| The propellant which has higher density special impulse can be applied into ramjet which has no nozzle. Novel high energy solid propellants are generally added mass ultra-fine aluminum powders in order to promote its energy. This kind of propellant contains zirconium powders is 20 percent higher than that contains aluminum powders. However, the electrostatic sensitivity of zirconium powders is very high. It easily spontaneous combusts and explodes in the air. Thus the research emphasis was the improvement of zirconium electrostatic sensitivity.Firstly, the surfaces of Zr powders were coated with poly methyl methacrylate (PMMA) by the method of In-Situ polymerization. Effects of the proportion of monomers and dispersants, temperature, stirring speed and other parameters on the morphology and particle size of composite particles were investigated. Composite particles were characterized by FTIR, SEM TG-DTA and laser particle size analyzer, etc. The results had shown that particles size increases with the increase of monomers proportion amount of monomers, but decreases with the increase of dispersant concentration. At the same time, with the increase of stirring speed, system's dispersibility becomes better and the particles size gets larger.Secondly, the surfaces of Zr powders were coated with co-polymer (P(methyl methacrylate-vinylidene chloride)) by phase separation polymerization. Effects of coating by changing the materials adding method and coating dosage were investigated. The best experimental formulation had been determined. We used instruments such as FTIR, SEM, TG-DTA to test the coating effcts. The results had shown that coating effect of composite particles is better when by means of adding cyclohexane into the polymer solution of Zr powders. The film forming property of Zr/P(MMA-VDC) composite particles was good when coating dosage was 1.0%, and the amount of dissociative co-polymers was few.Finally, the electrostatic sensitivity of Zr powders and Zr/PMMA and Zr/P(MMA-VDC) were tested. The results show that the electrostatic sensitivity of Zr/PMMA and Zr/P(MMA-VDC) is reduced compare to Zr powders. The sample coated with P(MMA-VDC) has much lower electrostatic sensitivity. |
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