Lee Hsun Lecture Series
Topic: Fabrication, Properties and Applications of Porous Metals with Directional Pores
Speaker: Prof. Hideo Nakajima
The Wakasa Wan Energy Research Center, Emeritus Professor of Osaka University, Japan
Time: 10:00-12:00 AM., (Wed.) Sept. 10, 2014
Venue: Room 403, Shi Changxu Building, IMR CAS
Welcome to attend!
Lotus-type porous metals with long cylindrical pores aligned in one direction are fabricated by unidirectional solidification through pressurized gas method (PGM) and thermal decomposition method (TDM) of gas compounds. The pores are evolved from insoluble gas when the molten metal dissolving the gas is solidified. The nucleation and growth mechanism of the directional pores in metals are discussed with a model experiment of carbon dioxide pores in ice. Three fabrication techniques, mold casting, continuous zone melting and continuous casting techniques, are adopted. The latter two techniques can control the solidification velocity and the last one possesses a merit for mass production of lotus metals. The porosity and pore size are able to be controlled by the solidification velocity and ambient gas pressure, while the pore direction can be controlled by the solidification direction. Not only lotus metals but also lotus intermetallic compounds, semiconductors and ceramics can be produced by this method.
Anisotropy in the mechanical and physical properties is resulted from anisotropic pore morphology. The anisotropic behavior of tensile, compressive and fatigue strength are explained in terms of the dependence of stress concentration on the pore orientation.
Several applications of lotus metals to manufacturing productsare investigated. The unidirectional pores can be utilized for high performance of heat sinks for electronic devices of hybrid, EV cars and super-computers, and also for cooling panels in jet-engine of aircrafts. Vibration damping behavior can be used for golf putter and machine tools. Open pores are useful for dental implants to intrude bone tissue into the pores and fix the implants. Flexilibility of lotus stainless steel wires can be utilized for guide wires of medical instruments. Thus, lotus metals are expected to be used for variousmanufacturing products.
1. H.Nakajima: “Fabrication, properties and application of porous metals with directional pores”, Progress in Materials Science 52 (2007) 1091-1173.
2. H.Nakajima: “Fabrication, properties and application of porous metals with directional pores”, Proceedings of the Japan Academy, Ser. B, 86 (2010)884-899.
3. H.Nakajima: Porous Metals with Directional Pores, Springer Tokyo Heidelberg New York Dordrecht London (2013).
ISBN 978-4-431-54016-8 ISBN 978-4-431-54017-5(eBook)