Burn Rate of Calcium Sulfate Dihydrate–Aluminum Thermites

Abstract

The energetics of cast calcium sulfate dihydrate-aluminum thermites were investigated. The casts were prepared from water slurries with a solids content below 65 wt %. The base case thermite comprised 60 wt % calcium sulfate dihydrate as the oxidizer with 40 wt % aluminum as fuel. The heat of hydration of the base case was 83 ± 4 kJ·kg (dihydrate basis) and the initial setting time was about 100 min. The compressive strength reached 2.9 ± 0.2 MPa after 3 days of drying in ambient air. The open air burn rate was 12.0 ± 1.6 mm· s and a maximum surface temperature of 1370 ± 64 °C was recorded with a pyrometer. Bomb calorimetry indicated an energy output of 8.0 ± 1.1 MJ·kg, slightly lower than predicted by the Ekvi thermodynamic simulation. Substitution of 10 wt % of the oxidant with copper sulfate pentahydrate significantly decreased the initial setting time of the casts to less than 30 min but a secondary aluminum oxidation reaction commenced after 2 h. The density of the castings was varied by either adding hollow sodium borosilicate microspheres or by adding excess water during the casting process. The addition of the hollow glass microspheres caused a decrease in the burning rate. Dehydration of the casts by thermal treatments at either 155 or 200 °C led to significant increases in the burning rate.

Simultaneously Altering the Energy Release and Promoting the Adhesive Force of an Electrophoretic Energetic Film with a Fluoropolymer

“…Thermites, a kind of composite energetic material (EM) consisting of solid metal fuel and oxidizer particles, have been applied in high-energy exchange components, such as electronic packaging, self-propagating welding, and self-propagating high-temperature diffusion welding. , Reactive films as the typical form of thermites, also termed thermite laminates, have attracted a great deal of interest with respect to their compatibility and high energy and power density (superior to those of supercapacitors) . Various applications of reactive coatings have been realized in microelectromechanical systems, microignitor devices, microelectronics, and bonding of materials …”

Effect of Cu2+ on the nucleation kinetics and crystallization of rod-shaped CaSO4·2H2O in aqueous solution

“…Calcium sulfate is a common inorganic compound which is of huge environmental and industrial importance. In nature, it is present as large-scale deposits of CaSO 4 $2H 2 O (DH), CaSO 4 -$0.5H 2 O (HH) and CaSO 4 (AH), [1][2][3][4] and is the source material for the preparation of high volumes of compounds including plaster and cement and for use in agricultural applications. [5][6][7] In particular, DH, as a crucial mineral, is widely used in industry for bone tissue regeneration, as a medical carrier and in 3Dprinting.…”