Polyamide Graphite Composite for Cryogenic Tank Liners
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Solution Overview
Problem
Current cryogenic liquid storage and transportation technologies, particularly for liquid oxygen, face challenges due to high density, cost, and compatibility issues with metallic alloys, which hinder mass reduction and safety in space launchers, and existing composite materials lack LOX compatibility and permeability standards.
Innovation Solution
A composite material comprising 60-90% polyamide 6, 10-30% primary synthetic graphite, and 0-10% antioxidant agent, specifically designed to meet LOX compatibility, low density, and helium impermeability standards, suitable for use in cryogenic tanks and liquid oxygen storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metallic alloys are used to make cryogenic tanks, then mechanical strength and structural integrity are ensured, but density is high which increases the mass of space launchers
Solution Approach 1:
The patent applies composite materials consisting of a polyamide matrix combined with reinforcing elements (fibers or particles) to manufacture cryogenic tank liners. This composite structure provides the necessary mechanical strength while maintaining low density, thereby reducing the overall mass of space launchers compared to traditional metallic alloy solutions.
Solution Approach 2:
The patent changes the material parameters by selecting specific polyamides with appropriate glass transition temperatures and mechanical properties, combined with specific reinforcement types and ratios, to achieve the required strength-to-weight ratio for cryogenic tank applications.
2Reliability
If thermoplastic fluoropolymer (ETFE) is used for the liner, then LOX compatibility is achieved, but permeability to oxygen and helium is high which compromises sealing performance
Solution Approach 1:
The patent uses composite materials where a polyamide matrix is combined with reinforcing elements that simultaneously provide structural integrity and reduce permeability. The composite structure creates a more effective barrier against gas permeation while maintaining LOX compatibility, overcoming the limitations of pure fluoropolymer materials.
Solution Approach 2:
The patent applies local quality enhancement by incorporating specific reinforcement phases within the polyamide matrix that target permeability reduction in critical areas, while the bulk material maintains its LOX compatibility and structural functions.
3Strength
If composite materials with epoxy or polyurethane matrix are used, then structural function is improved, but LOX compatibility according to ASTM D2512 standard is not demonstrated
Solution Approach 1:
The patent changes the material parameters by selecting polyamides with specific thermal and mechanical properties that are inherently compatible with liquid oxygen, replacing epoxy or polyurethane matrices that lack demonstrated LOX compatibility. The selected polyamides undergo specific thermal treatments to optimize their properties for cryogenic applications.
Solution Approach 2:
The patent employs a liner made of polyamide-based composite material that can be manufactured more economically than metallic alternatives and provides sufficient service life for the intended application, replacing expensive metallic components while maintaining safety and performance requirements.
4Strength
If metal alloys are used for cryogenic tanks, then structural integrity is ensured, but manufacturing cost is high due to significant material losses through machining
Solution Approach 1:
The patent employs a liner made of polyamide-based composite material that can be manufactured more economically than metallic alternatives, reducing material losses and manufacturing costs while providing sufficient structural integrity and service life for the application.
Solution Approach 2:
The patent changes the material form from metallic alloys requiring extensive machining to polyamide-based composite materials that can be formed through molding processes, significantly reducing manufacturing complexity and cost while maintaining the required structural properties.
Data Source
AI summary
The invention relates to the use of a composite material for the manufacture of a containment device for a cryogenic liquid and also to a device for the containment of a cryogenic liquid which comprises at least one layer made of this composite material. The composite material is obtained from a composition which comprises, in weight percentages relative to the total weight of the composition: - from 60% to 90% of a polyamide selected from polyamides 6, 6,6 and 6/6,6 and mixtures thereof; - from 10% to 30% of a primary synthetic graphite that is in the form of particles; and - from 0% to 10% of an antioxidant. Applications: manufacture of cryogenic tanks and, in particular, of liquid oxygen tanks, in particular for a space launcher; manufacture of supply lines for cryogenic liquids and, in particular, for liquid oxygen; manufacture of any device allowing the storage, transport and/or supply of a pressurized gas.