Preparation And Application Of Nanometer Strontium Carbonate Quaternary Ammonium Salt Composite Particles

Strontium carbonate(SrCO₃)and quaternary ammonium salt are the commonly used speed reducers for HTPB solid propellants.In order to solve the problem of poor dispersion of SrCO₃ and quaternary ammonium salt(SIOC-TES)(hereinafter referred to as quaternary ammonium salt)in the propellant system,it can play a"synergistic effect"and reduce the burning rate of HTPB solid propellants significantly.In this paper,nano SrCO₃/quaternary ammonium salt composite particles were prepared with micron SrCO₃ and new quaternary ammonium salt as raw materials,and the effects of nano SrCO₃ and quaternary ammonium salt composite particles on the properties of HTPB solid propellant were studied.(1)nano SrCO₃ particles were prepared by mechanical ball milling method.The morphology,particle size,crystal form and particle size distribution of nano SrCO₃ were characterized by transmission electron microscope(TEM),scanning electron microscope(SEM),X-ray diffraction(XRD)and laser particle size analyzer.The results show that when the filling ratio of the ball milling medium is 70%,the rotation speed of the ball mill is1000rpm,and the mass concentration of the material is 8%,the nano SrCO₃ particles are quasi spherical,the particle size d₅₀ is about 70nm,the crystal shape has not changed,and the yield and purity of the products are high.(2)The effect of nano SrCO₃ on the thermal decomposition of ammonium perchlorate(AP)was analyzed by differential scanning calorimetry(DSC).The mixture of nano SrCO₃and AP was calcined in muffle furnace at 350?and 500?for 1h respectively.The product after calcination was characterized by XRD.The mechanism of action of nano SrCO₃ was studied.The results showed that nano SrCO₃ had no effect on the crystal transformation and low-temperature decomposition of AP,and could be decomposed at high temperature Compared with SrCO₃,adding nano SrCO₃ can delay the peak temperature of AP decomposition by 3.22?.As the particle size and specific surface area of nano SrCO₃become smaller,the contact area between Nano SrCO₃ and AP increases.Nano SrCO₃ is easy to react with HCl O₄,the product of AP decomposition at low temperature,to produce more stable substance Sr(Cl O)₂,which can improve the peak temperature of AP decomposition to a greater extent,so as to better inhibit AP decomposition at high temperature.(3)Nano SrCO₃/quaternary ammonium salt composite particles were prepared by solvent-free method,and characterized by SEM and XRD.The results show that the characteristic peaks of raw material and SrCO₃ can be seen in the XRD diagram of nano SrCO₃/quaternary ammonium salt composite particles,and nano SrCO₃ tightly adsorbed on the surface of quaternary ammonium salt particles to form composite particles.(4)The effect of nano SrCO₃/quaternary ammonium salt on the thermal decomposition of ammonium perchlorate(AP)was analyzed by DSC.The results show that compared with nano SrCO₃/quaternary ammonium salt mixture,nano SrCO₃/quaternary ammonium salt composite particles can increase the peak temperature of AP decomposition by 7.61?,and nano SrCO₃/quaternary ammonium salt composite particles can inhibit AP decomposition more obviously.(5)The nano SrCO₃/quaternary ammonium salt composite particles were applied to the butylhydroxy solid propellant,and the burning rate of the propellant samples was measured by the target line method.The results show that when the mass ratio of quaternary ammonium salt and nano SrCO₃ is 3:10,the composite particles have the best speed reduction effect.Compared with the simple mixture of SrCO₃ and quaternary ammonium salt with the same mass ratio,the composite particles have better speed reduction effect and reduce the pressure index to a certain extent.