Study On The Desensitization Effect And Mechanism Of GO And G-C₃N₄ On CL-20 And HMX

As the main component of propellants,explosives and initiating explosive devices,energetic materials have been widely used in military and civil fields.Elementary explosive is an important component of energetic materials.With the rapid development of modern weapons and ammunition,the research of elementary explosive has been paid great attention all over the world.CL-20 and HMX are the excellent elementary explosive in energy performance.However,there is an inherent contradiction between the detonation performance and mechanical sensitivity,which seriously limits the further application of these explosives.Therefore,it is urgent to develop high energy and insensitive composite energetic materials to improve the safety performance.In recent years,the coating technology for energetic material has been proved to be an effective method to balance the contradiction between energy performance and safety requirements.Because of its unique two-dimensional planar structure,GO has been developed in desensitizing CL-20 and HMX.In addition,g-C₃N₄ with excellent thermal stability and nitrogen rich properties is also expected to be used to reduce the sensitivity of explosive crystals and make up for the energy loss.How to improve the interface interaction between coating materials and energetic crystals is still the core challenge and research hotspot in the field of explosive desensitization.Therefore,in this thesis,GO and g-C₃N₄ are used as coating materials,combined with different preparation methods and a series of analytical tests to carry out research on the preparation,characterization and desensitization mechanism of CL-20 and HMX composite materials,which provided a novel basis and perspective for expanding the desensitization application of GO and g-C₃N₄ in explosives.The main work includes the following three parts:(1)Hydrazine hydrate functionalized graphene oxide(r GO)and CL-20 coated samples(CL-20/r GO)were prepared by in situ reduction method.The microstructure of the coated samples was observed by scanning electron microscope(SEM),and the chemical composition was characterized by Fourier transform infrared spectroscopy(FT-IR)and Zeta potential analyzer(Zeta).The content and crystal structure were determined by high-performance liquid chromatography(HPLC)and X-ray powder diffraction(P-XRD).The safety performance was measured by BAM mechanical sensitivity meter(IS/FS)and differential scanning calorimetry(DSC)measurement.Single factor variable method was employed to optimize the conditions of hydrazine hydrate addition,reduction temperature and reduction time in the in-situ coating process.Finally,the coating samples with excellent comprehensive properties were selected.The influence of surface structure characteristics of amino graphene on the desensitization of CL-20 coating was deeply discussed,which showed the amino group in functional graphene was beneficial to promote the effect of r GO on CL-20 coating.The desensitization mechanism of CL-20 by amino graphene was revealed based on above analysis.(2)The surface charge of CL-20 was controlled by polyethyleneimine,and CL-20/PEI,CL-20/GO and CL-20/PEI/GO composites were successfully prepared with graphene oxide by combining water suspension and electrostatic self-assembly method.The morphology and structure properties of the composite were analyzed by SEM test,Zeta potential evaluation,XPS composition analysis,IR and Raman structure characterization,P-XRD crystal determination,HPLC content calibration,mechanical sensitivity test and DSC thermal performance parameter calculation.The CL-20/PEI/GO showed improved thermal stability and reduced mechanical sensitivity.We also proposed the possible desensitization mechanism of graphene to CL-20.(3)Considering the sensitivity and energy balance of energetic materials,the nitrogen rich material g-C₃N₄ was introduced to reduce the sensitivity of HMX and make up for the energy3loss of coated samples.Three kinds of HMX/r GO,HMX/g-C₃N₄and HMX/r GO/g-C₃N₄energetic composites were prepared by in-situ reduction and physical grinding methods.The morphology and safety properties of the composites were analyzed by SEM,Zeta,XPS,FT-IR,P-XRD,DSC and mechanical sensitivity tests.The HMX/r GO/g-C₃N₄ comosite showed excellent thermal stability and mechanical sensitivity.The possible desensitization mechanism of graphene oxide and g-C₃N₄ to HMX was proposed based on the above analysis.