Carbon Substrate Thickness Control via Oxidized Fiber Preweb and Rolling Curing
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Solution Overview
Problem
Conventional methods for preparing carbon substrates for gas diffusion layers in PEFCs face issues such as thickness deviations, low processability, and non-uniform curing, leading to difficulties in controlling resin impregnation and maintaining uniform thickness, due to the use of unoxidized carbon precursor fibers and non-continuous curing processes.
Innovation Solution
A method using oxidized carbon precursor staple fibers and binder staple fibers, skipping the oxidation treatment, and employing a multi-step rolling curing process with two or more press roll units to continuously form and cure the carbon substrate, ensuring uniform thickness and enhanced productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If unoxidized carbon precursor staple fibers are used with conventional curing process, then the oxidation treatment step can be included in the process, but thickness deviations occur and processability is reduced
Solution Approach 1:
The carbon precursor staple fibers are pre-oxidized before being incorporated into the web structure. This preliminary oxidation treatment modifies the fiber surface properties in advance, enabling subsequent uniform resin impregnation and curing without requiring additional oxidation steps during the manufacturing process, thereby achieving thickness uniformity while maintaining process simplicity
Solution Approach 2:
The oxidation state of the carbon precursor fibers is changed as a key parameter before web formation. By controlling the oxidation degree and timing, the fiber surface characteristics are optimized for resin bonding, which directly improves thickness uniformity during curing while avoiding the need for complex multi-step processes
2Manufacturing precision
If non-continuous curing process is used, then the process flexibility is maintained, but resin impregnation uniformity and thickness control are compromised
Solution Approach 1:
The curing process is transformed from a non-continuous batch operation to a continuous process where the carbon fiber web passes through heated rollers that maintain consistent temperature and pressure conditions. This continuous action ensures uniform resin impregnation throughout the web while significantly increasing production efficiency through uninterrupted manufacturing
Solution Approach 2:
The conventional mechanical pressing and batch heating method is replaced with a roller-based system that combines thermal and mechanical compression in a continuous flow. The heated rollers provide both the thermal energy for curing and the mechanical pressure for resin distribution, achieving uniform impregnation while enabling continuous high-speed production
3Ease of operation
If conventional pressing method is used, then the equipment simplicity is maintained, but workability and thickness uniformity are reduced
Solution Approach 1:
Flat pressing surfaces are replaced with curved roller surfaces that conform to the web geometry during compression. The cylindrical shape of the rollers provides uniform pressure distribution across the web width and maintains consistent gap thickness, dramatically improving thickness control while the continuous rotation mechanism enhances operational ease compared to manual or mechanical pressing systems
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
This approach results in a carbon substrate with reduced thickness deviations, improved mechanical strength, and enhanced workability, allowing for uniform resin impregnation and continuous production, thereby addressing the limitations of conventional technologies.
Implementation Method 1
a curing process for applying heat and pressure to the oxidized carbon precursor fiber web, which has been impregnated with the thermosetting resin and the carbonaceous fillers, to cure the thermosetting resin
Implementation Method 2
a multi-step rolling curing process by two or more press roll units
Implementation Method 3
a carbonization process for heating the oxidized carbon precursor fiber web in an inert atmosphere, thereby carbonizing the oxidized carbon precursor staple fibers
Data Source
AI summary
A carbon substrate, method, and a system for manufacturing the same. The method includes forming an oxidized carbon precursor fiber preweb comprising oxidized carbon precursor staple fibers and binder staple fibers; impregnating the oxidized carbon precursor fiber preweb with a slurry including a thermosetting resin and carbonaceous fillers and drying the resulting preweb to obtain an oxidized carbon precursor fiber web; applying heat and pressure to the oxidized and impregnated carbon precursor fiber web, to cure the thermosetting resin and press the oxidized carbon precursor fiber web; and heating the oxidized carbon precursor fiber web in an inert atmosphere, thereby stabilizing and carbonizing the oxidized carbon precursor staple fibers to obtain a carbon substrate. The present invention may utilize a combination of carbon precursor staple fibers in an oxidized form with low ductility and high stiffness; and binder staple fibers composed of a polymer resin.