Jianding Yu

The extraction of Nd from waste Nd–Fe–B alloys by the glass slag method

We report the use of molten slag materials to extract neodymium from waste Nd–Fe–B magnets. X-Ray diffraction and EPMA studies revealed that the Nd–Fe–B alloys produced by the glass slag method using boron trioxide consisted of α-Fe and Fe2B phases. No Nd-containing phase such as the Nd2Fe14B phase and the Nd oxide phase was found in the resultant alloys. The chemical analyses confirmed that the Nd content in the Nd–Fe–B alloys produced by the glass slag method was less than 0.01 wt.% Nd. On the other hand, the slag materials contained a large amount of neodymium. The Nd in the Nd–Fe–B alloys was successfully extracted by the glass slag method using boron trioxide.

Hybrid electrostatic–aerodynamic levitation furnace for the high-temperature processing of oxide materials on the ground

This article describes a hybrid electrostatic–aerodynamic levitation furnace for the containerless processing and study of oxide materials on the ground. Its operation principle relies on an aerodynamic levitator that allows sufficient electric charge to be accumulated on a sample, due to high-temperature heating, before electrostatic levitation can be effective. The article discusses the concept of this new levitator and presents the proof of the technical feasibility of electrostatically levitating and melting oxide material samples (BiFeO3, 49.5CaO–50.5Al2O3 mol %) in a pressurized atmosphere. In addition, superheating–undercooling cycles can be performed while maintaining an exceptional sample positioning stability along the three directions. Moreover, we report the first vitrification of dielectric oxide material samples (49.5CaO–50.5Al2O3 mol %) using an electrostatic levitation method. The article also discusses the advantages of this facility compared with other existing instruments for the contai...

Thermal Stability and Optical Properties of Er3+ Doped BaTi2O5 Glasses

Er3+ doped BaTi2O5 spherical glasses were prepared using a containerless processing with an aerodynamic levitation furnace. These glasses were found to have high solubility of Er3+ and the substitution ratio of Er3+ for Ba2+ reached 30 %. Differential scanning calorimetry measurements revealed that the glass transition temperature Tg and the crystallization onset temperature Tx shifted to high temperatures and the value of T (= Tx – Tg) increased with substitution of Er3+, indicating that the stability against crystallization improved. We found that these glasses had high refractive indices exceeding 2.1 with low Abbe numbers of approximately 20.

Specifications of a ground-based electrostatic levitation furnace and applications to the study of liquid properties

Abstract From 1997, the National Space Development Agency of Japan (NASDA) metastable research team has studied containerless materials processing to establish undercooled and nucleation processing techniques for oxides and high-melting-temperature metals as a preparation for flying the electrostatic levitation furnace on the International Space Station. This crucible-less facility allows samples to be deeply undercooled while avoiding nucleation on the sample surface. It allows not only precise measurements of the thermophysical properties of molten sample, but also permits material processing from the undercooled state. Of the four levitation techniques (acoustic, electromagnetic, electrostatic, aerodynamic), NASDA has concentrated on the development of an electrostatic levitation system, both for use in the ISS and for fundamental research on the ground. A promising containerless experiment of a ceramic oxide using the electrostatic containerless furnace under the microgravity condition offered by a sounding rocket (TR-IA No. 7) was also carried out in 1998 and is addressed in this paper. A novel aerodynamic levitation system was developed to adopt the drop tube which gave smooth cooling curves for molten Y 3 Al 5 O 12 (YAG) sample.

Containerless Solidification of Undercooled Nd2Fe14B by Electrostatic Levitation Furnace

Containerless solidification of undercooled Nd2Fe14B was investigated using the electrostatic levitation furnace developed by the National Space Development Agency of Japan. Spherical samples with diameters close to 2 mm were laser melted and radiatively cooled in vacuum at rates between 100 K/s and 50 K/s. Two recalescence peaks were observed in the cooling curves. They were respectively attributed to phase segregation of primary Fe and solidification of the Nd2Fe14B () phase. The sample that solidified with the higher undercooling level showed a more refined microstructure and a higher saturation magnetization than that solidified with the lower undercooling level.

Huge Dielectric Constant of Transparent Hexagonal BaTiO3 Obtained by Containerless Processing

Transparent hexagonal BaTiO3 synthesized by containerless processing exhibits a giant dielectric constant ϵ over 100000 with a loss component tan δ of about 0.1 at room temperature. The ϵ showed weak temperature dependence in the 300 to 70 K range and then dramatically dropped by 2 orders of magnitude.

Studies on molten glass sealing in diffusion coefficient measurements using shear cell technique

To develop a shear cell technique for measuring the diffusion coefficient of molten materials with high vapor pressure, molten silica glass was used to seal the vapor leak from the clearance between the cell and the rotating rod. An apparatus was designed to investigate the sealing ability of several molten silica glasses. Using Corning 0211, 7059, and 7740 silica glasses, Ar could be sealed under 150 kPa in the 1100–1500 K temperature range. The corresponding viscosities of the molten silica glasses in the sealing temperature range were 105.3–103.8 Pa s. Based on the results of Ar sealing experiments, the configuration of molten glass sealing was used to seal the As vapor leak in InxGa1−xAs diffusion coefficient measurement experiments. The As vapor leak was successfully sealed and excellent diffusion coefficient measurement data were obtained using the shear cell technique during microgravity experiments carried out on sounding rocket.To develop a shear cell technique for measuring the diffusion coefficient of molten materials with high vapor pressure, molten silica glass was used to seal the vapor leak from the clearance between the cell and the rotating rod. An apparatus was designed to investigate the sealing ability of several molten silica glasses. Using Corning 0211, 7059, and 7740 silica glasses, Ar could be sealed under 150 kPa in the 1100–1500 K temperature range. The corresponding viscosities of the molten silica glasses in the sealing temperature range were 105.3–103.8 Pa s. Based on the results of Ar sealing experiments, the configuration of molten glass sealing was used to seal the As vapor leak in InxGa1−xAs diffusion coefficient measurement experiments. The As vapor leak was successfully sealed and excellent diffusion coefficient measurement data were obtained using the shear cell technique during microgravity experiments carried out on sounding rocket.

Containerless solidification of BiFeO3 oxide under microgravity

Containerless solidification of BiFeO3 oxide has been carried out under microgravity with Electrostatic Levitation Furnace (ELF) aboard on the sounding rocket (TR-IA). It is a first containerless experiment using ELF under microgravity for studying the solidification of oxide insulator material. Spherical BiFeO3 sample with diameter of 5mm was heated by two lasers in oxygen and nitrogen mixing atmosphere, and the sample position by electrostatic force under pinpoint model and free drift model. In order to compare the solidification behavior in microgravity with on ground, solidification experiments of BiFeO3 in crucible and drop tube were carried out. In crucible experiment, it was very difficult to get single BiFeO3 phase, because segregation of Fe2O3 occured very fast and easily. In drop tube experiment, fine homogeneous BiFeO3 microstructure was obtained in a droplet about 300 μm. It implies that containerless processing can promote the phase selection in solidification. In microgravity experiment, because the heating temperature was lower than that of estimated, the sample was heated into Fe2O3+liquid phase region. Fe2O3 single crystal grew on the surface of the spherical sample, whose sample was clearly different from that observed in ground experiments.