This study investigates the electro-spark initiation of a chemical reaction in a porous mechanochemically activated mixture of aluminum powder and copper oxide. The conditions for the formation and parameters of the electrical discharge are described. Based on the measurement results and a number of assumptions, an estimate is given for the volume of plasma penetration into the pores of the mixture. Experiments are conducted to initiate combustion in semi-enclosed volumes with a mass of up to 1 g to provide indirect evidence of the completeness of the chemical reaction. Combustion occurs with the formation of a flame in open space, and its dynamics over time are presented as a result of the parameters of the electrical discharge. The experimental results are approximated by appropriate functions, representing the dependences of the ignition delay time on the energy density of the electrical discharge and the flame formation rate of the mixture on the discharge energy. From the obtained dependences, the critical values of the energy parameters of the electro-spark discharge for stable ignition of the thermite mixture are determined.

Проведено исследование электроискрового инициирования химической реакции в пористой механоактивированной смеси порошков алюминия и оксида меди. Описаны условия формирования и па- раметры электрического разряда. Определено влияние геометрии узла инициирования на энергетические параметры искрового разряда. На основе результатов измерений и ряда предположений дана оценка объема проникновения плазмы разряда в поры смеси. Проведены эксперименты инициирования горения зарядов в полузамкнутых объемах при массе до 1 г для получения косвенных свидетельств о полноте химического взаимодействия. Экспериментальные результаты аппроксимированы функциями в виде зависимостей задержки инициирования реакции от плотности энергии электрического разряда и ско- рости формирования факела горения смеси от энергии разряда. По найденным зависимостям определены пограничные значения энергетических параметров электроискрового разряда для реализации стабильного зажигания термитной смеси

The electric-spark initiation of thermite mixtures based on nanosized powders of aluminum and copper oxide has been studied. Data on the effect of the electric spark discharge energy on the ignition delay were obtained. During the initiation of long cylindrical samples of mixtures with a low-current spark, two types of unsteady combustion were observed. The first type is characterized by the exponential establishment of constant burning rate. The second type is characterized by regions with incomplete reaction in the main propagation direction. To obtain steady combustion of a thermite mixture with a minimum ignition delay time, it is necessary to use a discharge energy of more than 5 mJ per 1 mm 2 of the mixture surface.

Приведены новые экспериментальные результаты по динамике облака продуктов взрывного горения механоактивированного состава Al/CuO. С помощью методов скоростной фоторегистрации, пирометрических измерений, фотоэлектрических и электроконтактных датчиков определены параметры облака продуктов горения в зависимости от массы смеси. Рассмотрены различные способы зажигания и формирования потока продуктов. Определены оптимальные условия формирования факела для зажигания горючих газовоздушных смесей.

The results of measurements of the mechanical characteristics of cured epoxy composites containing small and ultrasmall additions of single-walled carbon nanotubes in the concentration range from 0 to 0.133 wt % under static and dynamic loads are presented. Static measurements of strength characteristics have been carried out under standard test conditions. Measurements of the Hugoniot elastic limit and spall strength were performed under a shock wave loading of the samples at a deformation rate of (0.8–1.5) ß 105 s-1 before the fracture using explosive devices by recording and subsequent analyzing the evolution of the full wave profiles. It has been shown that agglomerates of nanotubes present in the structure of the composites after curing cause a significant scatter of the measured strength parameters, both in the static and in the dynamic test modes. However, the effects of carbon nanotube additions in the studied concentration interval on the physical and mechanical characteristics of the parameters were not revealed for both types of loading.