Volume 15, Nº 1 (2022)

On the basis of quasi-equilibrium thermodynamics and molecular dynamics modeling of the process of nanoparticle formation during rapid cooling of carbon gas heated to a high temperature at constant density, the possible pathway for the synthesis of nanocarbon particles is identified through condensation from the gas phase. Thermodynamic calculations take into account the increased enthalpy of formation for carbon nanoparticles. Based on the results of molecular dynamics calculations, three parameterizations of reaction-force fields (ReaxFF-CHO, ReaxFF-c2013, and ReaxFF-PAH) are recommended for molecular dynamics modeling of nanocarbon particle formation.

Soot formation during pyrolysis of ethylene with the addition of alcohols (methanol and butanol) behind shock waves in the temperature range 2009–2524 K and pressure 2.56–3.58 bar has been investigated experimentally. Temperature dependences of optical density were measured by laser extinction at a wavelength of 633 nm and the size of carbon nanoparticles was measured by laser-induced incandescence. Temperature dependences of the induction times for the condensed phase appearance were also obtained. It has been shown that addition of methanol and butanol accelerates and increases the soot yield. The observed promoting effect on soot formation is stronger with the addition of butanol than methanol. The kinetic reasons for the influence of methanol and butanol on ethylene pyrolysis are discussed.

Fire protection of building structures and their elements made of polymer composite materials is carried out using fire clutch equipped with liners made of expandable materials. In the event of fire, the overlap of flame spread along the polymer communications is ensured due to the formation of the fire-insulating foam barrier which does not allow the polymer fusible material to heat up to 120 °C. To clarify reasons for their fire-thermal protective efficiency, comparative studies of the thermal and physical-mechanical properties of two foamed compositions and products of their thermal treatment were carried out. Compositions with the same gas-coke-forming system (ammonium polyphosphate / pentaerythritol / dolomite / thermally expanding graphite) differed in the nature of the binder and thermal protection efficiency. In the course of the study, the following techniques were involved: complex thermal, X-ray phase analyzes, scanning electron microscopy as well as a number of standard and original techniques. It is found that the best physicomechanical, thermal insulating, morphological properties of the thermolysis products of the investigated thermofoamable compositions are achieved by overlapping the temperature ranges of the formation of organomineral framework and volatile thermolysis products. The information obtained on the effect of combining the temperature ranges of the formation of gaseous products by polymer binders and the organomineral framework by the studied gas-coke-forming systems on the qualitative and quantitative characteristics of thermofoamable compositions allows a targeted approach to increasing the efficiency of known foamed compositions and the choice of ingredients for creating new thermal protective materials with improved properties.

The article describes the results of testing the developed device for optical registration of detonation processes. Some ways which help improving the quality of the obtained images registered during the experiments as well as methods of reducing both computational resources and time of data processing are investigated and described. Software and hardware methods of image adjustments and area recognition are considered. The article describes methods which are suitable for a specially designed device for recording detonation waves. The developed device was tested and showed its ability to register detonation processes provided acetylene or other carbon-containing gas for highlighting. Important feature of the device is the ability to conduct video recording by one 1092-pixel line using the maximum frame rate.

The paper presents new experimental results on the dynamics of the cloud of explosive combustion products of the mechanoactivated composition Al/CuO. The parameters of the cloud of combustion products depending on the mass of the mixture were determined using the methods of high-speed photoregistration, pyrometric measurements, and photovoltaic and electrocontact sensors. Various methods of ignition and formation of the product flow are considered. Optimal conditions for the formation of a torch for ignition of combustible gas–air mixtures have been determined.

An improved model of the detonator optical capsule was created on the basis of a standard detonator capsule No. 8 with an improved optical-fiber radiation input system initiated by a continuous infrared laser with a wavelength λ = 975 nm. Photosensitive compositions based on primary explosives — lead azide, diazodinitrophenol, fast burning complex compound — bis(ethylenediamine)-copper-(II)-perchlorate, and a secondary explosive CL-20 with an addition of 0.5% photoabsorbing nanodisized powders of aluminum, copper oxide, and graphite were studied. In the course of the work, the run-up distance and time of combustion-to-detonation transition were determined at a laser radiation power of 3.3 W.

The quality of pyrotechnic products is controlled on the basis of calorimetric measurements of their heats of combustion in a calorimetric bomb. The accuracy of calorimetric data on the heats of combustion of substances is determined, to a large extent, by the relative measurement method — the matching of the conditions of the calibration experiment with reference benzoic acid and the test measurement. Documents regulate the measurement of the heats of combustion of compositions in bomb calorimeters, determine the layout of the reference benzoic acid and test samples, as well as the mode and test scheme. The disadvantage of the document is the violation of the conditions of the test method relativity — the need for the onset of a regular thermal regime in the experiment is not taken into account. It is shown that the duration of measurements of pyrotechnic samples exceeds the time of calibration experiments due to the duration of cooling of a large amount of solid end products of the reaction, which ultimately affects the correctness of the results obtained. In the work on simulators, the influence of the duration of the main period of the experiment on the process of heat transfer was experimentally demonstarated. The value of the error of the measurement result from the process of heat transfer in the bomb, associated with the duration of the main period of the experiment, was determined. A method for conducting an experiment with enhanced heat transfer of combustion products and a minimum duration is suggested. Technical improvement of calorimetric tests is recommended. The quality of pyrotechnic products is controlled on the basis of calorimetric measurements of their heats of combustion in a calorimetric bomb.