1. Tapered Porous Structure in Anodic Aluminum Oxide (AAO) Tubular Membrane using a Two-Step Hard Anodization Process Elkin Mejia February 5, 2008

4. Background: Anodization Electrolyte process used to increase thickness of the natural oxide layer on the surface of a metal Source: Elizabeth Grasing

6. Background: Anodization Anodization ranges: (A) Low Field Anodization (0 to 10 V) (B) Mid-Field Anodization (10-40 V) (C) High Field Anodization (40-150 V)

9. Procedure: Processing Stages Source: Elizabeth Grasing Source: Elizabeth Grasing Main Chamber As-Received Tube After Electro-polishing Addition of Polymer Coating 1st Anodization: (Pore Diameter/ Dimple formation) Barrier Layer Etching 2nd Anodization : Pt.1 (Protective Porous Oxide Layer is produced) Pt. 2 (Membrane Thickness Growth) Removal of polymer Ends Sealed with Parafilm Aluminum Etching Removal of Parafilm

13. Trend Analysis (A) Images of Trials, C(S11) D(S12) ~14 µm ~23 µm

15. Trend Analysis (B) Images of Trials, G(S15) E(S13) ~24 µm ~24 µm

17. Trend Analysis (C) Images of Trials, D(S12) G(S15) H(S16) ~23 µm ~24 µm ~57 µm

18. Parameter/Result Table Parameters Results Trials Stages Electrolyte Concentration Voltage Time Transitional Time (min.) Pd (nm) Mt (µm) C(S11)/D(S12) 1st Anodization 3wt.% 12.5 2 hrs. 2nd Andozation (Part 1) 2.7wt.% 20 30 min. 8 20 14 20 20 23 (Part 2) 2.7wt.% 60 3 hrs. G(S15)/E(S13) 1st Anodization 3wt.% 12.5 2 hrs. 20 24 3 hrs. 20 24 2nd Andozation (Part 1) 2.7wt.% 20 30 min. 20 (Part 2) 2.7wt.% 60 3 hrs. D(S12)/G(S15)/H(S16) 1st Anodization 3wt.% 12.5 2 hrs. 2nd Andozation (Part 1) 2.7wt.% 20 30 min. 20 (Part 2) 2.7wt.% 60 3 hrs. 20 23 4 hrs. 20 24 10 hrs. 22 57