Fabrication of Porous Copper with Directional Pores by Continuous Casting Technique Through Thermal Decomposition of Hyd
- PDF / 1,425,591 Bytes
- 7 Pages / 593.972 x 792 pts Page_size
- 66 Downloads / 233 Views
INTRODUCTION
HOLEY materials are defined as porous materials, which are mainly characterized by porosity.[1] The porous materials with high porosity and low density are called foamed materials, which resemble bubbling materials such as soap. Cellular materials look like honeycomb, whose porosity is also high and the density is low. The holey materials, whose porosity is less than 70 pct, are usually called porous materials. Depending upon the shape of the pores, isotropic and anisotropic materials are classified. The former has rather isotropic spherical pores, while the latter has cylindrically elongated pores aligned in one direction and looks like lotus root and wood, so-called as lotus[2] and gasar materials.[3] The porous and foamed metals exhibit various characteristics such as an inherent low density and large surface area. These metals should be applicable as lightweight materials, catalysts, electrodes, vibration and acoustic energy damping materials, impact absorption materials, etc.[1] Different from foamed and cellular metals, lotus and gasar metals show peculiar features originating from their anisotropic pore morphology. The gas solubility difference between liquid and solid is utilized for fabrication of lotus metals; when the melt TAKUYA IDE, formerly with The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan, is now General Manager, Lotus Alloy Co., Ltd., Umeda1-1-3-267, Kitaku, Osaka 530-0001, Japan. AKIHIRO TSUNEMI, formerly Graduate Student with The Institute of Scientific and Industrial Research, Osaka University, is now a Researcher with the DMG Mori Seiki Ltd., Iga, Mie 519-1414, Japan. HIDEO NAKAJIMA, Director, formerly with The Institute of Scientific and Industrial Research, Osaka University, is also with The Wakasa Wan Energy Research Center, Tsuruga, Fukui 9140192, Japan. Contact e-mail: [email protected] Manuscript submitted October 20, 2013. METALLURGICAL AND MATERIALS TRANSACTIONS B
dissolved by hydrogen is solidified in pressurized hydrogen atmosphere, insoluble hydrogen precipitates to evolve hydrogen pores in the solid phase.[2] Although the fabrication technique is quite advanced, one large technical barrier remains; high-pressure hydrogen gas must be used. Employing high-pressure hydrogen gas has inherent risks because it may lead to inflammable and explosive accidents if oxygen is mixed. Therefore, a technique that does not require high-pressure hydrogen to fabricate lotus metals is highly desirable. In order to overcome this difficulty, Nakajima and Ide proposed an alternative, but simple method to fabricate such lotus metals by using a thermal decomposition method (TDM) of compound containing gas elements in a non-hydrogen atmosphere under nearly atmospheric pressure.[4] So far Nakajima and Ide carried out the first fabrication of lotus metals through thermal decomposition of gaseous compounds; copper was chosen as a metal. Kim et al.[5] used the same method of TDM to fabricate lotus aluminum. Both investigations adopted the mold casting
Data Loading...
