The Effect of Silicon Powder Characteristics on the Combustion of Silicon/Teflon/Viton Nanoenergetics

Abstract

Due to its thin passivation layer, potentially good aging characteristics, and ease of surface functionalization nanoscale silicon (Si) may offer some advantages over nanoaluminum as a reactive fuel in nanoenergetic compositions, particularly with fluorine‐based oxidizers. Currently, Si nanopowder can be quite expensive and the quality of commercial powders has been found to vary drastically. As a result limited efforts have focused on the role of specific surface area, active content, morphology, and dominant particle size of the powder have on the combustion performance. In this work we report the effect of such characteristics on the combustion of silicon (Si)/polytetrafluoroethylene (Teflon)/FC‐2175 (Viton) (SiTV) nanoenergetics. A cost effective combustion synthesis route, salt assisted combustion synthesis, was used to produce several Si powders and these were directly compared to commercial nanoscale Si powders. Reactive mixtures of SiTV were burned at atmospheric conditions and burning rates, combustion temperatures, spectral intensities, and effective plume emissivities were measured. Measured combustion temperatures ranged from 1664 to 2380 K and were limited by Si powder active content. This was found to drive plume emissivity and maximum spectral intensity, which had values ranging from 0.10 to 0.55 for effective plume emissivity and 17.6 to 48.1 kW m−2 sr−1 μm−1 for maximum spectral intensity. Burning rates ranged from 0.7 to 3.4 mm s−1 and were found to be dependent on the dominant particle size of the powder. Powders synthesized with salt assisted combustion resulted in comparable burning rate, plume emissivity and maximum spectral intensity to porous Si powder (Vesta Ceramics).

Electroless Deposition and Ignition Properties of Si/Fe2O3 Core/Shell Nanothermites

“…Si also has a thinner native oxide layer of 1–3 nm than Al, and it is resistant to electrostatic discharge. Importantly, the surface of Si can be easily functionalized, , facilitating the use of coating and surface modification to tailor its ignition and burning properties. Several previous studies have shown that Si-based thermites have comparable combustion properties as Al-based thermites, ,, in terms of adiabatic combustion temperatures (∼3000 K) and burning rates (40–530 m/s) .…”

An extremely superhydrophobic and intrinsically stable Si/fluorocarbon energetic composite based on upright nano/submicron-sized Si wire arrays

“…Si + C 2 F 4 (c) / SiF 4 + 2C DH Ө ¼ À6.21 kJ g À1 (1) systematically investigated the roles of specic surface area, active content, morphology, and particle size of the Si powder on the combustion behaviour of Si/PTFE/Viton nanoenergetic composites. 17 However, powder-mixing technique was used in these studies to prepare nanoenergetic composites, and hence the interfacial contact and distribution of fuel and oxidizer are rather random. As one kind of nanostructured energetic composites, nano-porous Si-based nanoenergetics attract much more attention.…”

Facile Thermal and Optical Ignition of Silicon Nanoparticles and Micron Particles

“…Some studies have investigated the combustion properties of Si particles with solid oxidizers (e.g., sodium perchlorate and fluorinated compounds), including flame propagation speeds and pressurization rates, 9−11 and found that more intense burning and faster flame propagation are achieved when the size of Si particles decreases from microns to nanometers. 11 One study looked into the ignition properties of micron-sized Si particles in air by electric spark ignition 12 and found that the minimum ignition energy decreased from 2.9 J for 18 μm Si particles to around 0.06 J for 3.6 μm Si particles. Other studies have investigated the ignition properties of porous Si (P−Si), which is crystalline Si containing nanosized pores with hydrogen terminated surfaces.…”

“…Such requirements call for understanding and quantification of the ignition and combustion properties of Si particles. Some studies have investigated the combustion properties of Si particles with solid oxidizers (e.g., sodium perchlorate and fluorinated compounds), including flame propagation speeds and pressurization rates, − and found that more intense burning and faster flame propagation are achieved when the size of Si particles decreases from microns to nanometers . One study looked into the ignition properties of micron-sized Si particles in air by electric spark ignition and found that the minimum ignition energy decreased from 2.9 J for 18 μm Si particles to around 0.06 J for 3.6 μm Si particles.…”