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Posted: March 24, 2008
South Korean, German team can mass produce nano-porous films
(Nanowerk News) South Korean engineers said Monday that they have developed a method to mass produce nano-porous films needed to make high quality aluminum and used in other advanced materials.
The technology developed jointly by the Korea Research Institute of Standards and Science (KRISS) and Germany's Max Planck institute is expected to greatly help improve the characteristics of aluminum and be used to advance nanotechnology. The findings have been published in the latest issue of Nature Nanotechnology journal.
Because of its relative lightness and strength, aluminum is used around the world in such products as soda cans, various machinery, automobiles and airplanes.
At present aluminum is subject to a so-called anodising process that covers the material with a fine coat of aluminum oxide film. This film provides strength, anti-corrosive protection and excellent electrical insulating properties.
The anodising process, which leaves 10 billion nano-porous holes within a 1-centimeter-square surface of the film, is created by using high voltage electrical currents and sulfuric acid. This procedure is also time consuming.
"Both hard and mild anodising processes used to make aluminum leave uneven holes that are not perfectly aligned, have microscopic cracks that affect quality, and require considerable electrical power," said Lee Woo, the KRISS engineer in charge of research for the project.
He said the new method called "pulse anodizing" selectively utilizes the pros of both the hard and mild processing to make perfectly even and well aligned nano-porous structure in the coating film. The engineer added this method uses less power and has a shorter production cycle which is a prerequisite for industrial mass production.
The engineer said the finished aluminum product made with pulse anodizing is stronger and of higher quality.
Lee, in addition, said that the aluminum oxide film created in this manner has applications as customized nano-lines and tube structures used in industrial patterning masks, filters and other hightech products.
Nano-materials are one-billionth of a meter in size and are usually in the form of tubes. They are tough and have superior anti-corrosive properties than metal and if they can be controlled, could help make ultra small devices that are very energy efficient. Despite such characteristics scientists have yet to fully perfect ways to control the way they are aligned and their shape.