Investigation of the Effects of Pore Widening Times on Oxide Pores on Pure Aluminum in Two-Step Anodic Oxidation Process

Abstract

An anodic oxidation process is a commonly used for surface treatment to improve the surface properties of the metals and their alloys such as aluminum, tantalum, titanium, molybdenum etc. and thereby increase the service life of the specimen parts from these metals. A type of anodic oxidation process with different types and conditions is made in the two-step anodic oxidation process. The two-step anodic oxidation is a process that improves several surface properties, such as increasing the corrosion resistance by forming a continuous layer on the surface of a suitable metal such as aluminum. In a two-step anodic oxidation process, which has a more regular pore array than  one-step anodic oxidation, nanotechnology applications have been rapidly developing and with the potential production of various nano-tubes and nano-wires. In this study, the two-step potentiostatic anodic oxidation process on pure aluminum surface was investigated. For this purpose, electrolytically polished samples were anodized at 0,3 M oxalic acid solution at 40 V constant voltage for different times and were subjected to pore expansion in 0.1 M phosphoric acid solution. The current density time graphs obtained during anodic oxidation processes at constant voltages are important for the reproducibility of the anodic oxidation process. The properties of the anodic alumina in the porous structure obtained after pore expansion at different times (0, 30 and 60 minutes) and the average pore diameters were examined by SEM analysis. After the surface investigations, it has been determined that pore arrays become smooth and pore diameters increase depending on an increase in pore widening time. Depending on the desired processes, the fabrication of nanowires/tubes with different sizes can be carried out as desired uniform and homogeneous nanostructures.

Keywords

• Pore diameters,Pore widening,, Pure Aluminum,Two-step anodic oxidation

Saf Alüminyuma Uygulanan İki Aşamalı Anodik Oksidasyon İşleminde Por Genişletme Süresinin Oksit Porlar Üzerindeki Etkilerinin İncelenmesi

Öz

Anodik oksidasyon işlemi alüminyum, tantalyum, titanyum, molibden vb. metal ve alaşımlarının yüzey özelliklerini geliştirmek ve böylece bu metallerden üretilen parçaların servis ömürlerini arttırmak için yaygın bir şekilde kullanılan bir yüzey işlemidir. Çok farklı türlerde ve koşullrda yapılan anodik oksidasyon işleminin bir çeşiti de iki aşamalı anodik oksidasyon işlemidir. İki aşamalı anodik oksidasyon işlemi, alüminyum gibi uygun bir metalinin yüzeyinde sürekli bir tabaka oluşturarak korozyon direncini arttırma gibi birçok yüzey özelliğini geliştiren bir işlemdir. Tek aşamalı anodik oksidasyona göre daha düzenli bir por dizilimine sahip olan iki aşamalı anodik oksidasyon işleminde, nanoteknoloji uygulamaları çok hızlı bir gelişim göstermiş ve bununla beraber çeşitli nano-tüpler ve nano-tellerin potansiyel üretimleri yapılmaktadır. Bu çalışmada, saf alüminyum yüzeyinde iki aşamalı potansiyostatik anodik oksidasyon işlemi incelenmiştir. Bu amaçla elektrolitik olarak parlatılan numuneler 0,3 M oksalik asit çözeltisinde 40 V sabit gerilim değerinde farklı sürelerde anodize edilen numuneler 0,1 M fosforik asit çözeltisinde por genişletme işlemine tabi tutulmuştur. Sabit geriilim değerinde yapılan anodik oksidasyon işlemleri sırasında elde edilen akım yoğunluğu süre grafikleri anodik oksidasyon işleminin tekrarlanabilirliği açından önem arz etmektedir. Farklı sürelerde (0, 30 ve 60 dakika) yapılan por genişletme işleminden sonra elde edilen gözenekli yapıdaki anodik alüminanın homojenliği ve ortalama por çapları gibi özellikleri yüzeyden yapılan SEM analizleriyle incelenmiştir. Yapılan incelemeler sonunda artan por genişletme süresine bağlı olarak por dizilimlerinin düzgünleştiği ve por çaplarının arttığı tespit edilmiştir. İşlemlerin arzu edilen şekilde yapılmasına bağlı olarak farklı boyutlarda sahip nanotellerin/tüplerin üretimi istenilen düzgün ve homojen nanoyapılar şeklinde gerçekleştirilebilecektir.

 

Anahtar Kelimeler

• Por çapları,Por genişletme,Saf alüminyum,İki aşamalı anodik oksidasyon

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