| Hydrogen storage alloys are expected to improve specific impulse when they are usedin propellants because of their high combustion heat and low molecular weight gaseousproduct H2O generated from combustion of the released H2. In this paper, hydrogen storagealloys were used as metal combustion agent and applied to HTPB, GAP and PET compositesolid propellants, whose combustion performances were studied by TG/DSC,decomposition kinetics, PDSC, burning rate, explosive heat, ignition delay time andcombustion wave structure methods. The main work of this paper and the results obtainedare as follows:(1) Hydrogen storage alloys of A20and A30were prepared by ball milling methodwhich makes Al cover onto MgNiB based hydrogen storage alloys. A20and A30havespherical structure, their density are2.463g/cm3and2.437g/cm3, their theoreticalcombustion heat are32343kJ/kg and33425kJ/kg, their combustion efficiency are93.87%and94.32%, their theoretical hydrogen storage capacity are0.684%and1.064%,respectively. XRD and MS results indicated that, H in A20and A30are existed as physicaladsorption and hydride (MgH2) forms, whose hydrogen desorption temperature are150~300℃and350~420℃, respectively. Hydrogen release kinetics results showed thatactivation energy of MgH2decomposition in A20and A30are338.18kJ/mol and338.24kJ/mol, respectively.(2) Thermal decomposition performances of A20and A30were studied by TG/DSCmethods. The results showed A20and A30have both adsorption effects and catalysiseffects on thermal decomposition of AP. Adsorption effects, which are related to the hugespecific surface area of A20and A30, increase AP decomposition temperature, make thedecomposition of AP more completely and improve the heat release of system. Catalysiseffects, which are related to MgO, NiO, B and alloys defects in A20and A30, decrease APdecomposition temperature and activation energy, and prompt more AP decompositionstages appear.(3) Hydrogen storage alloy/AP/HTPB propellants, whose combustion performanceswere studied by ignition delay time, explosive heat, burning rate and combustion wavestructure methods, were prepared. The results showed that, compared to Al/AP/HTPBpropellant PA0, Hydrogen storage alloy/AP/HTPB propellants PA20and PA30have low ignition delay time, high explosive heat, high burning rate, high burning surfacetemperature and good gas phase combustion performance. Ignition delay time (65.2W·cm-2)of PA30is327.0ms. Explosive heat, burning rate (7MPa), pressure exponent of PA20andPA30are7300.60J·g-1and7489.20J·g-1,9.53mm/s and10.66mm/s,0.35and0.44,respectively. Burning surface temperature of PA30is761.33℃.(4) Al/AP/GAP propellant formulations were optimized form plasticizer type, solidparticle size distribution, GAP prepolymer, plasticized ratio and R value, based on whichhydrogen storage alloy/AP/GAP propellant formulations were obtained. Hydrogen storagealloy/AP/GAP propellants have good mechanical property, the maximum tensile strengthand strain of which are0.82MP and32.63%, respectively. Combustion performances ofhydrogen storage alloy/AP/GAP propellants GA20and GA30were studied. The resultsshowed that, ignition delay time (106.5W·cm-2) of GA20and GA30are161.2ms and53.4ms, which are higher than GA0by161.2ms and153.4ms; Explosive heat of GA20andGA30are6498J·g-1and6604J·g-1, which are higher than GA0by5.92%and7.64%;Burning rate (7MPa) of GA20and GA30are13.01mm/s and14.91mm/s, which are higherthan GA0by55.25%and77.92%; Pressure exponent of GA20and GA30are0.15and0.19;Burning surface temperature of GA30is761.33℃, which is lower than GA0by69.68℃;Both of them have good phase combustion performances.(5) Hydrogen storage alloy/AP/PET propellant formulations were optimized to reachgood mechanical properties, the maximum tensile strength and strain are1.58MP and37.33%, respectively. Combustion performances of hydrogen storage alloy/AP/PETpropellants were studied. The results showed that, NA20and NA30have low ignition delaytime, high explosive heat, high burning rate, high burning surface temperature and good gasphase combustion performances than NA0. Ignition delay time (72.9W·cm-2), explosiveheat, burning rate (7MPa), pressure exponent, burning surface temperature of GA20andGA30are277.8ms and261.2ms,6896J·g-1and7193J·g-1,7.60mm/s and10.87mm/s,0.19and0.35, respectively.(6) Combustion model of hydrogen storage alloy/AP/HTPB, hydrogen storagealloy/AP/GAP and hydrogen storage alloy/AP/PET propellants based onthermal decomposition performances and combustion performances were established, andsteady state reaction mechanism of each reaction zone of the propellants were summarizedfrom mass and heat transfer points.(7) Sensitivity of hydrogen storage alloy/AP/HTPB, hydrogen storage alloy/AP/GAP and hydrogen storage alloy/AP/PET propellants were investigated, the results showedthat, three kinds of propellants have low sensitivities to meet the safety requirements ofpropellants. |
PDF Full Text Request