Mechanism Of Delay Composition Combustion And Influence Of Pressure On Combustion

Mechanism of delay composition combustion and influence of pressure on combustion was discussed in this paper. A drilled organic glass block was filled with delay composition (Pb3O4:Si=85:15). Placed the glass block in a pressure-resistant steel container in which the pressure can be adjusted. High-speed camera recorded the moving process of combustion wave front. Observed propagation velocity was not constant but rhythmic "flashing" leaps. The bright sped faster, and the dark slower. Combustion rate between short intervals of photos was obtained by calculation. Comparison showed that the combustion rate was pulsatile, and pulsation cycle was basically1.0mm wide with time of14ms. Analysis suggested that the cause of pulse was gas expansion of thermal decomposition in heating area when the burning delay composition was shifted. Crack of displacement hindered the heating in heating area and slowed the burning rate. So pulse combustion generated. The reason for unsteady pulsation cycle was uneven composition density or mixing.DSC-TG MS recorded the reaction mechanism of Pb3O4-Si delay composition thermal decomposition and combustion. The reaction process was mainly divided into two steps. The first step was solid-solid phase pre-reaction when red lead and silicon diffused in the form of atomic lattice; The second step was main gas-solid phase reaction when oxygen generated from the decomposition of red lead reacted with silicon. The apparent activation energy, pre-exponential factor and rate constant of the Pb3O4-Si reaction was calculated by Ozawa and Kissinger method.By using homemade delay composition combustion gas production device measured that1g red lead-silicon (Pb3O4:Si=85:15) burned with5.72×10-4mol gases generated.Delay composition burned under pressure from0.1to1.0MPa. Contrast found that combustion rate had a linear acceleration as (the pressure increased. Research showed that the greater the proportion of oxidant red lead, the less gas decomposition. Gas phase reaction should be more dominant. Lead delay element of3period burned under pressure from0.1to1.0MPa to test burning rate. The experiments showed that the burning rate increased with the atmospheric pressure.Observed both ends of lead delay element after burning by microscope showed that both ends presented "horn" shape. It proved that lead element was deformed at both ends under high pressure. Caused that the medicament couldn’t burn completely in the lead element and influenced the delay precision. Observation on the residue showed that silicon particles gathered and it has not fully participated in chemical reactions.