Silicon Carbide Nanotubes: From Finite Single-Walled to Infinite Multi-Walled

Abstract

A review of research of silicon carbide nanotubes from single-walled to multiwalled structure is presented. Electronic properties of silicon carbide nanotubes have very interesting characters due to the partial ionic nature of Si C bond. Many theoretical studies have shown that the silicon carbide nanotubes can be promising medium for hydrogen storage. The possibility of capping a silicon carbide nanotube by fullerene hemisphere cap provide further applications in field emission displays, chemical couriers and as liquid crystals. Also, the capping provides an insight into the possible synthesis pathways to single-walled and multi-walled silicon carbide nanotubes. Electronic and structural properties of double-walled silicon carbide in reviewed in detail. The possibility of metallic multiwalled silicon carbide nanotubes is also explored. The studies so far have not indicated any metallic behavior in multiwalled silicon carbide nanotubes.

Effects of oxygen absorption on the electronic and optical properties of armchair and zigzag Silicon Carbide Nanotubes (SiCNTs)

“…This Si and C atoms together forms SP2 hybridization to form hexagonal SiC sheet [11]. In order to overcome limitations of bulk SiC and 2D SiC sheet for applications in science and technology, nanotubes form of SiC were hybridized and investigated [12]. SiC nanotubes (SiCNTs) are nanotubes formed by rolling 2D sheet of SiC to form a seamless cylinder [13], they are less than 100 nm in diameter [14], and they can be single walled SiCNT (SWSiCNTs) or multi-walled SiCNT (MWSiCNTs) depending on the number of stacking tubes.…”

Velcro-Inspired SiC Fuzzy Fibers for Aerospace Applications

“…Better functioning, easier to produce, lightweight, mechanically/thermally/electrically robust, chemically inert materials with a highly active surface area are constantly sought after to improve materials currently used in the extreme environments encountered in many applications, specifically aerospace applications. , The National Aeronautics and Space Administration (NASA), the leader in aerospace technology, is interested in the investigation of ultralight-weight materials that function in a wide variety of capacities, such as thermal and mechanical. Silicon carbide has been long known and used for its high hardness, low density, high-temperature mechanical strength, corrosion, radiation, oxidation resistance, chemical inertness, wide band gap (2.2–3.3 eV), and high decomposition temperature (2545 °C). − In the form of fiber, silicon carbide can utilize these advantageous mechanical and thermal properties with a diameter (8.5–15 μm) small enough to have increased flexibility but large enough to be able to add continuous strength to a composite material. − The synthesis, composition, crystallinity, and mechanical and thermal properties of SiC fibers have been optimized since the 1970s, primarily for structural reinforcements in ceramic matrix composites (CMCs) for use in air at temperatures above 1000 °C. ,, Specifically, the most current, cutting edge technology in aerospace applications is the use of woven, layered near-stoichiometric SiC fibers (SiCF) in SiC CMCs for high heat engine parts to enable the creation of turbo engines that are larger and operate at higher temperatures than any other engine previously constructed. − To achieve its ultimate application temperature and life cycle, however, the SiCF–SiC matrix composite must overcome several problems, resulting from mechanical stress-induced cracks and/or oxidation. The three most significant problems include: fiber pullout from the matrix or fibers being pulled from the matrix resulting in a void where the fiber was previously; weakness in the z -direction, normal to the fiber weave, causing the fibers to slide in the x and y directions, parallel to the fiber weave, as seen relative to the schematics in Figure (a); and/or oxygen to enter the composite and break down the fiber…”