| VO2(M)is a kind of thermochromic material with excellent performance and has wide application prospect.There are still some problems in the intelligent control of VO2(M)thermochromic performance:mainly reflect in the aspects of relative low visible light transmittance,narrow infrared modulation and poor visualization with monotonous color.How to resolve above problems is always the research hotspots and key points in the field of nanomaterial science and technology for a long time.In this thesis,the structure,thermal phase-change and dynamic thermal management performance of VO2(M)nanoparticle composite films were optimized by using the strategies of composite film,nanoparticle’s coating and nano-thermochromism,which lays a certain foundation for the application of VO2(M)in smart windows and intelligent thermal control of spacecraft.NiCl2-CE ionic liquid analogs solution was prepared by heating and stirring.It was found that the liquid shows a significant thermochromic performance with a yellowgreen color at low temperature and blue-green one at high temperature.VO2(M)-NiCl2CE-PVDF composite films were prepared and the luminous transmittance(Tlum))and solar regulation efficiency(ΔTsol)of the 200 μm composite films can reach 68%and 13.6%,respectively.The color of the composite films changes from brown gray to bluegreen before and after the phase transformation,and the visualization performance of the composite films is significantly improved.VO2(P)@SiO2 core-shell nanoparticles were synthesized in one step by TEOS hydrolysis VOOH nanoparticles for the first time.The transformation from VO2(P)@SiO2 core-shell nanoparticles to VO2(M)@SiO2 core-shell nanoparticles was realized by vacuum annealing.It was found that SiO2 coating effectively inhibits the particle growth and agglomeration of VO2(M)nanoparticles during high temperature heat treatment,and high temperature heat treatment can improve the crystallinity of VO2(M)nanoparticles.Reveals the dependence of the size and crystallinity of VO2(M)nanoparticles on the peak position and intensity of local surface plasmon resonance.It was found the the optimal Tlum and ΔTsol of VO2(M)@SiO2 nanoparticle composite films can reach 38%and 18.9%,respectively.Pure α-VOOH nanospheres and y-VOOH nanosheets had been prepared by hydrothermal method using V2O5 as raw material,and he transformation from α-VOOH nanospheres to VO2(M)nanospheres was realized by adjusting the annealing temperature.The transformation from y-VOOH nanosheets to VO2(M)nanosheets was realized by adjusting the pressure of annealing.It was found that VO2(M)nanosheet composite films have high reversible transmittance modulation in near-infrared to midinfrared band,and the modulation amplitude can reach 65%in thewavelengthof 1900-3500nm,while the infrared transmittance modulation of VO2(M)nanospheres composite films is only 45%in the wavelength of 1900～3500nm.The different infraed modulation ability between VO2(M)nanospheres and nanosheents is well-explained based on the theory of plasma resonance.Triple-layer Ag/SiO2/VO2(M)intelligent thermal control coating was designed and constructed.Ag layer is the reflective layer,SiO2 is the light transmission interval layer and VO2(M)is the thermal control layer.It was found that the thermal control coating has a reversible dynamic emittance modulation,the emittance at low temperature(εL)can be as low as 0.07,while the emittance at high temperature(εH)can be maintained at 0.59,and the emittance modulation(Δε)can reach 0.52.Based on the above parameters,through the simulation of the surface temperature of an insulated spherical shell,it was found that the central position of the spherical shell maintains a low temperature under solar irradiation and the highest temperature is only 428.57 K.The spherical shell has a good insulation effect under low temperature,and the lowest temperature is mere 245.16 K.The simulation is basically consistent with the experimental results. |
PDF Full Text Request