Ti-assisted β-SiC nanowhiskers by pyrolysis of PTFE: synthesis and mechanical properties

Abstract

Large quantities of Ti-catalyzed β-SiC nanowhiskers were efficiently prepared via a SHS process by pyrolysis of poly (tetrafluoroethylene) (PTFE). The as-synthesized β-SiC whiskers appear to be structurally uniform with width from 50 nm to 2 µm and length of up to several hundred microns, and they are single crystalline in nature. Results demonstrated that Ti particles could significantly accelerate the absorption and dissolving of Si-and C-related fragments. A Ti-Si-C alloy droplet was detected at the end of an individual β-SiC whisker, which indicated that β-SiC whiskers were grown via the vapor-liquid-solid (VLS) growth mechanism. The elastic bending modulus of individual whiskers was measured by an in-situ transmission electron microscopy (TEM) process; the average value of the elastic bending modulus of individual as-synthesized whiskers was 554 GPa.

Controllable Combustion Synthesis of SiC Nanowhiskers in a Si-C-N System: The Role of the Catalyst

“…Silicon carbide (SiC) has excellent thermal conductivity, chemical inertness, and high value of the Young's modulus, strength, toughness, and optics properties [1][2][3][4]. Thus, SiC was generally used in high temperature, high power, and high frequency as well as in harsh environments.…”

“…The outstanding mechanical properties of SiC nanowhiskers (NWs) make it a promising candidate for the reinforcing phase in ceramic, metal, and polymer matrix composites. SiC NWs also show potential for fruitful applications in field emission displays, nanosensors, nanoscale electro-devices, and optoelectronic devices [1][2][3][4]. To date, many methods [5][6][7][8][9][10][11][12][13][14][15] have been applied to prepare SiC whiskers or NWs, including the most common and commercial methods such as chemical vapor deposition from silanes, thermal decomposition of rice hulls, and thermal reduction of silicon oxides, in particular on silica and carbon solid mixtures [16].…”

“…To get high quality, a complicated post process is needed to get high quality nanowhiskers, since whiskers must be separated from the whiskers/particle and purified of the residual Si and C particles and low melting alloys in the products. These shortcomings cause the high production cost directly or indirectly [1]. Combustion synthesis (CS) is an easy, efficient, and low-cost method to obtain a wide variety of materials [1,2,17].…”

“…These shortcomings cause the high production cost directly or indirectly [1]. Combustion synthesis (CS) is an easy, efficient, and low-cost method to obtain a wide variety of materials [1,2,17]. In comparison with the conventional synthesis methods of SiC whiskers, the CS process possesses significant advantages such as great energy efficiency, high purity of the products, and high production rate.…”

“…Furthermore, not only the effect of the catalyst itself, but also the final status of the catalyst in NWs, in particular in their high temperature applications, should also be taken into account. We have previously reported the fabrication of CSed SiC NWs using titanium powder as a catalyst, but the yield of whiskers needs further optimization [1]. Herein, tungsten (W) was selected as the catalyst because of its high melting point, thus it is not harmful in high temperature structure materials.…”