Fuel Cell Stack Sealing Arrangement with Ceramic Insulating Layer
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Solution Overview
Problem
Current sealing systems for fuel cell stacks face challenges in achieving long-term stability under mechanical stress during thermocycling due to poor thermal conductivity and brittleness in glass solder seals, and high material consumption and residual stresses in metal solder seals with additional insulating layers.
Innovation Solution
A method involving the production of a dense, electrically insulating ceramic layer using cost-effective wet-chemical routes like screen printing or dispensing, with sintering processes that include additives to lower melting temperatures and match thermal expansion coefficients, and optional metallic soldering for ductility, to create a stable sealing arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass solder seals are used for sealing, then good gas tightness and electrical insulation are achieved, but tolerance to mechanical stress during thermocycling is poor
Solution Approach 1:
The sealing arrangement uses a composite structure combining glass solder material (for gas tightness and electrical insulation) with a metal solder layer (for mechanical stress tolerance). The glass solder forms the primary sealing layer while the metal solder layer provides ductility to accommodate thermal expansion differences during thermocycling, resolving the contradiction between insulation performance and mechanical tolerance.
Solution Approach 2:
The invention changes the material parameters by introducing a metal solder layer with different mechanical properties (higher ductility, different thermal expansion coefficient) adjacent to the glass solder seal. This parameter change allows the sealing system to maintain both the electrical insulation properties of glass solder and the mechanical flexibility needed for thermocycling tolerance.
2Strength
If metal solder seals with additional insulating layer are used, then ductile behavior during thermal cycling is improved, but material consumption and manufacturing complexity increase
Solution Approach 1:
The invention merges the sealing function and insulation function into a single integrated glass solder seal structure, eliminating the need for separate metal solder seals and additional insulating layers. The glass solder material itself provides both the sealing function and electrical insulation, while the integrated design reduces manufacturing steps and material consumption compared to multi-layer approaches.
Solution Approach 2:
The glass solder seal is designed to perform multiple functions simultaneously: it provides gas tightness, electrical insulation, and through its composition and structure, accommodates thermal expansion. This multi-functionality reduces the need for additional specialized components, thereby simplifying the overall device structure and reducing material consumption.
3Reliability
If thicker insulating layer of aluminum-magnesium spinel is used, then electrical insulation is improved, but residual stresses and risk of cracks increase
Solution Approach 1:
The invention changes the material parameters by using glass solder material with thermal expansion coefficients matched to the adjacent metal components. This parameter matching reduces thermal stress during temperature cycles, allowing for adequate electrical insulation without requiring excessively thick layers that would generate harmful residual stresses and cracks.
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 method produces a sealing arrangement with excellent gas tightness and electrical insulation, capable of withstanding thermal cycling while minimizing material consumption and residual stresses, ensuring long-term stability and reduced risk of leaks.
Implementation Method 1
Heating of the two components (102, 104) and the coating made from the insulating layer precursor material arranged between them to a sintering temperature to produce the sintered, electrically insulating, ceramic insulating layer (106)
Implementation Method 2
the insulating layer pre-material contains an additive for lowering the melting temperature of the insulating layer
Implementation Method 3
By adding MgO, the coefficient of thermal expansion of the insulation layer can be adapted to the coefficient of thermal expansion of other elements of the fuel cell stack
Data Source
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AI summary
The invention relates to a method for producing an electrically insulating sealing arrangement for sealing two components (102, 104) of a fuel cell stack off from each other. The method according to the invention comprises the following steps: applying a starting material for the insulating layer to a substrate in a wet-chemical process; heating the starting material for the insulating layer to a sinter temperature to produce a sintered, electrically insulating, ceramic insulating layer; directly or indirectly connecting the insulating layer (106) to the components (102, 104) to be sealed from each other. The method according to the invention allows production of a sealing arrangement which has a long-term stability when operating in a fuel cell system, a good gas tightness and good electrical insulation properties.