Fibrous Ceramic Gasket Sag Resistance
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Solution Overview
Problem
Conventional ceramic gaskets used in high temperature applications, such as Molten Carbonate Fuel Cells, suffer from low compressive strength, sagging issues, and high electrolyte absorption, leading to electrolyte migration and performance degradation.
Innovation Solution
A fibrous ceramic material with entangled fibers connected by heat-treated connectors, featuring a smooth outer surface and improved mechanical properties, is developed to reduce sagging and electrolyte absorption, enhancing compressive strength and sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional ceramic gaskets are used for high temperature sealing, then sealing function is provided, but compressive strength is low and sagging occurs
Solution Approach 1:
The patent uses a composite structure consisting of ceramic fibers embedded in a metal matrix (such as stainless steel, Inconel, or Hastelloy). This composite material combines the high temperature resistance and sealing properties of ceramics with the mechanical strength and sag resistance of metals, resolving the contradiction between providing sealing function and maintaining structural integrity under compressive loads.
2Temperature
If conventional ceramic gaskets are used, then high temperature resistance is achieved, but electrolyte absorption is high leading to migration
Solution Approach 1:
The metal matrix composite structure provides a non-absorbent barrier that prevents electrolyte penetration while maintaining high temperature resistance. The ceramic fibers provide thermal stability and the metal matrix prevents electrolyte absorption, simultaneously achieving both high temperature resistance and low electrolyte absorption.
3Strength
If ceramic fabric is heat treated to improve mechanical properties, then strength increases, but fabric reacts with or sticks to the support
Solution Approach 1:
The patent introduces a metal matrix as an intermediary material between the ceramic fibers and the support structure. This metal matrix allows the ceramic fabric to be heat treated to improve mechanical properties without direct contact and reaction with the support, preventing sticking and chemical reactions while achieving the desired strength enhancement.
4Reliability
If conventional gaskets are compressed for sealing, then sealing contact is achieved, but gasket is crushed irreversibly
Solution Approach 1:
The metal matrix provides high compressive strength and elastic recovery properties, allowing the gasket to be compressed for sealing contact and then recover its shape. The ceramic fibers maintain structural integrity during compression, preventing irreversible crushing while achieving reliable sealing contact under compressive loads.
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 fibrous ceramic material exhibits improved sag resistance, reduced electrolyte absorption, and lower electrolyte migration rates, maintaining sealing integrity under compressive loads and extending the life of fuel cell stacks.
Implementation Method 1
The grain size of the fibers is at least 5μm (micrometers) to form a generally smooth outer surface thereby reducing wettability and liquid absorption compared to a finer-grain structure, with a rougher fiber surface having a high wettability and high liquid absorption.
Implementation Method 2
a portion of which are joined by connectors formed as a result of heat treating a precursor material
Data Source
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AI summary
A fibrous ceramic material including a plurality of fibers entangled with one another. The fibrous ceramic material includes at least one connector projecting between the fibers. At least a portion of the fibers have the connectors extending between and attach the fibers to one another. A method of manufacturing the fibrous ceramic material includes providing a precursor material having a plurality of fibers. A holder is provided for holding the precursor material. The precursor material is placed on the holder and both are heated to between about 1500 degrees Celsius and about 1700 degrees Celsius to form the fibrous ceramic material, thereby causing connectors to project from a portion of the fibers and attach the fibers to one another.