•Twelve semiconductor bridge igniters were selected to study the ignition characteristics.•The critical ignition voltage is positively proportional with the bridge area.•The variation law of ignition time with charge type was presented.•The relationship between critical ignition voltage and charge type was concluded.•The ignition time of SCB/N-LS/LA igniter is very close to that of SCB/LA igniter when high discharge voltage is used.Eight different sizes of semiconductor bridges and three kinds of charges, namely normal-lead styphnate (N-LS), lead azide (LA) and the double stacked charge (N-LS/LA), were selected to study the ignition characteristics of semiconductor bridge igniters under capacitor discharge conditions. The Neyer D-optimal Method was utilized in the experiments to explore the critical ignition voltages of the igniters. The relationships among the ignition voltage, current, resistance, and ignition time as well as other parameters of these igniters were analyzed. The results obtained were as follows: 1) The critical ignition voltage is positively proportional with the bridge area for the igniters possessing identical charge and ignition mechanism. 2) The ignition time and critical ignition voltage are related to the charges. The relationship of ignition time and charge following the short to long ranking is LA, N-LS/LA, and N-LS, but the relationship of critical ignition voltage and charge follows the opposite ranking. 3) The electroexploding ignition mechanism brings about shorter ignition time than electrothermal ignition mechanism for the igniters with identical charge, but the electroexploding ignition mechanism is accompanied by higher critical ignition voltage than the other.

Mixture of carbon black, copper and lead was used as catalyst of high-content RDX-composite-modified double base propellant. To enhance the catalytic effect and improve the flaring performance, metal oxide deposited on carbon nanotubes (CNTs) are replaced with afore-mentioned catalyst. A new type of nano-combustion catalyst is synthesized with microemulsion process. In present work, ternary diagram was adopted to analyze the essential factors which affect microemulsion, including temperature, surfactant or cosurfactant and concentration of solution in order to find the best technical parameters and thus to control the core formation and growth of oxides on the nano-template. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) are applied to characterize the products. Through observation of microstructures and analysis of crystal structure, it is confirmed that nano-oxides are deposited on the surface of carbon nanotubes. Its particle size is below 50 nm. According to propellant components, a certain amount of combustion catalyst and RDX will be mixed. PbO·CuO/CNTs can catalyze thermal decomposition of RDX by thermal analysis. The results show that the new catalysts obviously accelerate the decomposition of RDX, and the peak temperature of decomposition reduce by 14.1 °C. The catalytic effect of nano-catalyst is better than original catalyst.

A criterion for the intercalation of a metal chloride in a molten state into graphite was proposed based on the thermodynamics of the intercalation reaction and chemical band theory. The valence electronegativity of element and ionic potential are taken as the chemical band parameters and a band parameter function γ is defined as a criterion to select a guest metal chloride to prepare a graphite intercalation compound (GIC). The ability of a metal chloride to be intercalated into graphite and the stability of the resulting GIC are estimated. The results show that GICs synthesized at a temperature lower than 700 °C are more stable when a metal chloride is chosen from the region of γ≤1.2. A metal chloride with γ between 1.2 and 1.8 cannot be easily intercalated into graphite alone. The metal chlorides with γ≥1.8, most of which are alkaline earth chlorides or alkali metal chlorides, are not appropriate as guests to prepare GICs by a molten salt method. The criterion is consistent with the experimental data and some new expected results are also obtained.