Study On Dispersion Of Nano Combustion Catalyst In Ultrafine Ammonium Perchlorate

Nano-combustion catalysts are widely used to catalyze ammonium perchlorate?AP?and AP-based propellants.However,the problem of easy agglomeration that caused by small particle size and large specific surface area of nano-combustion catalysts has limited its scope of use and catalytic performance.Although the method of mechanical ball milling and spray compounding can improve the dispersibility of nano-combustion catalyst in ultra-fine AP,the problem of characterization of nano-combustion catalyst in ultra-fine AP remains to be solved.For the first time,the dispersion of nano-combustion catalysts in ultra-fine APs was characterized by UV-visible diffuse reflectance spectroscopy.The specific research contents are as follows:First,we chose the three most commonly used nano-combustion catalysts including of nano-chromium chromite?nano-CuCr₂O₄??nano-copper oxide?nano-CuO?and nano-iron oxide?nano-Fe₂O₃?as a representative,and then controlled the dispersion of nanocombustion catalysts in ultrafine AP by manual grinding and mechanical milling.A series of polydispersity and uniformly dispersed nanocombustion catalyst/ultrafine AP composites were prepared by varying the strength,grinding time and nanocombustion catalyst content.Secondly,the dispersity of nanocombustion catalysts in ultrafine AP was qualitatively and quantitatively characterized by the difference in response of UV-visible diffuse reflectance spectra of different nanocombustion catalysts/ultra-fine AP composites at wavelength?=212 nm.The results show,The UV curve and absorbance of different nanocombustion catalyst/ultra-fine AP composite samples increased with the increase of grinding strength and grinding time during the preparation process,and the dispersibility of the nano-combustion catalyst was improved.The dispersion calculated by the mathematical comparison method was obtained.The uniformity also increases with the increase of grinding strength and grinding time,that is,the dispersion of nano-combustion catalyst in ultra-fine AP is continuously improved,and the qualitative and quantitative analysis results are consistent.In addition,the UV test results of the 2wt%mechanical ball milling for 30 min of nano-combustion catalyst/ultra-fine AP composite sample is consistent with the expected results,confirming the qualitative and quantitative characterization methods of nano-combustion catalysts in ultrafine AP established by UV-visible diffuse reflectance spectroscopy is accurate and feasible,and scientific.Finally,the crystal form,particle size distribution,morphology and thermal decomposition properties of the composites were characterized by XRD,SEM and DSC tests on three nanocombustion catalysts/ultrafine AP composites.The results show that as the grinding time and grinding strength increase during the preparation of the composite,the dispersion of the nano-combustion catalyst increases and the pyrolysis peak temperature of the ultra-fine AP gradually decreases,that is,the dispersion of the nano-combustion catalyst in the ultra-fine AP is positively correlated with its catalytic performance,the better the dispersion of nano-combustion catalyst in ultra-fine AP.The better the thermal decomposition catalytic performance of nano-combustion catalyst for ultra-fine AP,which also verified the accuracy of the dispersive characterization method of nano-combustion catalysts in ultrafine AP in turn.