Preparation And Performance Investigation Of The Spectral Selective Absorbing Coatings Based AAO

This study presents an AAO-based branched pipe structure that possesses layers with high and low porosities,featuring a periodical change.This structure was prepared through anodic oxidation,in which the power source with periodically changed voltage and consequently the step-change current were programmed.This leads to sharp alteration of the porosity and finally the AAO-based photonic crystal oxidation film?with a complete photonic band gap?was achieved.Cu-Ni composite nanoparticles was deposited into the pores of the AAO-based photonic crystal film at an AC frequency of 50 Hz under different conditions.The AAO spectral selectivity absorbing coating was prepared with high absorptance,low emissivity,which has corrosion resistance and high-temperature stability.The preparation process of AAO photonic crystal layer was investigated,and the micro morphology of the photonic crystal layer was studied.The results show that in the system of experiment preparation to explore the position of photonic band gap respectively in the vicinity of 648 nm and 528 nm with Structural color feature AAO photonic crystal.The time parameters of periodic oxidation of AAO photonic crystal band gap was explored,the results show that in the periodic time parameters of t0=1200 s,t₁=40 s,t₂=36.2 s,t₃=24.46 s,t₄=61.42 s,t5=128 s,periodic voltage parameters U1=3.2V,U2=7.0V,U3=5.2V,U4=,3.8V;temperature is 20 25?;the oxidation period under the condition of N=80,the target position in the photonic band gap is near 4000 nm.The samples with the photonic crystal layer in three kinds of AC voltage of 11 V,14 V,17V?RMS?were analyzed,and the results show that the coating surface changes during the deposition and the influence of absorption layer: H+ discharge the negative half cycle of alternating current hole film Bureau of the Ministry of H2 resulting in membrane flaking of partial oxidation,a small amount of the attachment of debris;the absorption layer shows "surface fur" shape,the composite particles of metal nanorod structure can be obtained,but the local current density is too high and the deposition rate too fast,which result in nanorods growth orientation shift rod structure part tilting intertwined,reunion,but the target deposition of metal elements are uniformly distributed;the XRD result show that at high voltage in the solution environment system high Cu+ compounds is difficult to achieved,at low voltage rich OH-is difficult to achieved,and at 14 V CuAl2O4 can be achieved at the pores of theAAO.The voltage,time and temperature of AC deposition were analyzed,which show that the combined effects of temperature on the spectral selective absorbing coating:AC deposition time of 700 s,voltage of 17 V,frequency of 50 Hz,temperature under25?,the solar energy absorption coating with AAO photonic crystal layer structure has highest absorptance is 0.95,emissivity is 0.13,the quality factor is 7.3,which shows a good performance of solar spectrum selective absorption;the blank contrast,composite oxide film coating with photonic crystal structure has a lower thermal emission rate,the target AAO photonic crystal structure of the composite film thermal emission inhibited;AC deposition process with little deposition the increase of temperature,the sample surface concavity becomes larger;the electrochemical test results showed that: the deposition of metal particles that have lower corrosion rate,Compared with the blank sample,the corrosion resistance of the prepared samples is increased,the corrosion resistance of the hydrated sealing on most of the samples increased;under following experiment conditions: 14 V,100 s,50 Hz and 25?,samples with high temperature and good thermal stability were prepared,the deposition of Cu-Ni nanoparticles,CuAl2O4 and Al2O3 constitute the three dielectric composites,CuAl2O4 limits the diffusion of Cu-Ni nanoparticles under high temperature environment in the interface,reduces the oxidation rates,the thermal stability of coating system is improved,In the temperature of 600?,the ?/? of coating quality factor hava a small fluctuation.In this paper we found that under the optimized preparation conditions of 17 V,700 s 50 Hz and 25?,the solar absorptance is 0.95,the heat emissivity is 0.13,and the highest quality factor is 7.3,but the samples have poor corrosion resistance and the high temperature stability is under the expectation;while under the preparation conditions of 14 V,100 s,50 Hz and 25?,the absorptance reached 0.84,the lowest rate of emissivity reached 0.14,and the quality factor is 6,the sample has good corrosion resistance and good high temperature thermal stability.