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Sujet de stage / Master 2 Internship

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Development and study of composite materials based on carbon nanotubes for application to cryogenic fluid reservoirs

Contact: CHARON Emeline, , emeline.charon@cea.fr, +33 1 69 08 63 16
Summary:
The subject of this internship is part of a thesis project aimed at finding the best way of integrating carbon nanotubes into laminated composite materials, capable of bridging microcracks in the matrix of these composites, in order to limit fuel leaks from launch vehicle cryogenic tanks.
Possibility of continuation in PhD: Non
Deadline for application:04/04/2024

Full description:
The emergence of new "low-cost" launcher technologies is driving research and development into new material architectures that are both lightweight and resistant to thermomechanical and chemical stresses. In particular, the development of new composite structures can play a very important role in terms of weight savings. Among the various approaches already investigated, the lightening of the cryogenic tank can significantly improve the performance of a propulsion stage.

In this field, studies are reporting the development of composite materials with a variety of organic matrices (thermosetting or thermoplastic) incorporating reinforcements of different kinds: glass fibers, Kevlar or carbon fibers, carbon blacks, graphene, silica nanoparticles, and even more recently carbon nanotubes (CNT). The latter, with their exceptional physical and mechanical properties, as well as their light weight, could bring significant advantages to composite materials that could potentially be used to make cryogenic tanks. However, the state of the art reveals a lack of study of these nanomaterials in cryogenic environments. Indeed, to our knowledge, composite materials incorporating CNTs have been studied in liquid nitrogen environments, enabling us to qualify their low-temperature behavior in terms of damage, but there are no studies dealing with the compatibility of these materials in environments of interest such as liquid oxygen.

In this context, a preliminary study carried out by CEA and CNES has led to the development of the first innovative composite building blocks incorporating CNTs. This led to the selection of a cyanate ester matrix (known as CE) and initial tests under a pure oxygen gas atmosphere (Gox), to determine the material's auto-ignition temperature. The results of these tests demonstrated the beneficial effect of CNT [1].

The subject of this internship is part of a thesis project aimed at finding the best way of integrating carbon nanotubes into laminated composite materials, capable of bridging microcracks in the matrix of these composites, in order to limit fuel leaks from launcher cryogenic tanks. Knowing the mechanical and thermal stresses involved, the aim is to demonstrate the effectiveness of CNTs in terms of material damage tolerance. Damage tolerance is directly linked to strength and sealing performance.

To achieve this, three ways of integrating carbon nanotubes are proposed:
1-Growth of carbon nanotubes (CNTs) directly on carbon fibers by CCVD [2],
2-Transfer of a mat of aligned carbon nanotubes on carbon fiber fabric pre-impregnated with CE,
and 3-Random dispersion of carbon nanotubes in the matrix.

The approach will involve adjusting the synthesis parameters (time, injection, reactive atmosphere...[3]) with the aim of controlling the characteristics of the CNTs formed (alignment, length...). Particular attention will be paid to the control of length, diameter and density, notably by electron microscopy (SEM and TEM), and to the structural quality of the CNTs by Raman spectrometry.
Technics/methods used during the internship:
CCVD, SEM, TEM, Raman spectroscopy

Laboratory
Tutor of the internship

 

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