Papers by Author: Man Zhu

Abstract: The “Twelfth Five-Year” plan of China starts at the emission reduction task in controlling the total amount of ammonia nitrogen. Therefore, the method of how to remove ammonia nitrogen quickly and effectively will be the key point of wastewater treatment. In the current paper, One zeolite synthesized from coal fly ash (P-type zeolite, ZP) was prepared and then modified using lanthanum. The structure of the zeolite was characterized by means of SEM, X-ray, TG-DSC, and the like. The characteristics of ZP and lanthanum-modified ZP (LaZP) in the adsorption and desorption of ammonia nitrogen were simultaneously studied, wherein the results show that ZP and LaZP are featured with obvious crystal characteristics, lots of gap structures, and a strong characteristic peak of P-type zeolite shown in the XRD atlas. For the LaZP, the adsorption equilibrium can be carried out in 30 min. The data for the adsorption dynamics to the ammonia nitrogen are in line with the pseudo-second order kinetics equation, and the adsorption isotherme is well fitted to the Langmuir model. The regeneration test shows that the desorption rate of ammonia nitrogen is proportional to the concentration of NaCl when the pH is about 7. The desorption rate of LaZP to the ammonia nitrogen can reach 90% when the concentration of NaCl is 0.4 mol/l, and the desorption rate of ZP is 70%. Compared with ZP, the desorption speed of the LaZP is quicker, the adsorption equilibrium can be carried out in 6 h, and the adsorption equilibrium of ZP can be slowly carried out in 10 h. Moreover, the adsorption and desorption properties of the LaZP are greatly improved.

Abstract: By means of XRD, SEM, FE-SEM, and TEM, the microstructures and growth morphology features of icosahedral quasicrystal for rapidly solidified Mg-Al-Zn system were investigated. It was found that, single icosahedral quasicrystal can be obtained in the Mg-Al-Zn alloys. The icosahedral quasicrystal reveals three typical morphologies: well developed dendrites, coral-like, and petal-like, and its compositions are in a wide range composition with 42.87-48.89 at.%Mg, 13.78-17.03 at.%Al, and 34.22-40.60 at.%Zn. Pentagonal dodecahedron with icosahedral symmetries is seen, and certain steps in pentagonal faces suggest that the planar growth occurs on the pentagonal faces.

Abstract: In this paper, equilibrium phase diagram in Al-15Si-xCu system piston alloys was calculated using “Pandat” software. The influence of Cu content on the friction and wear behavior of Al-15Si piston alloys at elevated temperature was investigated by the combination use of optical microscopy (OM) and scanning electron microscopy (SEM). Experimental results showed that the abrasive and wear weight and the friction factor in the T6-treated piston alloys were reduced with the increase of Cu content. The friction and wear properties differ slightly in the piston alloys containing 4.5% and 5.5%Cu, which is related to the high thermally stable precipitates, i.e., Q-phase, ε-phase, and θ-phase. For the piston alloys containing low Cu content, the wear mechanism belongs to adhesive wear, while abrasive particle wear is responsible for the high Cu content piston alloys.

Abstract: The influence of T6 heat treatment on the microstructures and aging precipitation in the grain-refined A356 alloys were investigated. Experimental results showed that, when T6 heat treatment was performed, the average values of mean diameter, aspect ratio, and roundness of silicon particles in the grain-refined specimens were decreased to 2.26~3.14 μm, 2.06~2.2, and 3.1~4.2, respectively. DSC curves revealed that three kinds of precipitates, i.e., β″, β′, and β, were observed in both unrefined and grain-refined A356 alloys. The exothermic peaks in the grain-refined A356 alloy shifted to high temperatures, suggesting the nucleation of β″ precipitates was decelerated. This could be ascribed to the minor solution of Ti or B elements during solid solution treatment.

Abstract: ZnSe is a kind of important semiconductor photo-electricity materials, which has received common attentions. The preparation and photoelectric property of high quality ZnSe single crystal have become the focus on current research fields. In this paper, the preparation methods were discussed emphatically and optical and electrical properties were analyzed on these bases. Furthermore, the application prospective was discussed. Therefore, this paper provided research basis for preparation and application of ZnSe.