Glass-Ceramic Feedthrough Bonding for Thermal Stress Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Temperature-resistant cohesive connections between ceramic and metal alloy elements are challenging due to differing thermal expansion coefficients, leading to mechanical stress and potential cracking, especially in high-temperature applications and miniaturized sensors where materials with fine-grained structures are required.
Innovation Solution
A glass connecting agent with a bismuth content of at least 10% is used, which has a thermal expansion coefficient matching that of the alloy element, allowing for a cohesive connection that adapts the ceramic element's expansion coefficient, reducing mechanical stress and maintaining the connection's integrity up to the glass transition temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a glass bonding agent with high melting temperature (e.g., borosilicate glass above 800°C) is used to create temperature-resistant connections, then the connection's temperature resistance is improved, but the manufacturing cost increases and the manufacturing process becomes more complex
Solution Approach 1:
The patent changes the chemical composition parameters of the glass bonding agent by incorporating specific metal oxides (Bi2O3 at least 10 wt.%, B2O3 at least 5 wt.%, ZnO at least 10 wt.%) to achieve a lower melting point while maintaining temperature resistance. This parameter modification allows bonding at temperatures below 800°C, resolving the contradiction between temperature resistance and manufacturing ease.
2Strength
If elements are joined at high temperatures to create strong bonds, then the bond strength is improved, but mechanical stress increases due to thermal expansion differences, leading to cracking and joint weakening
Solution Approach 1:
The patent modifies the thermal expansion coefficient parameter of the glass bonding agent by adjusting its chemical composition to match that of the alloying element (at least 9×10^-6 K^-1). This parameter matching reduces thermal expansion differences between joined elements, minimizing mechanical stress and preventing cracking while maintaining bond strength.
Solution Approach 2:
The patent creates a composite glass bonding agent with a specific multi-component composition (Bi2O3, B2O3, ZnO, SiO2, Al2O3) that combines the properties of low melting point with matched thermal expansion coefficient. This composite material approach allows the bonding agent to provide both strong bonding and stress reduction simultaneously.
3Ease of manufacture
If the glass bonding agent's melting temperature is lowered to reduce manufacturing complexity, then ease of manufacture is improved, but the connection's temperature resistance deteriorates
Solution Approach 1:
The patent develops a composite glass bonding agent with a specific multi-oxide composition that achieves a synergistic effect: Bi2O3 and B2O3 lower the melting point to below 800°C for easier manufacturing, while the overall composition maintains a thermal expansion coefficient matching the alloying element to ensure temperature resistance. This composite approach resolves the contradiction between manufacturing ease and temperature resistance.
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 temperature-resistant and cost-effective connection that minimizes cracking and maintains the connection's integrity, even under temperature changes, while being suitable for low-temperature manufacturing below 800°C, thus addressing the limitations of existing high-temperature bonding methods.
Implementation Method 1
The glass bonding agent is melted at high temperatures above 800°C during the production of the feedthrough and creates a bonded joint with the elements to be connected. This process is also known in the technical world as 'vitrification.'
Implementation Method 2
The temperature-resistant, material-tight connection between a ceramic element and an alloying element made of a metal alloy, or alloy for short, or a metal often presents a challenge due to different thermal expansion coefficients
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
The invention relates to a compound (1), wherein the compound (1) connects an alloying element (2) to a ceramic element (3); by means of a glass bonding agent (4) which is connected to the alloying element (2) by means of a metallurgical bond (24) and wherein the glass bonding agent (4) is connected to the ceramic element (3) by means of a further metallurgical bond (34); wherein the glass bonding agent (4) is made of a glass with a melting point below 800°C; wherein the glass bonding agent (4) has a coefficient of thermal expansion of at least 9 × 10⁻⁶ K⁻¹; wherein the glass bonding agent (4) has a bismuth content of at least 10%; wherein the alloying element (2) has a coefficient of thermal expansion of at least 9 × 10⁻⁶ K⁻¹; wherein the ceramic element (3) has a coefficient of thermal expansion of at most 8 × 10⁻⁶ K⁻¹;wherein the metallurgical bond (34) of the glass bonding agent (4) with the ceramic element (3) has a mixing region (10); wherein the mixing region (10) is a subregion of the ceramic element (3); and wherein the mixing region (10) has a higher proportion of bismuth than the ceramic element (3) outside the mixing region (10).