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1

The influence of micro-morphology and micro-structure on fly ash triboelectrostatic beneficiation

Wang Wenping, Chen Yinghua, Haisheng Li, Dong Haoran, Wang Guanghui

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 1

53--63

EN

Fly ash is a complex system with a variety of fine particles. The complex relationship between unburned carbon and ash particles has an important influence on the efficiency of fly ash triboelectrostatic beneficiation. The particles adhered to the two electrode plates are collected through the triboelectrostatic beneficiation experiment. The scanning electron microscopy and X-ray fluorescence are used to detect the microscopic differences between the particles of positive and negative plates. The results show that the flaky carbon particles in the raw ash and the ash particles larger than 4µm are more easily separated, while it is converse for the ash particles with particle size less than 4µm. With the particle size less than 4µm, it is gradually more obvious for the influence of adhesion caused by the roughness surface of spherical unburned carbon particles, and the surface pores structure of porous carbon particles. The binding structure between unburned carbon and ash particles is complex and changeable. It is not beneficial to improve the separation efficiency. Therefore, the micro-structure and micro-morphology have an important effect on fly ash triboelectrostatic beneficiation. Some suggestions were proposed from the microscopic point to improve the efficiency of fly ash triboelectrostatic beneficiation.

2

Formability of laser welded steel/magnesium dissimilar metal with Sn powder-adhesive interlayer

Tao Tao, Liu Jinshui, Zhou Dianwu, Yan Youruiling, Zhou He

Materials Science Poland

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2021

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Vol. 39, No. 1

113--123

EN

The exploratory experiments of laser fusion welding with Sn powder and the automotive adhesive addition were conducted for DP590 dual-phase steel and AZ31B magnesium alloy in an overlap steel-on-magnesium configuration. The characteristics of metal vapor/plasma were analyzed by collecting and analyzing plasma shape and welding spectra. The microstructure of the welded was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDS). The temperature field distribution of the joint was simulated by COMSOL finite-element software. The results showed that the transfer of heat from steel to the magnesium alloy is hindered by the adhesive layer, which is conducive to the simultaneous melting of steel and magnesium with large differences in melting and boiling points. In addition, the width of the molten pool increases, but the depth is shallow on the magnesium side. Meanwhile, the recoil pressure induced by the splashing of the molten pool reduces, and the surface quality of the weld is improved. Some intermetallic compounds (IMCs), such as FeSn, Fe1.3Sn, and Fe3Sn, are formed inside the molten pool, while columnar dendrite Mg2Sn phase is also produced. The presence of these phases helps realize the bidirectional metallurgical bonding of steel/magnesium dissimilar metals.

3

Microstructure optimization of alumina/zirconia materials resistant for abrasive wear

Pędzich Z., Wojteczko A.

Mechanik

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2016

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R. 89, nr 5-6

498--499

EN

Sintered particulate composites in corundum-tetragonal zirconia system are the group of materials often utilized as structural ceramics because of their relatively low cost and high level of mechanical properties. In the paper results of experiment correlating basic mechanical (strength, fracture toughness) and useful (abrasive wear resistance, subcritical crack growth) parameters with composites microstructure were presented.

PL

Spiekane kompozyty ziarniste w układzie korund-tetragonalne polikryształy dwutlenku cyrkonu są grupą materiałów często stosowaną jako ceramika konstrukcyjna, ze względu na stosunkowo niską cenę oraz dobry poziom właściwości mechanicznych. W pracy przed-stawiono wyniki eksperymentu korelującego podstawowe parametry mechaniczne (wytrzymałość, odporność na kruche pękanie) oraz użytkowe (odporność na zużycie ścierne, odporność na pękanie podkrytyczne) z mi-krostrukturą tworzyw kompozytowych.

4

A micromechanical approach to numerical modeling of yielding of open-cell porous structures under compressive loads

Hedayati R., Sadighi M.

Journal of Theoretical and Applied Mechanics

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2016

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Vol. 54 nr 3

769--781

EN

Today, interconnected open-cell porous structures made of titanium and its alloys are replacing the prevalent solid metals used in bone substitute implants. The advent of additive manufacturing techniques has enabled manufacturing of open-cell structures with arbitrary micro-structural geometry. In this paper, rhombic dodecahedron structures manufactured using SLM technique and tested by Amin Yavari et al. (2014) are investigated numerically using ANSYS and LS-DYNA finite element codes for the modeling of the elastic and postyielding behavior of the lattice structure, respectively. Implementing a micro-mechanical approach to the numerical modeling of the yielding behavior of open-cell porous materials is the main contribution of this work.One of the advantages of micro-mechanical modeling of an open-cell structure is that, in contrast to the macro-mechanical finite element modeling, it is not necessary to obtain several material constants for different foam material models through heavy experimental tests. The results of the study showed that considering the irregularity in defining the cross-sections of the struts decreases both the yielding stress and densification strain of the numerical structure to the values obtained from the experimental tests. Moreover, the stress-strain curve of the irregular structure was much smoother in two points of yielding and densification, which is also observable in experimental plots. Considering the irregularity in the structure also decreased the elastic modulus of the lattice structure by about 20-30%. The post-densification modulus was more influenced by irregularity as it was decreased by more than 50%. In summary, it was demonstrated that using beam elements with variable cross-sections for constructing open-cell biomaterials could result in numerical results sufficiently close to the experimental data.

5

Numerical analysis of consolidation settlement and creep deformation of artificial island revetment structure in a large-scale marine reclamation land project

Zhao J., Zhou T., Wang G.

Polish Maritime Research

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2015

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S 1

35--42

EN

In order to analyze the influential factors of soft foundation settlement in a marine reclamation land project, the consolidation settlement and pore pressure dissipation of the entire area are numerically simulated using Soft-SoilCreep Model, in which the PLAXIS finite element software for professional geotechnical engineering is applied and empirical data of Japanese Kansai’s airport project are used. Moreover, the figures of settlement and pore pressure results in the different basic period are drawn, and the corresponding analysis conclusions are obtained based on the comparison among the results from the computational parameters of depth. In addition,, the influence rules of various parameters on settlement results is concluded through running the parameter sensitivity analysis in Soft-Soil-Creep Model, and the experience and conclusions can be for reference in the design and con-struction of similar large-scale marine reclamation land project. Also the empirical value method of the creep index has not been applied widely. Further research needs to be done.