Erosion effects of atomic oxygen on carbon nanotube arrays in different incidence direction

Abstract

The erosion effects of atomic oxygen (AO) in different incidence direction on carbon nanotube (CNT) arrays have been studied by ground-based AO simulation facility. The surface morphologies and the molecular structures of CNT arrays before and after AO experiments have been characterized by scanning electron microscopy and Raman spectroscopy. It is shown that the morphologies of CNT arrays are quite different from those before AO experiments. It is presented that both bombardment effect and the oxidation effect of AO will contribute to the erosion effects on CNT arrays. Carbon nanotube arrays will be etched away in AO environment, but the AO erosion yield of CNT arrays is different with different AO incidence direction. It is proposed that the density of CNT-based material may also affect the erosion yield. KEYWORDS atomic oxygen, bombardment effect, carbon nanotube arrays, erosion effects, oxidation effect 1 | INTRODUCTION Because of their unique properties of extremely high strength, high stiffness, low density, good chemical stability, and high thermal and electrical conductivities, carbon nanotubes (CNTs) will have great potential applications in many fields. Particularly in space applications, the potential implementations of these advanced materials have been predicted to have a large impact on future spacecraft. 1 Carbon nanotube-based materials can be used for electromagnetic interference shielding and electrostatic discharge protection on spacecraft. 2,3 Extremely sensitive chemical sensors based on CNTs are suitable for detecting trace amounts of residual atmosphere in space. 4,5 Replacement of conventional spacecraft structural materials (composites and metal) with advanced composites derived from lowdensity high-strength CNTs can greatly reduce spacecraft weight. 6-9Extremely black materials made by CNTs can greatly suppress stray and scattered light in space-borne optical instruments, which is important for achieving the design performance of the instrument. 10-14 But in all these applications above, the CNT-based materials have to be exposed in space environments and suffer extreme space environments.Atomic oxygen (AO) is one of the predominant species in low earth orbit (LEO), which is formed by photodissociation of the residual diatomic oxygen that is exposed to the sun's ultraviolet radiation. [15][16][17] As a highly reactive form of oxygen, AO has sufficient kinetic energy of about 5 eV to break chemical bonds. As a result, AO can interact readily with many materials on spacecraft, which are exposed to the space directly. Specially, all hydrocarbon-based polymers and graphite would be easily oxidized and eroded, which lead to degradation in performance of these materials. [18][19][20] So AO is a great threat to the durability and reliability of spacecraft components. In development of new materials intended for operation in aerospace in LEO, such as CNT-based materials, one of the most important problems is the assurance of their resistance against the impact of the AO.A few studies had been co...

Synthesis and property evaluations of highly filled polyimide composites under thermal cycling conditions from −190 °C to +200 °C

“…Polymer composite materials, developed for the space industry, must withstand the loads of space flight, including high structural properties and resistance to high vacuum, radiation, micrometeorite particles, in particular, atomic oxygen, etc. [11][12][13][14][15]. In addition, the developed composites should have a wide operating temperature range from −190°C to +200°C [16].…”