Papers by Author: Dong Hua Yang

Abstract: Ti/Al(Ti-50at.%Al) composite powders were prepared by high-energy ball milling followed by reaction sintering heat treatment at 550°C ~ 650°C for 2 hours. Mechanical alloying of TiAl had been performed in a high energy plant ball after different milling times and pre-sintered at different temperatures. The particle sizes of Ti/Al powders were analyzed by scanning electron microscopy (SEM). X-ray diffraction (XRD) analysis was performed for microstructural characterization. The results show that microstructural and morphological changes of high energy milled powder are studied as a function of milling time. Over 600°C TiAl powders are completely alloyed by being sintered at different temperatures. The powders are mainly composed of γ-TiAl as well as a small amount of AlTi3. The TiAl alloy powders of high energy ball mill/2h and sintered at 650°C/2h get plasma spheroidization. Spheroidizing powders with fine texture, γ-TiAl and AlTi₃ phase, particle size of 10~40μm are obtained.

Abstract: Nano-Fe₃O₄ magnetic particles were prepared by ultrasonic emulsion method and then were dispersed into water with chitosan or folate as surfactants for biocompatible water-based Fe₃O₄ magnetic fluid. The cubic inverse spinel structure of Fe₃O₄ nanoparticles were analyzed by X-ray diffraction technique (XRD). The saturation magnetizations of different magnetic particles were tested by a vibrating sample magnetometer (VSM). The morphologies of nanoparticles were observed by transmission electron microscope (TEM). The particle size was about uniform 10-20 nm, and their shape was approximately spherical. Meanwhile, dispersity was improved markedly after the surface modification. Comparing to magnetic fluid with chitosan modification, magnetic fluid was coated with chitosan and folate gets higher dispersity and stability when both of them have same saturation magnetizations.

Abstract: In order to increase the magnetic fluids in target-based cancer treatment, the Cu²⁺ has been studied in this study. The Fe₃O₄ and Cu_0.1Fe_0.9O•Fe₂O₃ magnetic nanoparticles were prepared by ultrasonic emulsion method, and then disperse them into water with sodium dodecyl benzene sulfonate (SDBS) as surfactants to make magnetic fluids. The cubic inverse spinel structure of Fe₃O₄ and Cu_0.1Fe_0.9O•Fe₂O₃ nanoparticles were analyzed by X-ray diffraction technique (XRD).The saturation magnetization of Fe₃O₄ and Cu_0.1Fe_0.9O•Fe₂O₃ were 79.55 emu•g^-1 and 75.90 emu•g^-1 by vibrating sample magnetometer (VSM). The morphologies of nanoparticles were observed by transmission electron microscope (TEM). The particle size was uniform 10-20 nm, and their shape was approximately spherical. The Cu_0.1Fe_0.9O•Fe₂O₃ magnetic particle functional group and the surface of particle coated with SDBS have been detected by Fourier Transform Infrared Spectroscopy (FT-IR). The magnetic fluids with a high saturation magnetization and stability have been prepared successfully in this study.