SiO2 aerogel has the characteristics of high porosity and high specific surface area. In order to explore the feasibility of using it as a new infrared functional additive for smoke composition, SiO2 aerogel was mixed with NaNO3 and NH4NO3 saturated solution respectively, and freeze-drying was introduced to make NaNO3 and NH4NO3 deposit in the pores or surface of SiO2 aerogel. So the powder-form infrared functional additive was prepared completely. The new powder not only reduces the frequency of the phenomenon of harden synthesized compound and improves its preparation process, but also guarantees the recovery of prefabricated particle size of SiO2 aerogel in the combustion process. The experimental results show that: when mixed with smoke composition, on the condition that the mixing ratio of additives is 20% and negative oxygen balance is 20, compared with the traditional smoke composition obscuring ratio, the smoke composition synthesized obscuring ratio can be increased by 72% and 47% in infrared band.
Combustion mechanism of magnesium has long been explored. It has been recently shown that spherical magnesium particles with highly active can be used to analyze combustion process in detail with the help of new methods and advanced instruments. This work is aimed at investigating the multiple diffusion reaction of single spherical magnesium particles in accordance with surface composition and combustion remains. Energy Dispersive Spectrometer (EDS), Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) were used to analyze the samples before and after reaction. In addition, combustion of magnesium particle was conducted in a microscope heating system. The results of the study show that an oxygen-rich layer formed on the particle surface before the particle was heated to burn. Dissolved oxygen was detected in this layer and its concentration is lower than that of stoichiometric MgO. The dissolution reaction of oxygen begins before the gas phase combustion and later on, after the gas phase combustion stops, becomes the dominated reaction. It is suggested that there are two sources of MgO formed during the oxidation process, Mg(s) → Mg(g) → MgO(s) and Mg(s) → oxygen-rich layer(s) → MgO(s). The latter is the dominated mechanism of surface heterogeneous reaction.
It is a difficult problem to evaluate the signal parameters of optical radiation characteristics of solid propellant. The research proposes a multispectral evaluation method of propellants radiation signature index (PRSI). The infrared radiation intensity, ultraviolet radiation intensity and visible radiation intensity of both HTPB composite propellant and nitrocellulose propellant were tested with infrared radiometer and ultraviolet and visible light radiation measuring instrument, and then used the method of PRSI to compare the test results. The results show that the PRSI values of UV and visible light produced by the combustion of HTPB composite propellants are significantly larger than those of the nitrocellulose propellants. The multispectral exponential factor evaluation method based on the inherent parameters of propellants, such as mass-combustion heat and burning velocity, can not only compare the difference of spectral characteristics of similar propellants, but also compare different types of propellants.
Illuminant is a porous media consisting of powder materials. The flame of illuminant seems
continuous, but in fact the flame is made up of a substantial number of burning particles, and the
burning particles determine the temperature distribution of the flame. In this paper, the distribution of
the burning particles was first studied using a high speed camera. Then a model of the temperature
field of illuminant flame was established based on the equation of heat conduction and the distribution
function of the burning particles. The temperature field of the illuminant flame was predicted by the
model and the highest temperature was measured using Fourier transform infrared spectrometer. The
model was validated by the experimental results using an infrared thermometer. The results indicate
that a good match has been achieved between the experimental data and the model predicted flame
temperature field of the illuminant based on the distribution of burning particles.
Copper-plated and silver-plated cellulose nitrate flakes, which were prepared by using chemical plating technology, were used to jam infrared detector and millimeter-wave radar. It was tested for the conductivity and infrared jamming performance of plating and also the RCS (Radar Cross Section) performance of millimeter-wave radar. Test results showed that the prepared metal-plated cellulose nitrate flakes have obvious conductivity, and infrared total radiation energy of silver plating and copper plating had approximately increased 32% and 21% respectively. Through determination, the millimeter-wave reflecting property and RCS of silver-plated cellulose nitrate flakes were higher than that of copper-plated cellulose nitrate flakes. Therefore, silver-plated cellulose nitrate flakes can be used as an effective infrared / millimeter wave composite jamming material.
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