Hong Qiang Nian

Preparation and Properties of 3mol%YF 3 -CaF 2 Nanopowder

Nano-sized 3mol%molYF3-CaF2powder was prepared by co-precipitation method, the prepared powder and sintered ceramic was characterized by XRD and SEM technologies. Results clearly demonstrated that appropriate calcination temperature of 3mol%molYF3-CaF2 composite was below 500°C, and when the YF3-CaF2 ceramic sintering temperature was 900°C, the YF3was uniform doped in CaF2 ceramic successfully and the grain growth was very good.

Evaluation of the Corrosivity of CaF 2 in Hot Water and 10mol%HF Solution

Evaluation the corrosivity of CaF2 in hot water and 10mol%HF solution was studies.Theprepared powder and sintered ceramic was characterized by XRD and SEM technologies. we could conclude that impurities (such as CaO and CaCO3) effected the porperties of CaF2, the grain size is smaller, the corrosion resistance is lower. The CaF2 of corrosion resistance was stronger in HF solution than hot water.

Preparation and Properties of CaF2 Nano-Powder

CaF2 nano-power was prepared by direct precipitation methods with Ca(NO3)2 and KF as raw materials. The influences of presintering temperature and sintering temperature on the particle size and distribution of CaF2 nano-power were studied by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM). This study provided an experimental method for preparation of CaF2 nano-power. The results show that the best presintering temperature of CaF2 nano-power is 500°C and the best sintering temperature of CaF2 ceramic is 900°C.

Microstructures and Properties of Typical Zirconia Tubes for the Determination of Oxygen Content

The measurement of oxygen content in liquid iron and steel has been a challenge for decades and there have been many attempts to develop oxygen sensor to adjustment the smelting process on the basis of the probe for monitoring oxygen dissolved in molten liquid. However, there was still not a common standards of zirconium tubes about domestic product, which limited their application and improvement This work selected several domestic enterprises oxygen measuring half-cell system to study the relationship between the physical properties and microstructure at room temperature. Furthermore, we also analyzed about the typical performance of the domestic Oxygen content products, which would be beneficial to test and improve the quality of domestic products. Keywords: zirconia tubes, oxygen content, oxygen sensor

NiO Sensing Electrode for NOx Detection at High Temperature

Mixed-potential-type NO2 sensor based on yttria-stabilized zirconia(YSZ) with NiO sensing electrode was prepared by the screen-printing technique and its physical characteristics were studied by the X-ray diffraction and scanning electron microscope. The response of electromotive force (EMF) and complex impedance of the sensor were tested under different NO2 concentrations and temperatures. The results show that, at the range of 550–750 °C, the EMF values are negative and almost linear to the logarithm of NO2 concentration. But the sensitivity of the sensor and the amplitude of the EMF response to NO2 concentration both obviously decrease with the increase of the work temperature. In addition, the semicircular arcs of the complex impedance spectra shrink regularly with a raise of NO2 concentration at 600 °C.

Corrosion Behavior of ZrO2-Mo Composite in Na2SO4 Solution

Due to the excellent mechanical properties, ZrO2 was widely used as structural material in multi-industry, such as chemistry, power, biology, metallurgy and so on. The complex working environments require better properties. Besides, thermal shock resistance and corrosion resistance are the most important properties that we need to concern. In this work, ZrO2-Mo composites were synthesis with pressureless sintering method under vacuum environment. The corrosion behavior of ZrO2-Mo in 1 mol/L Na2SO4 solution was investigated. The corrosion experiment was performed in 80°C hot solution for 5, 10, 15 and 20 hours, respectively. The results showed that the composites had good corrosion resisitance in hot Na2SO4 solution. The microstructures were also studied to reveal the corrision behavire of the composite.