• Title/Summary/Keyword: PoreWidening

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Nano-engineering of Hybrid Titanium Oxide Structure (TiO2) using Pore-widening Concentration for Enhanced Superhydrophilicity

  • Yeji Choi;Chanyoung Jeong
    • Corrosion Science and Technology
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    • v.23 no.1
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    • pp.41-53
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    • 2024
  • Titanium alloy is gaining attention in the medical industry due to its excellent biocompatibility and osteoconductivity. However, the natural oxide film on the titanium surface is insoluble, resulting in inadequate bone adhesion. Therefore, it is necessary to optimize the contact between biological tissues and implant surfaces, and alter the chemical composition and morphological characteristics of the implant surface. In this study, the anodization method was applied to titanium surface treatment to form a uniform and robust oxide film. Subsequently, a chemical process, pore-widening, was employed to change the morphological characteristics of the oxide film. The concentration of the pore-widening solution was varied at 2, 4, 6, and 8 wt% and the process time was set at 30 and 60 minutes. As the concentration of the pore-widening solution increased the pore diameter of the oxide film increased. Notably, at 6 wt% for 60 minutes, the oxide film exhibited a coexistence of pillars and pores. Based on this, it was determined that surface roughness increased with higher concentration and longer process time. Additionally, the presence of pillars and pores structures maximized hydrophilicity. This study provides insights into enhancing the surface properties of titanium for improved performance in medical implants.

Synthesis of Stepped Carbon Nanotubes in Anodic Aluminum Oxide Templates (알루미나 형틀을 이용한 서로 다른 직경을 갖는 모양을 가진 탄소나노튜브의 합성)

  • Im Wan-soon;Cho You-suk;Choi Gu seok;Kim Dojin
    • Korean Journal of Materials Research
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    • v.14 no.9
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    • pp.664-669
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    • 2004
  • Anodic aluminum oxide (AAO) with pores of various diameter, density, and thickness values was obtained through control of the anodization parameters including voltage, temperature, pore widening time, anodization time, etc. The pore diameter was controlled by a pore widening in an etchant, and alumina templates having stepped nano-channels were fabricated by repetition of anodization and pore widening processes. Stepped carbon nanotubes (CNTs) were then grown on the stepped AAO templates by pyrolysis of acetylene without using the catalyst. High-resolution transmission electron microscopy images revealed that CNTs have a multi-wall structure made of graphite flakes of several nm sizes. The current-voltage characteristic of the sloped and linear CNTs were also examined.

The formation of highly ordered nano pores in Anodic Aluminum Oxide

  • Im, Wan-soon;Cho, Kyung-Chul;Cho, You-suk;Park, Gyu-Seok;Kim, Dojin
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2003.03a
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    • pp.53-53
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    • 2003
  • There has been increasing interest in the fabrication of nano-sized structures because of their various advantages and applications. Anodic Aluminum Oxide (AAO) is one of the most successful methods to obtain highly ordered nano pores and channels. Also It can be obtained diverse pore diameter, density and depth through the control of anodization condition. The three types of substrates were used for anodization; sheets of Aluminum on Si wafer and Aluminum on Mo-coated Si wafer. In Aluminum sheet, a highly ordered array of nanoholes was formed by the two step anodization in 0.3M oxalic acid solutions at 10$^{\circ}C$ After the anodization, the remained aluminum was removed in a saturated HgCl$_2$ solution. Subsequently, the barrier layer at the pore bottom was opened by chemical etching in phosphoric acid. Finally, we can obtain the through-channel membrane. In these processes, the effect of various parameters such as anodizing voltage, anodizing time, pore widening time and pre-heat treatment are characterized by FE-SEM (HITACH-4700). The pore size. density and growth rate of membrane are depended on the anodizing voltage and temperature respectively. The pore size is proportional to applied voltage and pore widening time The pore density can be controlled by anodizing temperature and voltage.

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Preparation of Nano Wire by Anodic Oxidation I. Characteristics of Alumina Nano-Template by Anodic Oxidation (양극산화법에 의한 나노와이어 제조I. 알루미나 나노 템플레이트의 특성)

  • Jo, Su-Haeng;O, Han-Jun;Park, Chi-Seon;Jang, Jae-Myeong;Ji, Chung-Su
    • Korean Journal of Materials Research
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    • v.12 no.2
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    • pp.121-128
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    • 2002
  • Anodic alumina layer can be used as templates for preparation of nano-structured materials, because porous oxide layer on aluminum shows a uniform pore size and a high pore density. In order to find out possibility for template material to prepare nano wire, the effects of the anodic applied potential, anodic time and the temperature of electrolyte on pore diameter of anodic alumina layer were studied using SEM and AFM. The pore diameter of anodic alumina layer increased with applied anodic potential and electrolytic temperature. Especially, the pore diameter of anodic oxide layers formed in chromic acid can be well replicated by widening process in $H_3$$PO_4$solution.

Fabrication of Alumina Membrane Using Anodic Oxidation Process (양극산화를 이용한 알루미나 나노세공 멤브레인의 제조)

  • Im, W.S.;Cho, K.C.;Cho, Y.S.;Choi, G.S.;Kim, D.J.
    • Korean Journal of Materials Research
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    • v.13 no.9
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    • pp.593-597
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    • 2003
  • Anodic aluminum oxide (AAO) membrane was made of aluminum sheet (99.6%, 0.2 mm thickness). The regular array of hexagonal nano pores or channels were prepared by two step anodization process. A detail description of the AAO fabrication is presented. After the 1st anodization in oxalic acid (0.3 M) at 45 V, The formed AAO was removed by etching in a solution of 6 wt% $H_3$$PO_4$+1.8 wt% $H_2$$CrO_4$. The regular arrangement of the pores was obtained by the 2nd anodization, which was carried out in the same condition as the 1st anodization. Subsequently, the alumina barrier layer at the bottom of the channel layer was removed in phosphoric acid (1M) after removing of aluminum. Pore diameter, density, and thickness could be controlled by the anodization process parameters such as applied voltage, anodizing time, pore widening time, etc. The pore diameter is proportional to the applied voltage and pore widening time. The pore density and thickness can be controlled by anodization temperature and voltage.

Development of Fabrication Technique of Highly Ordered Nano-sized Pore Arrays using Thin Film Aluminum (박막 알루미늄을 이용한 규칙적으로 정렬된 나노급 미세기공 어레이 제조기술 개발)

  • Lee, Jae-Hong;Kim, Chang-Kyo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.8
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    • pp.708-713
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    • 2005
  • An alumina membrane with nano-sized pore array by anodic oxidation using the thin film aluminum deposited on silicon wafer was fabricated. It Is important that the sample prepared by metal deposition method has a flat aluminum surface and a good adhesion between the silicon wafer and the thin film aluminum. The oxidation time was controlled by observation of current variation. While the oxalic acid with 0.2 M was used for low voltage anodization under 100 V, the chromic acid with 0.1 M was used for high voltage anodization over 100 V. The nano-sized pores with diameter of $60\~120$ nm was obtained by low voltage anodization of $40\~80$ V and those of $200\~300$ nm was obtained by high voltage anodization of $140\~200$ V. The pore widening process was employed for obtaining the one-channel with flat surface because the pores of the alumina membrane prepared by the fixed voltage method shows the structure of two-channel with rough surface. Finally, the sample was immersed to the phosphoric acid with 0.1 M concentration to etching the barrier layer.

A Study of Pore Formation of AAO Film on Si Substrate with Optimizing Process (Si 기판에 제작된 AAO 박막의 기공 형성 최적화에 관한 연구)

  • Kwon, Soon-Il;Yang, Kea-Joon;Song, Woo-Chang;Lee, Jae-Hyeong;Lim, Dong-Gun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.5
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    • pp.415-420
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    • 2008
  • AAO films were fabricated on two kinds of substrates such as $Al/SiO_2/Si$ and Al/Ni/Ti/Si. To obtain well-aligned AAO film, we optimized process condition for buffer layer, electrolyte and voltage. In the case of oxalic acid, the AAO film with pore size of approximately 45 nm was obtained at voltage of 40 V, temperature of $10^{\circ}C$, oxalic acid of 0.3 M and widening time of 60 min. Then the thickness of barrier is less than 600 nm. In the case of sulfuric acid, the AAO film has pore size of 40 nm and barrier thickness of 400 nm with optimum conditions such as voltage of 25 V, temperature of $8^{\circ}C$, sulfuric acid of 0.3 M and widening time of 60 min.

Fabrication of nanohoneycomb structures and measurement of pore sizes (나노허니컴 구조물의 제작 및 홀 사이즈 측정)

  • Choi, Duk-Kyun;Lee, Pyung-Soo;Hwang, Woon-Bong;Lee, Kun-Hong
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2005.04a
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    • pp.265-268
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    • 2005
  • A new method for measurement of the pore size in a nanohoneycomb structure using atomic force microscopy (AFM) was proposed. Porous type anodic aluminum oxide (AAO) was fabricated as a nanohoneycomb structure to measure the pore size. For measuring pore sizes from AFM images, a criterion was set in porous type AAO. The pore sizes from AFM images were compared with those from SEM images, and the results showed good agreement. The relationship between the pore size and widening time was found to be linear in the range of this study. It was understood as the synchronized effects of the impurity gradient in outer oxide of AAO, mechanical packing and mass transfer increase.

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Structural and Electrical Properties of an Electrolyte-insulator-metal Device with Variations in the Surface Area of the Anodic Aluminum Oxide Template for pH Sensors

  • Kim, Yong-Jun;Lee, Sung-Gap;Yeo, Jin-Ho;Jo, Ye-Won
    • Journal of Electrical Engineering and Technology
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    • v.10 no.6
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    • pp.2364-2367
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    • 2015
  • In this study, we fabricated an electrolyte-insulator-metal (EIM) device incorporating a high-k Al2O3 sensing membrane using a porous anodic aluminum oxide (AAO) through a two-step anodizing process for pH detection. The structural properties were observed by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction patterns (XRD). Electrochemical measurements taken consisted of capacitance-voltage (C-V), hysteresis voltage and drift rates. The average pore diameter and depth of the AAO membrane with a pore-widening time of 20 min were 123nm and 273.5nm, respectively. At a pore-widening time of 20 min, the EIM device using anodic aluminum oxide exhibited a high sensitivity (56mV/pH), hysteresis voltage (6.2mV) and drift rate (0.25mV/pH).

Effect of 2nd Anodization on the Pore Formation for Alumina Nano Templates (알루미나 나노템플레이트의 기공형성에 미치는 2차 양극산화의 영향)

  • Cho, S.H.;Oh, H.J.;Joo, E.K.;Yoo, C.W.;Chi, C.S.
    • Korean Journal of Materials Research
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    • v.12 no.7
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    • pp.533-539
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    • 2002
  • Porous anodic aluminum oxide layer for nano templates was prepared in acidic solutions. In order to investigate effects of 2nd anodization on ordered formation behaviors of the porous oxide layers, electrochemical and microstructural studies were performed, primarily using TEM, FE- SEM, AFM, and Ultramicrotomy. The pore diameter of the anodic oxide layer increased approximately linearly with increasing voltages, and to the contrary, the pore density decreased. It was shown that 2nd anodizing on the cell base after dissolving 1st anodic oxide layer was remarkably effective for forming ordered array of the pores, comparing with the case for 1st anodization only. And for controlling the diameter of pores, widening method by chemical dissolution seemed more practical than by electrochemical methods.