Hydrothermal Preparation And Characterization Of Antireflection Glass With Gradient Refractive Index

Antireflective glass has wide application potential,such as in the field of automotive,photovoltaic,display,construction and other industries.The theory shows that the gradient index structure is the best choice for the antireflective film to obtain excellent antireflective performance,and the etching method is the most simple and low-cost way to prepare this structure.In this paper,the antireflective glass with excellent performance has been prepared by hydrothermal etching method with a new etching solution composition,in which complex is the main component.The mechanism of etching is studied by comparing the results of etching solution with different complexing ability and by means of various characterization methods.The influence of the experimental conditions is further explored,such as etching temperature,etching time,pH and complex concentration.The preparation process of the antireflective film is optimized.The main results are as follows:1.The effect of complex on glass etching was studied by using sodium hydroxide,disodium hydrogen phosphate and sodium citrate.Experiments show that with the increase of the complexing ability of the etching solution,the transmittance increases,and the reflectivity and haze decrease,while the micro etching hole size of the film surface becomes smaller,and the macro film surface tends to be smoother.The etching solution containing complex can prepare porous film with excellent antireflective performance,and play an important role in regulating the microstructure of the film.Glass with reflectivity～1.0%,haze less than 1.5%and great abrasion resistance has been successfully prepared by using alkaline etching solution with added complex compound C6H5Na3O7.Using the film design software TFcalc and Macleod,the refractive index change in vertical of the glass surface etched by the solution containing C6H5Na3O7 was simulated and calculated.It is found that the integral reflective data of symmetrical cosine index profile(Rsimulation=1.19%)fit the experimental data of the sample prepared by C6H5Na3O7(R=1.08%)quite well.2.By comparing the results of etching solutions with different complexing abilities,the roles of the ions in the etching solution are speculated as follows:H+is used for ion exchange;OH-breaks silicon-oxygen bond;the complex ions tend to combine the metal cations in the glass network,so they are preferentially adsorbed on the surface or bond breaking place of the glass.The preferential adsorption of complex anion blocks the breaking of ≡Si-O-Si≡by OH-,resulting in the decrease of the pore diameter of the surface after etching.In addition,the state of the etched film is also related to the radius of the complex anion.The larger the anion radius is,the stronger the blocking effect is,and it can form a denser gradient porous etching film.The Al3+ ions from AlCl3 play the role of entering the network structure to consolidate the film.3.The mixture of EDTA-2Na and EDTA-4Na was used as the main component of the etching solution.The effects of etching temperature,etching time,pH.concentration of complex and AlCl3 on the experiment were discussed.The experimental results are as follows:a).There is a significant effective etching temperature in the etching reaction.Only when the etching temperature is higher than this value(180℃),the reflectivity of the etched glass can be significantly reduced.b).With the increase of the reaction time,the etched holes become larger,the film surface becomes more loose,the thickness and the haze increase.c).The pH determines the initial concentration of OH-in the etching solution.When the pH is less than 7,there is no obvious change in the sample before and after the etching experiment.However,with the increase of pH,the degree of etching is gradually deepened.d).With the increase of the concentration of complex,the reflectivity,transmittance and haze change regularly.e).With the increase of AlCl3 concentration,the reflectivity of etched glass gradually increases,and the transmittance and haze gradually decrease.The optimized preparation process was obtained.The samples with excellent optical properties and wear resistance can be prepared under the conditions of etching temperature of 180℃,etching time of 8 hours,pH between 7～8,with added 3.8 ml complex and 0.001 mol/L AlCl3(the total amount of etching solution is 120 ml).