Study on Preparation Technology of Porous Pure Iron by Zone Melting in Nitrogen Atmosphere 在线阅读 下载PDF
Author of the article:LIU Endian;LI Zaijiu;LIU Chen;JIN Qinglin
Author's Workplace：Faculty of Materials Science and Engineering,Kunming University of Science and Technology,Kunming 650093,China;Faculty of Civil Aviation and Aeronautics,Kunming University of Science and Technology,Kunming 650500,China
Key Words：double-scale pores zone melting method porous iron nitrogen atmosphere
Abstract：Lotus-type porous pure iron was successfully prepared by zone melting method with using nitrogen instead of hydrogen as working gas. The results show that in addition to the macro cylindrical pores(150~600 μm), uniform spherical pores(0.15~12.00 μm) are found in the microstructure. The diameter of spherical pores decreases and the number of spherical pores increases with the increase of pressure. The phase diagram of Fe-N indicates that there are two significant differences in nitrogen solubility during solidification and subsequent cooling of pure iron. The cylindrical pores are caused by the precipitation of susaturated nitrogen during the transition from liquid to solid phase, and the spherical pores are caused by the poor nitrogen solubility during the transition from austenite to low temperature ferrite. Based on Sewert’s law and ideal gas formula, two kinds of porosity models are established, and the predicted values are in good agreement with the experimental measured ones.
