Advanced Materials Research Vols. 634-638

Abstract: The separation efficiency, separation factor, flow and other parameters are closely related in terms of horizontal spiral sedimentation centrifuge. This article takes lwb350 horizontal spiral sedimentation centrifuge for example, with the help of FLUENT software, the relationship among the separation efficiency and the working speed as well as feed flow is analyzed through the numerical simulation of solid-liquid separation, which can provide reference for the application of simulation analysis and research on properties of spiral centrifuge.

Abstract: A new single screw expansion machine was developed in order to improve the practical level of low temperature thermal power generation technology and the utilization of waste heat and renewable energy. With compressed air as working fluid, the power, efficiency, gas consumption rate and temperature difference of single screw expander with rotational speed variation had been studied in an established experimental apparatus of single screw expander . The results showed that, the maximum speed of expander reached 3393r/min, the maximum moment of torque reached 22N•m, the maximum power of expander was up to 4.4kW, and the maximum inlet flow rate was 32.9m3/h. The maximum temperature difference between import and export of expander reached 45°C. The lowest gas consumption rate was up to 55.2kg/kW•h, and the maximum total efficiency of expander reached 58.8%.

Abstract: This paper introduces the process of yellow phosphorus extraction from phosphorus sludge at moderate temperature and existing problems of the device. It is necessary to design the rotating seal joint of the device again. According to materials physical and chemical properties, the paper expounded materials choice of rotating seal joint parts.

Abstract: Thorough research is performed on crystallization process of ammonium persulfate，the influence of different mixing method on crystallization process of the ammonium persulfate is discussed in this paper, the influence of temperature on crystallization process is also discussed, and then the optimum mixing method for the crystallization of ammonium persulfate is achieved. All these will do great favor to improve the stability of crystallization process of ammonium persulfate .

Abstract: The plate heat exchanger in oil cooler of unit 2 in a thermal power plant became corrosion perforation after 2-year running, and severe pits were found on its surface. The material and scale composition of the lubricating oil cooler was analyzed, and it was found that the oil cooler was made of 304 stainless steel, instead of the 316 stainless steel provided by factory. The corrosion products on the corroded surface were composed of some characteristic elements in cooling water. The analysis suggested that the reason for corrosion perforation of the heat exchanger could be associated with its material composition, and the under scale corrosion formed under the action of scale deposition could also cause corrosion perforation and large-scale pits.

Abstract: The new experimental creep resistant ferritic steel of the 9Cr-3Co-3W type was oxidised at 650 °C in air and wet air. The oxidation kinetics was measured by intermittent weight measurement. The scales formed were analysed using techniques of XRD, SEM and EDS. The results showed that the oxidation rate was more than a magnitude faster in wet air than in air. The oxidation kinetics in air obeyed the parabolic rate law of oxidation only in a limited oxidation period of up to 1726 h whereas it did not follow any power rate law of oxidation in wet air. The steel cannot form a protective Cr2O3 scale either in air or in wet air at 650 °C. Instead, the scale formed in air consisted of an outer (Fe_0.6Cr_0.4)₂O₃ layer and an inner Cr-rich (Fe,Cr)₂O₃ layer containing Cr₂O₃ particles, but in wet air it consisted of an outer Fe₃O₄ layer and an inner (Fe,Cr)₃O₄ layer.

Abstract: In order to understand the effect of casting temperature on the low frequency electromagnetic casting process, 200mm billets of an Al-Zn-Mg-Cu alloy were produced, the microstructure was analyzed and the temperature field was measured during the casting process. The experimental results showed that low frequency electromagnetic casting process has an evident grain refining effect on aluminum alloy and casting temperature is not a sensitive parameter for this process, which can tolerate a large range of casting temperature. In the range of 710 to 750 °C, casting temperature does not show significant effect on the microstructure.

Abstract: Small amount of Ag was added to high conductivity Cu-5%Cr alloy in order to increase the strength without sacrificing the conductivity. The typical microstructure of thermo-mechanically processed specimen mainly consists of Cu matrix and relatively large Cr phase. Although this typical microstructure was not changed with varied process variables, both the micro-hardness and conductivity were significantly affected by them. The electrical conductivity of alloy was slightly decreased by the Ag addition, but the micro-hardness could be enhanced by it. TEM analyses indicated that very fine Cr precipitates were formed in addition to the relatively large Cr phase in the Cu matrix. It is suggested that the properties of Cu-5Cr-xAg alloys can be optimized by carefully controlling the precipitation of the fine precipitates.

Abstract: The corrosion process of rare earth (RE) SPCC steel and SPCC steel in CSP in 3.5% NaCl solutions was investigated by SEM, EDS, XRD and polarization curve measurements. The results show that grain refinement can be obtained, the inclusions will be formed, and the electrochemical corrosion of microscopic region is weakened and therefore the corrosion resistance of SPCC steel could be improved by addition of RE. The rust layer of RE treated steel generated in the solution is more compact, the α-FeOOH content in rust layer is higher, and the content of activated γ-FeOOH and β-FeOOH is smaller, which are helpful to protect the steel. It also shows that current densities of SPCC steel is lower and the corrosive tendency will decrease with the addition of RE, which also makes the corrosion resistance of steel improved.

Abstract: The austenite steel was radiated by the intermediate frequency pulsating magnetism, and the effects that pulsating magnetic on the austenite transition was studied. The result shows that the pulsating magnetism promotes the austenitic grain growth of low carbon steel. If the magnetic field intensity is increased, it could provide better performance of raw materials to cold rolling processing.