Ceramic Filter Glass Seal Thermal Expansion Mismatch
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Solution Overview
Problem
Ceramic filters used at high temperatures and in alkaline aqueous solutions often experience cracks at the end-part glass sealing portion, particularly when a zeolite separation membrane is involved, due to thermal stress and differences in thermal expansion coefficients between the glass seal and the porous substrate.
Innovation Solution
Incorporating inorganic particles made of clay into the glass seal, with a thermal expansion coefficient ratio of 90% or less compared to the porous substrate, to alleviate thermal stress and prevent cracking, while maintaining effective sealing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional glass seal is used at high temperatures, then sealing properties are maintained, but cracks occur at the end-part glass sealing portion due to thermal stress and thermal expansion mismatch
Solution Approach 1:
The invention modifies the thermal expansion coefficient parameter of the glass seal by incorporating specific inorganic particles (alumina, silica, zirconia) to match the porous substrate's thermal expansion characteristics. This parameter adjustment reduces thermal stress during temperature changes, preventing crack formation while maintaining sealing effectiveness at high temperatures
Solution Approach 2:
The glass seal is formulated as a composite material containing glass matrix with dispersed inorganic particles (alumina, silica, zirconia). This composite structure combines the sealing properties of glass with the thermal stability and controlled thermal expansion of the inorganic particles, resolving the contradiction between temperature resistance and crack resistance
2Ease of manufacture
If the thermal expansion coefficient ratio between glass seal and porous substrate is not controlled, then manufacturing is simpler, but thermal stress causes cracking during high-temperature use
Solution Approach 1:
The invention establishes a specific parameter range for the thermal expansion coefficient ratio (0.95-1.05) to minimize thermal stress. By controlling this parameter through selective addition of inorganic particles to the glass seal, the patent achieves thermal compatibility with the porous substrate while maintaining practical manufacturability
Solution Approach 2:
The inorganic particles (alumina, silica, zirconia) act as intermediary materials between the glass seal and porous substrate. These particles mediate the thermal expansion mismatch by providing a transitional thermal expansion coefficient that bridges the gap between glass and ceramic materials, reducing interfacial thermal stress
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 ceramic filter can be used for extended periods at high temperatures without cracking, ensuring reliable filtration performance and improved heat resistance and sealing properties, even in large honeycomb shapes.
Implementation Method 1
a ratio of a coefficient of thermal expansion of the glass seal to a coefficient of thermal expansion of the porous substrate is 90% or less
Data Source
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AI summary
Provided is a ceramic filter that can be used for a long time at a high temperature, including a porous substrate having a partition wall that defines and forms a cell extending from one end face to the other end face, the porous substrate being made of ceramic a separation membrane disposed on a wall face in the cell; and glass seal disposed at the one end face and the other end face so as not to block open frontal areas of the cell. The glass seal includes glass and inorganic particles dispersed in the glass, the inorganic particles being made of clay, and a ratio of a coefficient of thermal expansion of the glass seal to a coefficient of thermal expansion of the porous substrate is 90% or less.