Electrolysis: processes – compositions used therein – and methods – Electrolytic coating – Treating substrate prior to coating
Patent
1998-11-02
2000-10-31
Valentine, Donald R.
Electrolysis: processes, compositions used therein, and methods
Electrolytic coating
Treating substrate prior to coating
205213, 205223, 205229, 205324, 205328, 205332, C25D 1116
Patent
active
06139713&
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of forming a porous anodized alumina film in which pores having a predetermined shape are arrayed at a predetermined interval.
BACKGROUND ART
Conventionally, as a porous material having a uniform pore size, a porous anodized alumina film is known. The porous anodized alumina film is a porous alumina film formed on an aluminum surface by anodizing aluminum in an acid electrolyte. As a characteristic feature, pores are self-aligned perpendicularly to the film surface, and the uniformity of the pore size is relatively satisfactory. For this reason, the porous anodized alumina film is expected to be used not only as a functional material represented by a filter but also as a starting structure for the form of various nanodevices.
The industrial applicability of such a porous material is considerably influenced by the regularity of the porous structure (pore shape and array). At this point a porous anodized alumina film formed by the conventional technique does not have a satisfactory regularity. More specifically, the porous anodized alumina film formed by the conventional technique has no independent pores perpendicular to the film surface. In addition, the interval between adjacent pores is not constant, and the pores are not round. As a result, the pore sizes are distributed in a wide range.
Straight and independent pores perpendicular to the film surface are not obtained due to the following formation mechanism of the porous structure of the porous anodized alumina film. At the start of anodizing, pores are formed at random, and some of them preferentially grow to form the porous structure. For this reason, at the early stage of anodizing, the porous structure has no regularity, and the pores are bent.
DISCLOSURE OF INVENTION
Conventionally, as a method of solving this problem, the two-step anodizing method has been proposed (Jpn. Journal of Applied Phisics, Vol. 35, Part 2, No. 1B, pp. L126-L129, Jan. 15, 1996). An oxide film formed by performing anodizing for a predetermined time is temporarily selectively dissolved and removed, and then, anodizing is performed again under the same condition, thereby forming an oxide film having straight and independent pores perpendicular to the film surface. This method utilizes the fact that recesses (concaves) are formed in the aluminum surface by removing the anodized film formed by the first anodizing process, and these recesses serve as starting points of the second anodizing process.
With this method, the perpendicularity, straightness, and independence o f each pore are improved, though the pore array has a predetermined disturbance. For this reason, the pore interval is not constant, and the roundness of each pore is not sufficient.
It is an object of the present invention to provide a method of forming a porous anodized alumina film, which solves the problems in the porous anodized film formed by the above-described conventional method, i.e., t h e low regularity of the pore array and the unsatisfactory roundness and size distribution of pores, thereby regularly arraying the pores at a predetermined interval and improving the pore roundness and pore size uniformity.
The present invention has been made to achieve the above object, and according to the first aspect of the present invention, there is provided a method of forming a porous anodized alumina film comprising forming in advance, on a smooth surface of an aluminum plate to be anodized, a plurality of recesses (recessed portions) having the same interval and array as those of pores of an alumina film to be formed in anodizing, and then anodizing the aluminum plate, thereby forming a porous anodized alumina film in which pores having a predetermined shape are regularly arrayed to have the same interval and array as those of the plurality of recesses.
In the present invention, the recesses are artificially formed in advance in the aluminum plate surface to be anodized at the same interval as that of the pores to be formed in anodizing. With t
REFERENCES:
patent: 4889631 (1989-12-01), Rigby et al.
"Structure and Density of Anodic Oxide Films Formed on Aluminum in Oxalic Acid Solutions" by Ken Ebihara et al., Kinzokuhyomengijutsu, vol. 34, No. 11, 1983, pp. 28-33.
"Fabrication of Gold Nanodot Array Using Anodic Porous Alumina as an Evaporation Mask" by Hideki Masuda et al., Jpn.J. Appl.Phys. vol. 35 (1996) pp. L126-L129, Part 2, No. 1B, Jan. 15, 1996.
"Ordered Metal Nanohole Arrays Made by a Two-Step Replication of Honeycomb Structures of Anodic Alumina" by Hideki Masuda et al., Science vol. 268, Jun. 9, 1995, pp. 1466-1468.
Masuda Hideki
Nakao Masashi
Tamamura Toshiaki
Leader William T..
Nippon Telegraph and Telephone Corporation
Valentine Donald R.
LandOfFree
Method of manufacturing porous anodized alumina film does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of manufacturing porous anodized alumina film, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of manufacturing porous anodized alumina film will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2047304