Study On Fabrication Of Redox Hydrogel Super-Thin Film And Its Application For Large-Scale Nanomachining

Major industrial countries have been striving to develop nanomachining in recent years,an indicator evermore standing out in the evaluation of manufacturing capabilities of a nation.Confined Etchant Layer Technique(CELT)invented by Tian Zhao-wu is unique compared to other nanomachining techniques for it realizes nano-scale resolution and precision by adopting stressless chemical etching.This dissertation develops a new nanomachining strategy by employing redox hydrogel super-thin film as the confined etchant layer to lower equipment requirements and process difficulty.However,this strategy demands high quality thin film.The influence of physical and chemical processes in film to etching effect needs to be discussed.In this paper,high quality redox hydrogel super-thin film has been prepared out of substantial technic experiments.With the prepared films,this dissertation carried out systemic investigation over the feasibility of improving material balance using electroosmotic and microfluidics and studied its performance.Large-scale curved surface and micropatterns were formed on copper workpiece with redox hydrogel super-thin film,making large-scale nanomachining possible with macroscopical equipments and tools.Chapter 3 discusses the preparation of high quality large-scale(?50 mm)uniform redox hydrogel super-thin film.Spin-coating process was optimized after plenty of technic experiments.The influence on redox hydrogel thin film morphology in spin-coating process was investigated by changing solvent,proportion,mass fraction and concentration of cross-linking agent.The experimental results are as follows:(1)Wettability and stability of carbon film electrode surface were promoted by plasma treatment;(2)Non-volatile solvent and limited concentration of cross-linking agent were effective to reduce defect and improve surface quality of redox hydrogel thin film in spin-coating process.Finally,,the defect free large-scale redox hydrogel super-thin film was fabricated with flexible thickness.Chapter 4 studies nanofabrication of large-scale(?50 mm)curved surface on copper workpiece by using high quality redox hydrogel super-thin film prepared previously.The etching effect was investigated by altering different electrochemical methods and employing electroosmotic and microfluidics.The experimental results demonstrated:(1)Redox reaction of thin film was controlled by cyclic voltammetry with slow sweep speed(1 mV·s-1),which helps the electromigration of Cu2+ from thin film.Therefore,copper surface was etched continuously by redox hydrogel super-thin film in nanometer precision,and the structure fitted to tool electrode was fabricated on workpieces;(2)Material balance was improved by electroosmotic,which generated copper self-corrosion because of bipolar electrochemistry;(3)It was proved that microfluidics had the ability to ensure the water supply in redox hydrogel thin film and accelerate migration rate of reaction products,as well as apply to potentiostatic etching process and improve processing efficiency.The etching rate was promoted to 125 nm·h-1 in potentiostatic machining with 1 ?l·min-1 electrolyte injected in experiments.In chapter 5,different electrochemical methods,like cyclic voltammetry and potentiostatic method were explored in fabricating micropatterns on copper surface preliminarily.The experimental results indicated that the micropattern which is similar with mold electrode was fabricated on workpiece surface,but the structure on workpiece didn't have distinct characteristics in the z-dimension.Machining error was greater than 9.25%,because workpieces were also etched by Cu2+/Cu+ in micropatterning.However,surface quality of workpiece was also influenced by copper oxide formed on surface due to water undersupply in etching process.