Glass Seal with Deformable Phase for SOFC Dimensional Tolerance
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Solution Overview
Problem
Solid oxide fuel cell stacks face challenges in sealing due to lack of dimensional flatness and parallelism, requiring seals that are chemically and mechanically stable at high temperatures, non-conductive, and compatible with cell materials, while maintaining low fuel leakage and long service life, which existing technologies fail to address effectively.
Innovation Solution
A seal comprising a glass matrix with a deformable second phase material dispersed within, having a glass transition temperature below 650°C, and a coefficient of thermal expansion matching the electrolyte, which accommodates dimensional irregularities and ensures self-healing properties, low permeability, and compatibility with fuel cell components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing seal materials are used, then chemical and mechanical stability at high temperature can be achieved, but dimensional flatness and parallelism irregularities cannot be accommodated
Solution Approach 1:
The seal material's physical properties are changed by controlling the glass transition temperature to be below 650°C, allowing the material to transition from a rigid state during manufacturing to a more compliant state during operation, enabling it to accommodate dimensional irregularities while maintaining stability
Solution Approach 2:
The invention uses a composite glass matrix containing dispersed second-phase particles (such as zirconium oxide hollow spheres or silicate fibers). This composite structure combines the chemical stability of glass with the deformability of the second phase, allowing simultaneous achievement of reliability and adaptability to dimensional variations
2Adaptability or versatility
If seal material is made more compliant to accommodate dimensional variations, then manufacturing precision tolerance increases, but electrical conductivity may increase
Solution Approach 1:
The seal material exhibits different properties in different phases: the glass matrix provides electrical insulation and chemical stability, while the dispersed second-phase particles provide compliance and deformability. This local differentiation allows the material to be compliant without becoming conductive
3Duration of action of stationary object
If service life is extended to exceed 40,000 hours, then durability increases, but fuel leakage risk increases due to thermal cycling
Solution Approach 1:
The glass matrix is designed with a glass transition temperature below 650°C to act as a cushioning mechanism that activates during thermal cycling. This allows the seal to undergo controlled softening and self-healing during operation, preventing crack propagation and fuel leakage before they can occur
Solution Approach 2:
The seal material performs self-healing during thermal cycles through the glass transition mechanism. The material automatically adjusts its properties in response to temperature changes, sealing micro-defects without external intervention and maintaining fuel leakage prevention over extended service life
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 solution provides a seal with a fuel leakage rate less than 1% and a service life exceeding 40,000 hours, accommodating dimensional variations and ensuring reliable operation across thermal cycles, thus enhancing the scalability and commercial viability of solid oxide fuel cell technology.
Implementation Method 1
The glass matrix can have a coefficient of thermal expansion within 20% of the coefficient of thermal expansion of the electrolyte
Implementation Method 2
The glass matrix can have an electrical resistivity of greater than 104 Ohm cm
Implementation Method 3
Pressure is applied to the seal precursor such that the second phase material undergoes a deformation of at least 10%
Implementation Method 4
A seal for a solid oxide fuel cell comprises a glass matrix having glass percolation therethrough and having a glass transition temperature below 650° C.
Data Source
AI summary
A seal for a solid oxide fuel cell includes a glass matrix having glass percolation therethrough and having a glass transition temperature below 650° C. A deformable second phase material is dispersed in the glass matrix. The second phase material can be a compliant material. The second phase material can be a crushable material. A solid oxide fuel cell, a precursor for forming a seal for a solid oxide fuel cell, and a method of making a seal for a solid oxide fuel cell are also disclosed.