Study On The Construction Of MOFs-based Composites And Their Thermal Decomposition Catalysis Of AP

Ammonium perchlorate?AP?is a strong oxidant widely used in propellants.Its thermal decomposition characteristics will significantly affect the propellant's combustion performance.How to screen and prepare excellent performance catalysts to improve the thermal decomposition characteristics of AP,such as high decomposition temperature and slow decomposition speed,is a research hotspot in the field of propellants.In this paper,three metal-organic frameworks?MOFs?materials were designed and prepared,and they were combined with graphene,carbon nanotubes and other carbon nanomaterials to form MOFs@carbon nanomaterial composites.The effects of MOFs-based materials on AP thermal decomposition and impact sensitivity?safety performance?were systematically investigated,and the catalytic mechanism was discussed.The main contents are as follows:?1?Cu?Zn?Co were used as metal ions,and appropriate ligands were selected.Cu-MOF,Zn-MOF and Co-MOF were prepared by solvothermal method and improved diffusion method.The morphology and structure of samples were characterized by scanning electron microscopy?SEM?,X-ray diffraction?XRD?,Energy dispersive spectroscopy?EDS?,Specific surface area test?Brunauer-Emmett-Teller,BET?,it is found that all three materials had a regular crystal structure,and all of them with a large specific surface area.The differential catalytic calorimetry?DSC?and thermogravimetric analysis?TG?were used to test the thermal catalytic performance of MOF on AP.When the mass ratio of MOFs and AP was 5:95,the decomposition peak temperature of AP could advance from 409.7oC to 345.5oC,and increase the apparent decomposition heat from 576 J·g^-1 to 2033 J·g^-1.All three materials had a good catalytic effect on the thermal decomposition of AP,and Co-MOF material showed the best catalytic effect.The impact sensitivity test results showed that the addition of MOFs materials made the impact sensitivity special height value changes within the range of 10%,indicating that the MOFs materials have no harmful effects on the mechanical safety of AP.?2?Graphene oxide?GO?and reduced graphene oxide?rGO?were prepared by redox method,and the samples were characterized by SEM and XRD.The effects of carbon nanomaterials such as graphene oxide,graphene,carbon nanotubes,and hydroxylated carbon nanotubes on the thermal decomposition properties of AP were systematically studied by DSC.It was found that all the four carbon nanomaterials had a certain effect on the thermal decomposition performance of AP.As its content increased,the decomposition peak temperature of AP significantly decreased,and the apparent decomposition heat also increased,and it was mainly because of the high surface area characteristics of carbon nanomaterials and their good electrical conductivity and heat transfer performance.?3?Adding the same amount of carbon nanomaterials during the MOFs synthesis process to prepare eight kinds of MOFs@carbon nanomaterial composite particles.The composite particles were characterized by SEM,XRD,EDS,BET,Fourier Transform Infrared Spectrometer?FTIR?,DSC and TG were used to test the thermal catalytic performance of the composite particles on AP,and the impact sensitivity of these composites were also tested and analyzed.It was found that all kinds of MOFs@carbon nanomaterial composite particles had a catalytic effect on AP thermal decomposition,when the mass ratio of composite particles to AP is 5:95,the decomposition peak temperature could advance to 298.8oC;the apparent decomposition heat could increase to 2185 J·g^-1,and the activation energy could decrease to105.42 kJ·mol^-1.The thermal catalytic effect of MOFs@carbon nanomaterial composite particles on AP are significantly better than using MOFs or carbon nanomaterials alone,indicating that MOFs materials and carbon nanomaterials have a synergistic catalysis effect during the thermal decomposition of AP.The addition of MOFs@carbon nanomaterial composite particles made the impact sensitivity special height(H₅₀)of AP slightly improved,which is conducive to improving the safety performance of AP energetic composite system.