Composite Encapsulating Material for SOFC Thermal Stress
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Solution Overview
Problem
Existing high-temperature Solid Oxide Fuel Cell (SOFC) encapsulation materials face issues with stress-induced damage due to thermal expansion and chemical reactions, leading to poor heat stability and air impermeability, particularly when using boron and alkaline earth elements which result in material degradation and environmental pollution.
Innovation Solution
A composite encapsulating material comprising silicon dioxide, aluminum oxide, and zinc oxide, with a glass transition temperature between 694° C. and 833° C., and an expansion coefficient between 7.0 and 8.5×10−6/° C., along with the addition of bismuth yttrium oxide as a glass additive to enhance air impermeability and thermal expansion matching, eliminating the use of lead, boron, and alkaline earth elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If boron oxide is added to glass to lower melting point and increase wettability, then ease of manufacture is improved, but heat stability deteriorates due to generation of boron hydroxide and material degradation
Solution Approach 1:
The patent removes boron oxide from the glass composition entirely, replacing it with zinc oxide and adjusting the ratios of silicon dioxide, aluminum oxide, and other oxides to achieve the desired wettability and melting characteristics without the harmful effects of boron hydroxide generation
Solution Approach 2:
The patent changes the chemical composition parameters by eliminating boron oxide and optimizing the ratios of alternative oxides (silicon dioxide: 3.53-6.97 mol%, aluminum oxide: 8.39-17.78 mol%, zinc oxide: 11.11-47.64 mol%) to maintain manufacturability while improving heat stability
2Ease of manufacture
If alkaline earth elements (barium, calcium, magnesium) are used in glass composition, then ease of manufacture is improved, but chemical reactions occur that deteriorate resistivity of SOFC and cause breaks between composite materials
Solution Approach 1:
The patent completely eliminates alkaline earth elements (barium oxide, calcium oxide, magnesium oxide) from the glass composition, replacing them with zinc oxide and optimized combinations of silicon dioxide and aluminum oxide to prevent chemical reactions that would degrade SOFC performance
Solution Approach 2:
The patent creates a composite glass material using a specific combination of oxides (silicon dioxide, aluminum oxide, zinc oxide, and other compatible oxides) that provides both manufacturability and chemical stability, avoiding the harmful interactions of alkaline earth elements with SOFC components
3Adaptability or versatility
If glass transition temperature is adjusted to 600-800°C for SOFC operating temperature, then adaptability is improved, but stress-induced damage occurs due to thermal expansion and contraction cycles
Solution Approach 1:
The patent optimizes the glass transition temperature within the 600-800°C range by carefully controlling the composition ratios of zinc oxide (11.11-47.64 mol%), aluminum oxide (8.39-17.78 mol%), and silicon dioxide (3.53-6.97 mol%), while the resulting expansion coefficient (7.0-8.5×10−6/°C.) provides stress resistance through better thermal expansion matching with SOFC components
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 improved air impermeability, lower softening temperature, easier compression, and reduced thermal expansion mismatch, enhancing the durability and environmental sustainability of SOFC encapsulation while maintaining effective heat stability and resistance to chemical reactions.
Implementation Method 1
glass transition temperature should be adjusted in the range of 600° C. ̃800° C., operating temperature of SOFC
Implementation Method 2
matching attribute and heat stability are critical. Accordingly, an encapsulating material should be effective in a buffer action to reduce any stress-induced damage to one component out of expansion and contraction
Data Source
AI summary
The present invention is a composite encapsulating material which consists of silicon dioxide, aluminum oxide, yttrium oxide and zinc oxide and has glass transition temperature between 694° C. and 833° C. as well as expansion coefficient between 7.0 and 8.5×10−6/° C. The ratio of the number of moles of silicon dioxide plus aluminum oxide (yttrium oxide or zinc oxide) to the total number of moles is 41.88˜62.22% (10.48˜26.67% or 11.11˜47.64%); the ratio of the number of moles of aluminum oxide to the total number of moles is 5.23˜17.78%. The ratios of aluminum oxide to silicon dioxide, yttrium oxide to silicon dioxide, and zinc oxide to silicon dioxide are 0.14˜0.40, 0.29˜0.60, and 0.25˜1.30, respectively.