Metal Seal With Ceramic Core for High-Temperature Electrolysis
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Solution Overview
Problem
Current seals for high-temperature electrochemical cells, such as those in high temperature steam electrolyzers and SOFC fuel cells, fail to provide a reliable, electrically insulating, and corrosion-resistant seal that accommodates thermal expansion differences between metal and ceramic materials, while also being easily removable and recyclable.
Innovation Solution
A seal comprising a central electrically insulating layer with adaptable thickness, surrounded by metal layers with patterned surfaces for intimate contact and binder layers made of vitreous or glass-ceramic materials to absorb thermal expansion and maintain a secure seal without excessive compression, allowing for easy assembly and disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal seal is used to accommodate thermal expansion differences between metal and ceramic materials, then the seal can withstand shear stress during thermal transients, but the seal conducts electricity and cannot be installed between the two interconnectors of a high temperature steam electrolyser
Solution Approach 1:
The seal is divided into three distinct layers: an outer metal layer for shear stress resistance, an intermediate vitreous or glass-ceramic layer for electrical insulation, and an inner metal layer for bonding to ceramic surfaces. This segmentation allows each layer to perform its specific function without compromising the others.
Solution Approach 2:
The seal combines multiple materials with different properties into a composite structure: metal provides mechanical strength and shear resistance, while vitreous or glass-ceramic materials provide electrical insulation and chemical inertness. This composite approach resolves the contradiction between requiring electrical insulation and accommodating thermal expansion.
2Reliability
If vitreous or glass-ceramic material is used for the seal, then the seal provides electrical insulation and chemical inertness, but the seal adheres strongly to surfaces and leads to cell breakage when the electrolyser is opened for maintenance
Solution Approach 1:
The vitreous or glass-ceramic layer is segmented and positioned between metal layers that provide mechanical strength. This segmentation prevents the glass-ceramic from directly bonding to both metal surfaces simultaneously, reducing adhesion strength and facilitating disassembly.
Solution Approach 2:
Different layers of the seal have different bonding characteristics: the metal layers are designed for strong bonding to ceramic surfaces, while the vitreous or glass-ceramic layer has controlled adhesion properties that allow for easier removal. This local differentiation of bonding strength resolves the contradiction between maintaining seal integrity and enabling disassembly.
3Strength
If ductile materials are used for the seal to resist shearing, then the seal can withstand thermal expansion, but the materials risk exhibiting insufficient sealing properties
Solution Approach 1:
The seal is segmented into metal layers for shear resistance and vitreous or glass-ceramic layers for sealing properties. This segmentation allows ductile metal to handle thermal expansion while the glass-ceramic material provides the necessary sealing characteristics.
Solution Approach 2:
The composite structure combines ductile metal with brittle but sealing-effective vitreous or glass-ceramic materials. The metal provides shear resistance and flexibility, while the glass-ceramic provides sealing properties and electrical insulation, resolving the contradiction between shear resistance and sealing effectiveness.
4Ease of manufacture
If common seal materials are used at high temperatures, then the seal can be manufactured easily, but the materials deteriorate at high temperatures, losing their initial properties and often not being electrically insulating
Solution Approach 1:
The seal uses a composite of metal and vitreous or glass-ceramic materials, each selected for their high temperature stability and complementary properties. The glass-ceramic component specifically provides electrical insulation and resistance to deterioration at high temperatures, while the metal provides structural integrity.
Solution Approach 2:
The seal materials are selected and designed to maintain their physical and chemical properties at high operating temperatures. The vitreous or glass-ceramic layer specifically undergoes parameter changes that enhance its electrical insulation properties at elevated temperatures while resisting chemical corrosion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The seal effectively maintains a tight seal at high temperatures (up to 800°C) with low gas permeability and chemical inertness, while being easily removable and recyclable, addressing the limitations of existing materials that are mechanically fragile, conductive, or prone to corrosion.
Implementation Method 1
the binder layer being made of vitreous or glass-ceramic material at the temperature of use
Implementation Method 2
an outer metallic layer provided with a pattern for attaching to a surface to be sealed, and a binder layer between the outer layer and the central layer, the binder layer being made of vitreous or glass-ceramic material
Implementation Method 3
an outer metallic layer provided with a pattern for attaching to a surface to be sealed
Data Source
AI summary
The invention relates to a seal, including a central layer (5) made of an electrically insulating material, two metal outer layers (6, 7), having patterns (8, 9) capable of deforming by being flattened against the bearing surfaces (2, 3) to be sealed so as to maintain the seal while providing a sealing barrier at the connections, and intermediate layers (10, 11) made of a vitreous material in order to ensure the connection to the preceding layers while absorbing the deformations resulting from the differential expansions. The invention can be used in high-temperature electrolysis or in fuel cells.