Study On Functionalization Of Metal Nanopowders Prepared By Macros

With the advantages of excellent strength,heat,sound,light,electromagnetic properties,metal and metal oxide nanopowders have a wide application and broad prospects for development in solid propellants,explosives,microwave absorbing materials,antibacterial textiles,self-repairing lubricating oil,powder metallurgy,solution source,environmental protection and other fields.Nowadays,the development of nanomaterials is guided by the application.Many methods have been developed for the preparation of metal nanopowders,such as electro-exploded wire,evaporation-condensation method,sol–gel method,sputter method,ball milling.However,there are many problems,such as low yield,easy reunion,non pure nanoscale,high cost and so on in these methods.It is difficult to meet the requirements of application.Solid propellants and microwave absorbing materials are of great strategic significance to national security.Antibacterial textiles have an important application in both military and civil fields.For these reasons,aluminum,iron,cobalt,magnetite and copper nanopowders were prepared in large quantities by metal nanopowder macro fabrication technology?MPNP?,and their functional applications in solid propellants,microwave absorption and antibacterial textiles were studied.The main contents and results are as follows:1.Studied the preparation of Al nanopowders and their application in hydroxyl Terminated Polybutadiene?HTPB?propellant:Through MPNP,the NP-V nano powder production equipment has been developed,and the monodisperse and core-shell structure Al nanopowders were produced at the rate of more than 200 g/h.The prepared Al nanopowders have the following advantages:Low initial oxidation temperature(T_on=509°C),high energy release capacity?S/?m*=19.98 kJ/g?,the electrostatic spark sensitivity,the friction sensitivity and the impact sensitivity are almost equivalent to the micron aluminum powder?FLQT1?and good compatibility with HTPB.The Al nanopowders can increase the burning rate of HTPB propellant and reduce the pressure index.With the increase of the content of Al nanopowders,the increase of the burning rate increases greatly,and the pressure index is also greatly reduced.The pressure index of 3%Al nanopowders propellant was reduced from 0.54 to 0.31,and 42.65%was reduced.The pressure index of 8%Al nanopowders was reduced to 0.20,and 63.6%was reduced.2.Studied the preparation and microwave absorption properties of Fe nanopowders and Fe/carbon porous structure nanofibers:Core/shell structure Fe nanopowders with good dispersibility were prepared by the NP-V nano powder production equipment.The Fe nanopowders were added to PAN/oil/DMF emulsion,and the Fe/carbon porous nanofibers with three-dimensional cross-linked network structure were prepared by electrospinning.The effect of geometric effect on microwave absorption performance was studied by MATLAB software,and the matching thickness at different frequencies was calculated.Under the combined action of impedance matching,dielectric loss,magnetic loss,high attenuation constant and geometric effect,Fe/carbon porous nanofibershave excellent microwave absorbing properties.The reflection coefficient?RL?of the Fe/C porous structure nanofibers is-56.6 dB at 4.96 GHz with the thickness of 4.29 mm.Moreover,a good absorption performance?RL?-15.0 dB?from 2.00 GHz to 18.00 GHz is obtained under the matching frequency and matching thickness.3.Studied the preparation and microwave absorption properties of Co nanopowders and Co/carbon porous structure nanofibers:Core/shell structure Co nanopowders were prepared by the NP-V nano powder production equipmenthas.Co/C porous nanofibers with excellent microwave absorbing properties were prepared by electrospinning.The RL reaches-63.6 dB at 5.28 GHz with a thickness of 5.21 mm and the absorption bandwidth?RL?-10.0 d B?is 4.20 GHz.Under matching frequency and matching thickness,the RL?-10.0 dB from 2.24 GHz to 18.00 GHz.4.Studied the preparation and microwave absorption properties of magnetite?Fe+2Fe2+3O₄?nanopowders and magnetite/carbon porous structure nanofibers:Well dispersed magnetite nanopowders were prepared by the NP-V nano powder production equipment.Three-dimensional cross-linked network structure magnetite/carbon porous structure nanofibers were prepared by electrospinning.The composites have excellent microwave absorption properties,especially at high frequency.The RL reaches–59.0dB at 9.36 GHz with a thickness of 2.35 mm.The RL value can also reach-54.5 dB at15.52 GHz with a thickness of only 1.46 mm and the absorption bandwidth?RL?-10.0 dB?is about 4.32 GHz.Furthermore,a good absorption performance?RL?-30.0dB?from 8.20 GHz to 18.00 GHz with the thicknesses less than 2.66 mm is obtained under matching frequency and matching thickness.5.Studied the preparation of copper nanopowders and their antibacterial properties in textiles:Well dispersed copper nanopowders were prepared by the NP-V nano powder production equipment.The Cu nanopowders were added to the dye,and the Cu nanoparticles were attached to the surface of the fiber while the cloth is dyed.As the Cu nanopowders have large specific surface area,it has excellent antibacterial properties for both Gram-negative and Gram-positive bacterium.When the addition amount of Cu nanopowders is more than 0.3%,the bacterial inhibition rates of Escherichia coli and Staphylococcus aureus are all higher than 98.25%,and the rate of bacterial inhibition is 100%when the addition amount of Cu nanopowders is 1.0%.The Cu nanopowders have excellent antibacterial properties for antibacterial textiles and have a great industrial application prospect.