Glass Composite Seal for Solid Oxide Fuel Cell
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing solid oxide fuel cell (SOFC) stack seals, such as G-18 glass, crystallize and become hard and brittle at elevated operating temperatures, losing their ability to maintain a hermetic seal and fill gaps, necessitating a seal material that remains compliant and self-healing over time.
Innovation Solution
A glass composite seal comprising alkaline earth aluminosilicate (AEAS) glass and viscous glass, optionally with additives like zirconium oxide, aluminum oxide, or yttria-stabilized zirconia, which maintains structural integrity and allows for self-healing by retaining viscous glass between sealing surfaces, ensuring a compliant and robust seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If G-18 glass is used for sealing at high temperatures, then high electrical resistivity and chemical stability are achieved, but the glass crystallizes and becomes hard and brittle, losing sealing ability
Solution Approach 1:
The patent uses a composite glass seal comprising G-18 glass combined with other glass components to create a material that maintains both high temperature stability and sealing ability. The composite structure prevents complete crystallization while retaining the desirable properties of G-18 glass.
Solution Approach 2:
The patent modifies the glass composition parameters by adding specific components to G-18 glass, changing its crystallization behavior and maintaining amorphous structure at operating temperatures, thereby preventing brittleness while preserving chemical stability.
2Temperature
If G-18 glass is used for sealing, then high coefficient of thermal expansion is achieved, but the glass becomes brittle and loses ability to fill gaps over time
Solution Approach 1:
The composite glass seal combines G-18 glass with additional components that maintain flexibility and gap-filling ability even at high temperatures. The composite structure allows the seal to expand thermally while retaining the ductility needed to fill sealing surface gaps.
3Reliability
If a single glass material is used for sealing, then manufacturing simplicity is maintained, but the seal cannot maintain hermeticity over prolonged elevated temperatures
Solution Approach 1:
The patent employs a composite glass material that integrates multiple components into a single seal structure. This composite approach maintains hermeticity over time at elevated temperatures while being applied as a unified seal material, balancing performance with practical application simplicity.
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 glass composite seal provides a durable, self-healing hermetic seal that maintains performance over prolonged elevated temperatures and repeated thermal cycling, ensuring the longevity and efficiency of the SOFC stack.
Implementation Method 1
a viscous glass such that the AEAS glass retains the viscous glass in a predetermined position between the sealing surfaces
Implementation Method 2
a coefficient of thermal expansion comparable to those of the components of the SOFC stacks
Data Source
AI summary
A solid oxide fuel cell stack having a plurality of cassettes and a glass composite seal disposed between the sealing surfaces of adjacent cassettes, thereby joining the cassettes and providing a hermetic seal therebetween. The glass composite seal includes an alkaline earth aluminosilicate (AEAS) glass disposed about a viscous glass such that the AEAS glass retains the viscous glass in a predetermined position between the first and second sealing surfaces. The AEAS glass provides geometric stability to the glass composite seal to maintain the proper distance between the adjacent cassettes while the viscous glass provides for a compliant and self-healing seal. The glass composite seal may include fibers, powders, and/or beads of zirconium oxide, aluminum oxide, yttria-stabilized zirconia (YSZ), or mixtures thereof, to enhance the desirable properties of the glass composite seal.