Ming Sun

Synthesis and characterization of nanometer Ce 0.75 Zr 0.25 O 2 powders by solid-state chemical reaction method

The nanostructure Ce0.75Zr0.25O2 powders have been successfully synthesized by using the mechanically activated solid-state chemical reaction method for the first time, with Ce2(CO)3, ZrOCl2ċ8H2O, and H2C2O4ċ2H2O as raw materials. The structure andmorphology of Ce0.75Zr0.25O2 powders were characterized to be in the single cubic phase and spherical shape via X-ray powder diffraction, transmission electron microscopy, X-ray Photoelectron Spectrometer, and BET surface area testing technique. The average size of particles wasmeasured to be less than 20 nm, and the specific surface area was 85.4m2/g. The TG-DTA investigation was used to reveal the possibly chemical reaction mechanism during the synthesis process. The activity of Ce0.75Zr0.25O2 oxide solution in three-way catalysts was also valued in this work.

Synthesis of Different Nanostructured Zirconia by Mechanically Activated Solid State Reaction

Nanostructured ZrO2 was prepared successfully by mechanically activated solid state reaction. The structural and microstructural of products were monitored using X-ray powder diffraction (XRD), transmission electron microscopy (TEM). The effects of ball milling speed and calcined temperature on products were monitored by XRD. The results of XRD show that the most suitable ball milling speed is 150r/min, and the calcined temperature is 600°C. TEM images show that ZrO2 particles prepare at heating rate of 5°C/min have several advantages in the morphology, spherical shape, narrow size distribution with no hard aggregation, and the particle size is about 15 nm, and at the heating rate of 2.5°C/min, a network structure ZrO2 can be prepared for the first time.

Preparation and Characterization of ZrO2/CNTs by Hydrthermal Method

Nano-compounds of ZrO2/CNTs were prepared by hydrothermal method. The ZrO2/CNTs nano-compounds were characterizated by XRD, TEM, BET and Zeta potentials. The results showed that perfect hydrothermal temperature was 180°C, hydrothermal time was 11h, pH was 9.5. It is showed by the analysis of TEM and Zeta potential, adding surfacant CTBA, the surface of nano-tube and Zr(OH)4 colloids take different charge, and they adsorpt each other. And ZrO2 particles were successfully coated on the CNTs in surface-active agent of CTBA.

Preparation of Water-Based No-Clean Flux for High Temperature Lead-Free Solder

A series of water-based no-clean fluxes composed of an anion/nonion binary surfactant were investigated. The wetting behavior of Sn0.7Cu and Sn3.0Ag0.5Cu on copper with different content of binary surfactant, and the performance of the flux were tested according to the Chinese industry standard of SJ/T 11273-2002 (No-clean liquid Flux). The results showed that the wettability of binary complex was better than that of single surfactant. Two promising fluxes for Sn0.7Cu and Sn3.0Ag0.5Cu solder were selected, respectively. The fluxes showed excellent performance such as halogen-free, less corrosivity, low content of volatile organic compound (less than 5%), high spread rate (over 80%), and high surface insulation resistance (beyond 108Ω). The prepared fluxes meet the requirement of lead-free solder.