Preparation And Charactristics Of Composite Particles Of Metal-Organic Framework With Potential For Wideband Attenuation

With the rapid development of multi-mode composite guided weapons,our military targets face increasingly severe threat.Passive jamming smokescreen materials make one photoelectric countermeasure mean for protecting our targets by strong spectrum adaptability,simple operation,high efficiency and lower cost,which possesses unique advantages against photoelectric guided weapons.Therefore,the development of wide spectrum attenuation smokescreen materials with wide interference frequency band and good interference effect has become an urgent problem to be solved.Therefore,in this work,a metal-organic framework with large specific surface area,small density and controllable structure was selected as the precursor.Through in-situ pyrolysis of the machine frame particles,a variety of metal-carbon composite particles were obtained,and their electromagnetic attenuation properties from the UV to near-mid-far infrared spectra and microwave bands were studied.1.ZIF-67 was synthesized as precursor and pyrolyzed at 400℃,600℃and 800℃,respectively,to obtain Co@C-400,Co@C-600 and Co@C-800 composite particles.The results show that Co@C-800 has better anti-reflection and extinction properties,with an average reflectivity of only 3.69%in the range of 200-2500 nm and an average mass extinction coefficient of 2.61 m~2/g in the range of 2.5-25μm.However,ZIF-67 has better microwave absorption characteristics,with an effective absorption bandwidth of 5.36GHz and a maximum reflection loss of-27.44 d B at a thickness of 2.6 mm.2.MIL-88B was prepared by solvothermal method and annealed at 400℃,600℃and 800℃respectively to obtain three different pyrolysis products Fe@C-400,Fe@C-600 and Fe@C-800.It is found that the average reflectivity of Fe@C-800 is only 10.14%in the 200-2500 nm band,and possess a high photothermal conversion efficiency,with an average mass extinction coefficient of 2.63 m~2/g at 2.5-25μm.However,the absorption properties of the four Fe@C composite particles are not good in the microwave band.Fe@C-400 has a maximum reflection loss of-7.93 d B at a thickness of 2.4 mm.In addition,it is found that in-situ pyrolysis can improve the absorption properties of MOFs materials in UV-far infrared band,but is not conducive to microwave absorption.The conclusion provides reference for the development of new wide spectrum attenuation materials.