Glass-Ceramic Seal Composition for High-Temperature Joints
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Solution Overview
Problem
Current glass compositions for high-temperature applications, such as high-temperature electrolyzers and fuel cells, face challenges in achieving a suitable coefficient of thermal expansion and mechanical strength while minimizing interactions with ceramic and metal substrates, leading to issues like corrosion and evaporation at high temperatures.
Innovation Solution
A glass-ceramic composition comprising SiO2, Al2O3, and CaO, with additional oxides like ZnO, MnO2, B2O3, and TiO2, that transforms from an amorphous to a vitrocrystalline state upon heat treatment, forming strong bonds with minimal interaction with substrates and maintaining mechanical integrity under thermal cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass compositions are used for high-temperature seals, then sealing function is achieved, but chemical interactions with substrates cause corrosion and evaporation
Solution Approach 1:
The patent modifies the chemical composition parameters of the glass by incorporating specific oxide ratios (SiO2: 30-70%, Al2O3: 10-40%, CaO: 5-20%, and additional oxides totaling 5-20%) to achieve optimal chemical stability. This compositional parameter optimization reduces harmful chemical interactions with metal and ceramic substrates while maintaining effective sealing performance at high temperatures
Solution Approach 2:
The patent creates a composite glass-ceramic material system that combines multiple oxide components to form a chemically resistant seal. The composite structure includes silicate, aluminate, and calcium oxide phases that work synergistically to provide both sealing functionality and resistance against corrosion and evaporation at operating temperatures up to 1000°C
2Reliability
If glass compositions are used for high-temperature seals, then sealing is achieved, but suitable coefficient of thermal expansion is difficult to obtain
Solution Approach 1:
The patent adjusts the thermal expansion characteristics by modifying the glass composition parameters, particularly the ratios of Al2O3 (10-40%) and CaO (5-20%), which directly influence the coefficient of thermal expansion. This enables the seal to accommodate thermal expansion differences between dissimilar substrates (metal-ceramic, ceramic-ceramic, metal-metal) while maintaining seal integrity during thermal cycling
Solution Approach 2:
The patent develops a universal glass-ceramic composition that can serve as a seal material for multiple substrate combinations (metal-metal, metal-ceramic, ceramic-ceramic) with different thermal expansion coefficients. The multi-functional formulation provides both sealing and thermal expansion accommodation across diverse application scenarios
3Ease of manufacture
If glass compositions are used for high-temperature seals, then assembly is achieved, but mechanical strength is insufficient under thermal cycles
Solution Approach 1:
The patent utilizes the phase transition from amorphous glass to crystalline glass-ceramic through controlled heat treatment. The material is first applied in a glassy state for easy assembly, then undergoes crystallization at elevated temperatures to develop enhanced mechanical strength and structural stability, achieving both ease of manufacture and high strength properties
Solution Approach 2:
The patent applies the glass composition in a pre-processed glassy state that facilitates easy assembly and bonding to substrates before thermal treatment. The preliminary glass application step enables simple manufacturing and assembly, followed by in-situ crystallization that strengthens the joint without requiring separate processing steps
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 composition provides a chemically and mechanically resistant seal with a high coefficient of thermal expansion, accommodating diverse substrate materials and reducing interactions, thus ensuring reliable and stable performance under high-temperature conditions.
Implementation Method 1
A glass-ceramic composition comprising SiO2, Al2O3, and CaO, with additional oxides like ZnO, MnO2, B2O3, and TiO2, that transforms from an amorphous to a vitrocrystalline state upon heat treatment
Implementation Method 2
The composition provides a chemically and mechanically resistant seal with a high coefficient of thermal expansion, accommodating diverse substrate materials
Data Source
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AI summary
The invention relates to a glass-ceramic composition consisting of Si02, A1203, and CaO, or of Si02, A1203, CaO and SrO, or of Si02, A1203 et La203. The invention also relates to a method and the assembly of at least two parts using said composition, and to the joint and assembly obtained by said method. The invention further relates to a high-temperature electrolyser (EHT) or a solid oxide fuel cell comprising said joint or said assembly.