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摘要
This paper reviews the recent development of porous metals with directional pores, from the aspects of the solidification principle, fabrication method, properties and applications. This kind of porous metals is fabricated by a directional solidification process in pressurized gas atmosphere, utilizing a metal/gas eutectic reaction (Gasar). By controlling solidification direction, not only lotus-type porous structure but also radial-type porous structure can be produced. The coupled growth of solid/gas phases is discussed by applying a solution procedure similar to that in the classical Jackson-Hunt eutectic growth model. The working window considering hydrogen escape and the formation of directional solidification porous structure has been given. Three fabrication techniques including mold casting, continuous casting techniques and Bridgman-type directional solidification method are introduced. Two new progresses about the fabrication of directionally solidified porous structure are described in details: porous alloy with uniform directional pores and high-porosity directionally solidified porous aluminum. Since directionally solidified porous metals exhibit peculiar physical and mechanical properties such as light-weight, air and water permeability, and anisotropy of thermal and mechanical properties, they are suitable for applications in heat sinks, filters, biomaterials and so on.
- 出版日期2018-5
- 单位清华大学
