A review of the multi-component utilisation of coal fly ash

Structural and mechanical properties of metallic–intermetallic laminate composites produced by explosive welding and annealing

https://estudogeral.sib.uc.pt/bitstream/10316/27386/1/Effect%20of%20explosive%20characteristics%20on%20the%20explosive%20welding.pdf

Effect of explosive characteristics on the explosive welding of stainless steel to carbon steel in cylindrical configuration

Some rocky objects on Earth originated on other planets (e.g. Martian meteorites). Modelling of interplanetary transfer times (Mars-Earth) and calculations of the survival of cells and spores in the radiation environment of space show that this is not an insurmountable obstacle to the successful delivery of life from one planetary surface to another via these rocks. However, the initial launch into space and the subsequent arrival at a new planet involve short-duration extreme accelerations, and shock pressures in the 1-100 GPa range. Recently it has been shown that survival of such accelerations and at such shock pressures is possible. Here we show that in hypervelocity impacts (which involve extreme short-duration accelerations), as shock pressures vary from 1 to 78 GPa, the survival rate (N/N 0 ) for Rhodococcus erythropolis cells falls from 10 -4 to 10 -7 . Whilst survival rates are low at 78 GPa, they are still finite. For a different organism, Bacillis subtilis, the survival rate at 78 GPa was found to be of the order of 10 -5 , ι.e. significantly greater than for the R. erythropolis, indicating that survival rates may vary greatly with different organisms. By contrast, the variation between the survival rate in impacts on agar at 78 GPa for B. subtilis spores versus active B. subtilis was found only to be a factor of 2, well within the experimental uncertainties and not significant. Overall, whilst extreme shock pressures clearly have a deleterious effect on survival rates, it is shown that, even at extreme shock pressures of near to 100 GPa, there is still a finite and sufficient survival rate for this not to be an insurmountable obstacle to successful natural transfer of life through space.

Survival of bacteria and spores under extreme shock pressures

Chemical composition and structure of the shell of fly ash non-perforated cenospheres produced from the combustion of the Kuznetsk coal (Russia)

The detonation velocity of an emulsion explosive containing hollow alumosilicate microspheres (cenospheres) as the sensitizer is measured. The size of the microspheres is 50–250 µm. The relations between the detonation velocity and the charge density and diameter are compared for emulsion explosives containing cenospheres or glass microballoons as the sensitizer. It is shown that for a 55 mm diameter charge, the maximum detonation velocity of the composition with cenospheres of size 70–100 µm is 5.5–5.6 km/sec, as well as for 3M glass microballoons. The critical diameter for the emulsion explosive with cenosphere is 1.5–2 times larger than that for the emulsion explosive with glass microballoons and is 35–40 mm.

Detonation Velocity of Emulsion Explosives Containing Cenospheres

For a fine emulsion explosive, the dependence of the detonation velocity D on the cylindrical-charge diameter d and plane-layer thickness Δ is determined. It is shown that the emulsion explosive considered has low values of the critical diameter (d
 cr ≈ 5 mm) and thickness (Δcr ≈ 2 mm). According to curved front theory, the relation D(d) ≈ (2Δ) is valid and the ratio d
 cr/Δcr is 2.4–2.5.

Critical diameter and critical thickness of an emulsion explosive

Emulsion explosives (EEs) with detonation velocity up to 2–3 km/sec are considered. The compositions contain a large amount of hollow glass microspheres. Examples are given of the use of low detonation velocity EEs to clad metal plates with foils up to 0.1 mm thick and to weld a small-diameter tube to a steel collar in a parallel explosive welding arrangement.

Investigation of low detonation velocity emulsion explosives

Measurements using Velocity Interferometer System for Any Reflector (VISAR) were performed for three high explosives at densities slightly above the natural loose-packed densities. The velocity histories at the explosive/window interface demonstrate that the grain size of the explosives plays an important role. Fine-grained materials produced rather smooth records with reduced von Neumann spike amplitudes. For commercial coarse-grained specimens, the chemical spike (if detectable) was more pronounced. This difference can be explained as a manifestation of partial burn up. In fine-grained explosives, which are more sensitive, the reaction can proceed partly within the compression front, which leads to a lower initial shock amplitude. The reaction zone was shorter in fine-grained materials because of higher density of hot spots. The noise level was generally higher for the coarse-grained explosives, which is a natural stochastic effect of the highly non-uniform flow of the heterogeneous medium. These results correlate with our previous data of electrical conductivity diagnostics. Instead of the classical Zel'dovich–von Neumann–Doring profiles, violent oscillations around the Chapman–Jouguet level were observed in about half of the shots using coarse-grained materials. We suggest that these unusual records may point to a different detonation wave propagation mechanism.

A. V. Plastinin

Papers

Detonation Velocity of Emulsion Explosives Containing Cenospheres

Critical diameter and critical thickness of an emulsion explosive

Investigation of low detonation velocity emulsion explosives

Nonideal detonation regimes in low density explosives

An investigation of ceramic/aluminium composites as shields for hypervelocity impacts