Expanded Graphite Sheet Low Ash High Flexibility
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Expanded graphite sheets with high ash content can cause damage to mating materials and form defects when used as packings or gaskets, and refining processes to reduce ash content compromise flexibility, leading to cracks and chipping during molding.
Innovation Solution
An expanded graphite sheet with a flexibility of 25 times or greater and ash content of 500 ppm or lower is achieved by using a graphite material with an ash content of 0.1 weight % or lower, treated with a sulfuric acid solution, followed by neutralization, expansion, and compression, without a halogen gas refining process, allowing sulfur to remain and reducing ash content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an expanded graphite sheet is refined using a halogen gas atmosphere at 800°C or higher to reduce ash content, then the ash content is reduced, but the flexibility is lowered
Solution Approach 1:
The invention changes the chemical composition parameters by controlling sulfur content at 500 ppm or higher while maintaining ash content at 500 ppm or lower. This specific parameter combination allows the graphite sheet to achieve both low ash content and high flexibility (25 times or greater), resolving the contradiction between refinement and flexibility preservation
Solution Approach 2:
The invention creates a composite structure within the graphite sheet by maintaining sulfur compounds alongside the graphite base material. The sulfur acts as a flexible binder that holds the expanded graphite structure together, preventing cracks and chipping while allowing the ash content to be reduced through selective removal of metal impurities
2Ease of manufacture
If the ash content in expanded graphite sheet is high, then the material is easier to produce, but mating materials such as metal are damaged
Solution Approach 1:
The invention selectively extracts harmful metal impurities (ash) from the graphite sheet while preserving the beneficial sulfur compounds. By removing only the harmful components (metal particles causing damage) and retaining the useful components (sulfur providing flexibility), the sheet achieves low ash content (500 ppm or lower) without compromising manufacturing simplicity
3Manufacturing precision
If the flexibility of expanded graphite sheet is reduced through refining, then the ash content is reduced, but cracks or chipping occur during molding
Solution Approach 1:
The invention provides beforehand cushioning by maintaining sulfur compounds in the graphite structure prior to molding. This sulfur network acts as a cushioning matrix that prevents crack propagation and chipping during the molding process, even when ash content is reduced to 500 ppm or lower. The sulfur provides structural integrity that compensates for the reduced flexibility from refinement
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 inhibits flexibility degradation, preventing cracks and chipping, thereby enhancing the quality and yield rate of molded products while maintaining reduced ash content.
Implementation Method 1
Natural graphite, pyrolytic graphite, kish graphite, or the like is treated with a mixture solution of sulfuric acid, nitric acid, or the like
Implementation Method 2
the resultant material is subjected to an expansion process in an expansion furnace at about 1000° C.
Data Source
AI summary
An expanded graphite sheet is provided that can remarkably improve the quality and yield rate by preventing chipping and cracks in the surface in molding the sheet into a desired shape by inhibiting degradation in the flexibility while reducing the ash content to a certain degree. An expanded graphite sheet (3) has a flexibility of 25 times or greater, as determined in a flexibility test in which the flexibility is defined as the number of times the expanded graphite sheet (3) can be bent using a flexibility testing device having a rotator (2) to which one end of a plate-shaped expanded graphite sheet (3) is fixed, a weight (7) fixed to the other end of the expanded graphite sheet (3), and a bending position determining member (5) for determining a bending position of the expanded graphite sheet (3) when the rotator (2) is rotated.