Study on the Shock Sensitivity of the Hydrolysis Products of Hexachlorodisilane

Abstract

The hydrolysis products of hexachlorodisilane (HCDS) show common heat sensitivity and can become shock sensitive under certain conditions. Study of the shock sensitivity has been difficult due to the unpredictable nature of this phenomenon. We have identified the parameters affecting the shock sensitivity of the materials and developed synthetic methods to consistently prepare the hydrolysis products with a high shock sensitivity. We characterized the composition of the hydrolysis products to be [SiO x (OH)4–2x ] m ­[Si2O y (OH)6–2y ] n ­(H2O) o where x is 0–2, y is 0–3, m is less than n, and o varies. The hydrogen atoms in the silanol groups or absorbed water are the oxidant and the silicon atoms in the Si–Si bonds are the reductant. When the materials are disturbed by a thermal or mechanical impact, fast redox reactions happen to form molecular hydrogen. A sequence of free radical reactions was proposed to explain the shock sensitivity and shock-induced chemical transformation.

Characterization of Shock-Sensitive Deposits from the Hydrolysis of Hexachlorodisilane

“…Some of the particles released sparked. It should be noted that 30 J of impact energy is far larger than the impact energy of a quickly squeezed plier and thus may be classified as nonshock-sensitive by Zhou et al 7 However, such an impact energy is still within the reachable range of a mechanical impact during maintenance work, as highlighted in the 2014 incident and thus merits further study.…”

“…18 It may also explain the variations in shock sensitivity from previous literature. 2,5,7 For example, hydrolysis products prepared by directly adding HCDS to water were not shock-sensitive simply because of excessive water. 7 Whereas a dried deposit from hydrolysis at a low temperature of approximately 10 °C or lower had an increased sensitivity owing to no excess water present.…”

“…More recently, Zhou et al performed a detailed study on the shock and heat sensitivity of the hydrolysis products of HCDS. 7 Synthetic methods were developed to consistently prepare the hydrolysis products with high shock sensitivity. The shock sensitivity was determined by placing a sample between the jaws of a plier that was quickly squeezed to crush it.…”

“…More recently, Zhou et al performed a detailed study on the shock and heat sensitivity of the hydrolysis products of HCDS . Synthetic methods were developed to consistently prepare the hydrolysis products with high shock sensitivity.…”

Identifying the mechanism of formation of chlorinated silane polymer by‐products during chemical vapor infiltration of SiC from CH3SiCl3/H2

“…These by‐products have been well‐studied and identified as chlorinated silane polymers with the formula (SiCl 2 ) n or Si n H x Cl 2 n – x 4,6 . These substances burn slowly in a dry atmosphere, but their hydrolyzed products are extremely dangerous as they can ignite and explode in an inert atmosphere 4,7,8 . Mizushima and Habuka reported that a similar by‐product is formed in the exhaust tube of the SiC‐CVD reactor due to the reaction between C 3 H 8 /SiH 4 /HCl/H 2 .…”