Papers by Author: Shu Qi Zheng

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Authors: Yu Xuan Liang, Peng Peng Bai, Shu Qi Zheng
Abstract: Pyrite (FeS2) is an important semiconductor material which shows various excellent optical and electrical properties and extensive applied prospect as a new-type, photoelectrical functional materials. In this study, a low cost and efficient simple hydrothermal two-step synthetic method was given to obtain FeS2 microspheres with 2-3 μm in diameter. The obtained products were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet and visible spectrophotometer (UV-Vis). XRD showed that the synthetic sample consisted of two crystal structures of FeS2, pyrite and marcasite. SEM observation indicated that FeS2 microspheres were well crystallized and had good uniformity. UV-Vis spectrum had a strong optical absorption in the region of 200-400 nm wave length. The reaction temperature had an impact on the size of FeS2 microspheres. A possible mechanism for the size of the FeS2 microspheres generated at high temperature is smaller than that at low temperature is discussed.
Authors: Teng Fang, Shu Qi Zheng, Hong Chen, Peng Zhang
Abstract: The band structures and transport properties of Half-Heusler compounds NbFeSb and NbRuSb were studied using ab initio calculations and the Boltzmann transport equation with constant scattering time approximation (CSTA). Both compounds were identified as good p-type thermoelectric materials because of the combination of heavy and light bands in the valence band maximum (VBM). The Seebeck coefficients for NbRuSb were lower than that for NbFeSb; while the electrical conductivities for NbRuSb were little higher than that for NbFeSb. Consequently, the power factors in the p-type regimes for both compounds were similar at a given temperature. NbFeSb and NbRuSb could be efficient materials for thermoelectric generators based on the results in the present investigation.
Authors: Peng Peng Bai, Yu Xuan Liang, Li Wei Liu, Cheng Shuang Zhou, Shu Qi Zheng, Chang Feng Chen
Abstract: The effect of CO2 on the hydrogen permeation behaviour of carbon steel was investigated in a high temperature and high pressure hydrogen permeation device, through hydrogen permeation test, weight loss test, hydrogen content test, and SEM-EDS. The results showed that the peak value of the hydrogen permeation curves were almost the same with or without CO2, but the hydrogen permeation curve rose sharply, and then decreased gradually to a stabilized current value in H2S/CO2 environment, which was lower than in H2S environment. The corrosion rates and the amount of hydrogen of steel in H2S/CO2 environment were lower than in H2S environment. Therefore, it is considered that CO2 has an effect on the hydrogen permeation in H2S, mainly due to the change of corrosion products.
Authors: Shu Qi Zheng, Chang Feng Chen, Li Qiang Chen, Chun Yu Li
Abstract: The weight-loss method was used to study the effect of H2S/CO2 pressure on the corrosion behaviors of L360QCS in the environments with the existence of elemental sulfur and H2S/CO2. The morphologies, compositions and structure of corrosion products formed at different partial pressures were studied by the means of SEM, EDS and XRD techniques. The results show that the existing of H2S/CO2 increases the corrosion rate sharply and the corrosion rate increase dependence on H2S/CO2 pressure. At low gas pressure the production is mainly cubic FeS crystal while that is square FeS crystal at high pressure.
Authors: Shu Qi Zheng, Chun Yu Li, Chang Feng Chen
Abstract: The accelerated corrosion action of sulfur for carbon steel in wet H2S environment was studied by simulating the actual serviced environment. The weight-loss method, SEM, EDS and X-ray diffraction techniques are used to analyze the corrosion rate, the structure and the composition of the corrosion production formed in the environments. The results show that sulfur aggravated the corrosion sharply in wet H2S environment.
Authors: Shu Qi Zheng, Cheng Shuang Zhou, Li Qiang Chen, Chang Feng Chen
Abstract: After Hydrogen-induced cracking (HIC) test, many hydrogen blisters appeared on the surface of A333Gr6 pipeline steel. The amount of hydrogen blistering depends on the sample location. The amount and area rate of the hydrogen blistering on the surface of A333Gr6 sample near the internal wall are more than those of the sample near the external wall. After the upper part of the hydrogen blisters were torn off, the fracture surfaces of the upper and lower parts of the blister were analyzed by scanning electronic microscopy (SEM) and energy dispersive spectroscopy (EDS). The cell segregation inclusion of alloying elements which contain Ca and Al sulfides and oxides were observed in most of the nucleation sites of hydrogen blisters. The result shows that the dislocations and the increasing vacancy concentration are the main reasons to form hydrogen cavities in the nucleation sites. The hydrogen pressure which exceeds the strength of the materials will cause the formation of hydrogen blister.
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