Research On Preparation And Performance Of Nano Alumina Coating

It is very attractive for colloidal particles to be assembled into a crystal structure in micron size.This special complex structure and stable physical and chemical properties give it special functional properties,such as anti-reflection and superhydrophobicity,these characteristics are expected to be successfully applied to the moisture-proof,anti-corrosion and anti-reflection aspects of product packaging.In this work,Al2O3 particles were prepared by combining the sol-gel method and the hydrothermal reaction method and assembled into pyramid-shaped and chrysanthemum-shaped stacked structures.First,the aluminum oxide film was prepared by using Al(NO3)3 and H2NCONH2 as the aluminum source and precipitating agent under the condition of no etching on the single crystal silicon wafer.The Al2O3 film was controlled by changing the time,temperature and filling amount of the hydrothermal reaction.At the same time,by studying the drying time after the sol-gel method,the best conditions for preparing the pyramid-shaped alumina film are explored.In order to study and analyze the overall structure and composition of the pyramidal Al2O3,scanning electron microscope(SEM),energy dispersive spectrometer(EDS),X-ray diffraction(XRD),transmission electron microscope(TEM)and other methods are used.The prepared Al2O3 thin film is composed of a pyramid structure whose base length is in the range of 1-100 ?m.This pyramid structure is mainly composed of nanorods and nanospheres.The average reflectance of the Al2O3 film surface in the visible light range is 17.9%,which effectively reduces the reflectance of the monocrystalline silicon wafer surface.At the same time,the surface contact angle of the film was 42°through water contact angle detection,indicating that the surface of the film is hydrophilic.In addition,This study explored the influence of different aluminum sources on the morphology of the alumina coating,and modified the resulting coating with low surface energy to prepare superhydrophobic surface.Al(NO3)3,Al2(SO4)3,AIF3 and AlK(SO4)2 were used as aluminum sources to prepare corresponding alumina coatings.To explore the influence of different aluminum sources on the morphology and wetting characteristics of Al2O3 coatings,through scanning electron microscope(SEM),laser confocal microscope(LSCM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),Fourier infrared spectroscopy(FTIR),water contact angle test(WCA),etc.The result shows that the anions and cations produced by the hydrolysis of different aluminum sources will produce different surface morphologies.The micro morphology of the Al2O3 coating made with Al2(SO4)3 and AlK(SO4)2 as the aluminum source is a lamellar and a chrysanthemum structure.The chrysanthemum-like Al2O3 has been modified by methyltrimethoxysilane(MTMS)to achieve super-hydrophobicity.In addition,the roughness of the Al2O3 coating sample is not positively correlated with the contact angle.Within a certain range,the contact angle increases with the increase in roughness.In addition to roughness,the micro-nano composite structure is also an important factor in determining the superhydrophobic performance.The modified Al2O3 coating with a micro-nano composite structure has the best superhydrophobic performance,with a contact angle of 159.9±1.5°and a rolling angle of 1.2±0.5°.