF membrane as a ceramic component to YSZ as a substrate. The temperature was raised with 60°C/h to 850°C and kept at this temperature for 2 hours. Subsequently, the temperature was raised with 180°C/h to 1035-1055°C, and kept at this temperature for 30 s to 10 min. The temperature was then lowered with 180°C/h to 900°C, and kept at this temperature for lh. The temperature was then lowered with 60°C/h to 25°C.

Compositions A - R as described above were applied in the method according to the invention for providing a joint between a ceramic component and a substrate, as shown in Table 3.

Table 3: Sealing between a ceramic component and a substrate.

Entry Composition Ceramic component Substrate

1 A La₀.2Sro.8Feo.8Nbo.20₃-6 YSZ¹

3 B La₀.5Sro.5Fe0₃-6 YSZ

5 C Lao.6Sro.4Coo.2Feo.80₃_6 A1₂0₃ ²

7 D Lao.6Sro.4Coo.2Feo.80₃_6 A1₂0₃

9 E Lao.6Sro.4Coo.2Feo.80₃_6 A1₂0₃

1 1 F Lao.2Sro.8Feo. Zro.i0₃_6 A1₂0₃

13 G Bao.5Sro.₅Coo.8Feo.20₃_6 A1₂0₃

15 H Bao.5Sro.₅Coo.8Feo.20₃_6 A1₂0₃

17 I Bao.5Sro.₅Coo.8Feo.20₃_6 A1₂0₃

19 J Bao.5Sro.₅Coo.8Feo.20₃_6 A1₂0₃

20 K Bao.5Sro.₅Coo.8Feo.20₃_6 A1₂0₃

21 L Bao.5Sro.₅Coo.8Feo.20₃_6 YSZ

22 M Bao.5Sro.₅Coo.8Feo.20₃_6 YSZ

23 M Bao.5Sro.₅Coo.8Feo.20₃_6 A1₂0₃

24 M Bao.5Sro.₅Coo.8Feo.20₃_6 Mullite³

25 M Bao.5Sro.₅Coo.8Feo.20₃_6 Crofer⁴

26 M CaTio.₉Feo.i0₃_6 Crofer

27 M CaTio.₉Feo.i0₃_6 Kanthal⁵

28 N Bao.5Sro.₅Coo.8Feo.20₃_6 A1₂0₃

29 O Bao.5Sro.₅Coo.8Feo.20₃_6 A1₂0₃ Entry Composition Ceramic component Substrate

31 P Ba₀.5Sro.5Coo.8Feo.20₃-6 A1₂0₃

32 Q Ba₀.5Sro.5Coo.8Feo.20₃-6 A1₂0₃

33 R Lao.6Sro.4Coo.2Feo.80₃_6 A1₂0₃

YSZ: Yttria stabilized zirconia (3 mol% or 8 mol

Al₂0₃: Aluminium oxide

Mullite: 3Al₂0₃2Si0₂ or 2A1₂0₃ Si0₂

Crofer: Crofer 22 APU, ThyssenKrupp VDM

Kanthal: Kanthal APM, Sandvik

In all cases, the joint between the ceramic component and the substrate has excellent mechanical strength. In addition, in all cases a gastight joint (i.e. a seal) was obtained.

The presence of Bi₂0₃ and a ceramic material in the sealing/joining compositions according to the invention results in an increased wettability on the substrate.

Example 4: Comparison to prior art seals

The seal according to the invention was compared to seals as disclosed in M.J.

Pascual et al, Journal of Power Sources 2007, 169, 40 - 46 (seal 1), and in US 7007509 B2 (seal 2).

Sealing composition 1 (55 mol% Si0₂, 27 mol% BaO, 18 mol% MgO) was prepared as disclosed in M.J. Pascual et al . Sealing composition 2 (67 mol% S1O₂, 25 mol% BaO, 8 mol% MgO) was prepared as disclosed in US 7007509 B2. Both sealing compositions were applied in the sealing of a Bao.₅Sr₀.₅Coo.8Fe₀.₂03-5 ceramic membrane to a YSZ or an Al₂0₃ substrate.

Both with sealing composition 1 and with sealing composition 2 it was complicated to obtain a good wetting of the YSZ substrate and to have a gastight seal.

However, when a sealing/joining composition according to the invention was used, and in the method according to the invention for providing a joint/seal, the presence of Bi₂0₃ and Bao.₅Sr₀.₅Coo.8Fe₀.₂03-5 ceramic material in the sealing/joining compositions increased the wettability on YSZ or AI₂O₃. Moreover, a gastight seal at high temperature was obtained between the membrane and YSZ or AI₂O₃ substrates.

Example 5: Influence of the addition of ceramic-based material

Two sealing compositions were prepared using the same glass matrix composition

(67 mol% Si02, 16.5 mol% MgO, and 16.5 mol% BaO). A first sealing composition (SCI) according to the invention was prepared, comprising 58 wt% of the glass matrix composition, 22 wt% of B1₂O₃, and 20 wt% of ceramic-based material (BSCF). A comparative sealing composition (SC2) was prepared, comprising 78 wt% of the glass matrix composition and 22 wt% of B1₂O₃. Upon heating of the sealing compositions, composition SCI started flowing at 1000°C. Composition SC2 only started flowing at 1050°C, without melting of the glass matrix component. Seals prepared using SCI at temperatures between 1035°C and 1053°C typically were gastight, whereas it was found to be difficult to prepare gastight seals using composition SC2.

Claims

Method for providing a joint between a ceramic component and a substrate, wherein the method comprises the steps of:

(i) providing a composition comprising:

(a) 22 - 55 wt.% Si0₂,

(b) 2 - 15 wt.% MO wherein M is Mg or Zn,

(c) 15 - 48 wt.% BaO,

(d) 2 - 30 wt.% Bi₂0₃,

(e) 0.5 - 25 wt.% ceramic-based material other than (a), (b), (c), and (d), and

(f) optionally, a liquid medium;

The method according to claim 1 , wherein the substrate is selected from the group consisting of a ceramic substrate, a metal substrate, a metal alloy substrate and a combination thereof.

The method according to claim 1 or claim 2, wherein M is Mg.

The method according to any one of claims 1 - 3, wherein the ceramic-based material (e) is a mixed ionic-electronic conducting (MIEC) material.

The method according to any one of claims 1 - 4, wherein in step (iii) the composition is heated to a temperature in the range of 800 - 1350°C.

The method according to any one of claims 1 - 5, wherein the composition comprises: (f) a liquid medium in order to form a paste of the composition.

7. The method according to any one of claims 1 to 6, wherein said composition comprises

(a) 32 - 48 wt.% Si0₂;

(b) 4 - 10 wt.% MO wherein M is Mg or Zn;

(c) 20 - 30 wt.% BaO;

(d) 10 - 23 wt.% Bi₂0₃; and

(e) 3 - 18 wt.% ceramic-based material,

8. The method according to any one of claims 1 to 7, wherein said composition comprises less than 0.5 wt.% B₂0₃.

9. A glass matrix composition comprising:

(A) 62 - 72 mol% Si0₂;

(B) 14 - 19 mol% MO, wherein M is Zn or Mg; and

(C) 14 - 19 mol% BaO;

wherein the amounts of (A), (B) and (C) are based on the total amount of moles Si0₂, MO and BaO present in said glass matrix composition.

10. A composition comprising :

(a) 22 - 55 wt.% Si0₂,

(b) 2 - 15 wt.% MO wherein M is Mg or Zn,

(c) 15 - 48 wt.% BaO,

(d) 2 - 30 wt.% Bi₂0₃,

(f) optionally, a liquid medium in order to form a paste of said composition; wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight of the composition excluding any liquid medium.

11. The composition according to claim 10, wherein the composition is a particulate composition.

12. The composition according to 10 or claim 11, wherein the composition comprises:

(f) a liquid medium,

and wherein the composition is in the form of a paste.

13. The composition according to any one of claims 10 - 12, wherein M is Mg.

14. The composition according to any one of claims 10 - 13, wherein the ceramic- based material is a mixed ionic-electronic conducting (MIEC) material.

15. The composition according to any one of claims 10 to 14, comprising

(a) 32 - 48 wt.% Si0₂;

(b) 4 - 10 wt.% MO wherein M is Mg or Zn;

(c) 20 - 30 wt.% BaO;

(d) 10 - 23 wt.% Bi₂0₃; and

(e) 3 - 18 wt.% ceramic-based material,

wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight of the composition excluding any liquid medium

16. The composition according to any one of claims 10 to 15, wherein said composition comprises less than 0.5 wt.% B₂0₃.

17. Use of a composition according to any one of claims 10 - 16 for providing a joint between a ceramic component and a substrate.

18. A ceramic component and a substrate which are joined via a joint, wherein the joint comprises a composition comprising:

(a) 22 - 55 wt.% Si0₂,

(b) 2 - 15 wt.% MO wherein M is Mg or Zn,

(c) 15 - 48 wt.% BaO,

(d) 2 - 30 wt.% Bi₂0₃, and (e) 0.5 - 25 wt.% ceramic-based material other than (a), (b), (c), and (d);

wherein the amounts in wt.% of (a), (b), (c), (d) and (e) are based on the total weight of the composition.

19. A device, comprising a ceramic component and a substrate which are joined via a joint according to claim 18.

20. The device according to claim 19, which is a catalytic membrane reactor or a solid oxide fuel cell.