Different Aperture Highly Ordered Porous Anodic Alumina Template Preparation And Stability Of The Oxidation Process Additives

The method of anodic aluminum oxide (AAO) is more and more popular in preparingnanomaterials because of its special performance and simple techniques. AAOtemplates were prepared in sulfuric acid and phosphoric acid electrolyte by differentmethods, and the mechanism of oxidation was discussed. Moreover, the additivewhich can keep the process of oxidation steady was investigated.1. The preparation of AAO by constant voltage(1) AAO templates with their diameter from 70nm to 120nm and thickness from25μm to 175μm were prepared in oxalic acid. The diameter and thickness willaccrete with the increasing voltage. The diameter and thickness will also be largerand larger with the increasing temperature, while the regularity will be worse andworse. The consistency of electrolyte also has much influence on AAO.(2) AAO templates with their diameter from 100nm to 300nm were prepared inphosphoric acid. The diameter will accrete with the increasing voltage, and theregularity will be improved. On the contrary, the thickness of the AAO will bethinner and thinner.(3) AAO templates with their diameter from 25nm to35nm and thickness from5μm to 25pro were prepared in sulphuric acid. The diameter and thickness willaccrete with the increasing voltage, while the regularity will be worse and worse.The AAO template will be destroyed when the voltage is high.2. The preparation of AAO by constant current density(1) The diameter and thickness will accrete with the increasing current density inoxalic acid. They will be bigger with the increasing oxidation time, while theregularity will be better. Though regularity will be worse after the current densitygetting a high value, the whole quality is good.(2) The diameter will accrete with the increasing current density in phosphoricacid, but the thickness has the opposite change. The diameter and thickness will bebigger and thicker with the increasing oxidation time, while the regularity will bebetter. After a long time of oxidation, the thickness of the film will stop growing.(3) The diameter, thickness and porosity will accrete with the increasing currentdensity, while pore density drops in sulphuric acid. The diameter and thicknesswill be bigger and thicker with the increasing oxidation time, but after a long timeof oxidation, the thickness of the film will stop growing.3. Add the additive to prepare AAO (1) The regularity will be improved in oxalic acid after adding some ethanol. Thethickness will have a linear relation with the quantity of the ethanol, while thediameter of the pores keeps the value 90nm.(2) The structure of pores will be changed added some ethanol in phosphoric acid.The thickness of the films will have little change when we add some ethanol, butthe regularity will be better after adding the ethanol.4. The research of oxidation mechanism(1) The condition of electrochemistry dissolution by constant current densitymethod is soft. The regularity will not be destroyed because of its low voltage atthe time of the little pores' appearance. So the film will have highly orderedstructure by this method. On the contrary, the condition of electrochemistrydissolution by constant voltage method needs high current density. It will destroythe regularity of AAO, and have bad ordered structure.(2) The capability of dissolving the AAO has changed, because the consistency ofinorganic acid has changed in solvent without water after adding some ethanol.The essence is that can adjust the content of the water, reduce the value of currentdensity and the velocity of oxidization and dissolution. So it will form a kind of highly ordered and thick AAO templates, because of'the soft condition.