Applied Mechanics and Materials Vols. 423-426

Abstract: As metal oxide semiconductor, tungsten oxide is studied and applied extensively because of its electrochromic property, gasochromic property, photochromic property, and gas sensing property. In this paper, the doped and undoped WO₃ were prepared by the precipitation method and the molten salt method. The crystals were characterized by FT-IR spectrometer and fluorescence spectrometer. The fluorescence spectra showed that the doping lanthanum and strontium can effectively improve the luminescence properties of the product. IR spectra indicated that the products contain WO₃ and H₂O. The photocatalytical degradation of methyl orange under UV light irradiation using WO₃ was investigated, which shows that the iron-doping can effectively improve the WO₃ photocatalytic degradation activity.

Abstract: Fe₃O₄ magnetic nanoscale water-based magnetic fluid was fabricated by co-precipitation with citric acid (CA) and polyethylene amine (PEI) as dispersant. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM) were used to investigate the samples.The modified magenetic nanoparticles (MNPs) size of about 50nm and have a saturation magnetization about 0.25emu/g.These nanoparticles can be applied to the study of genophore.

Abstract: The bismuth nanoparticles are synthesized via a solvothermal reduction method based on the chemical reduction of Bi³⁺ by ethylene glycol acting as the solvent and the reducing agent. The structural and morphological properties of the bismuth nanoparticles are investigated by X-ray diffraction and scanning electron microscope. The results demonstrate that the synthesized powders has a rhombohedral crystalline structure and their diameters are in the range of 75-103 nm under the condition of the different initial bismuth nitrate concentrations with the reduction temperature of 200°C, indicating that the thermal reduction temperature and the initial bismuth nitrate concentrations are key factors for phase composition as well as crystal size.

Abstract: Poly (methyl methacrylate) (PMMA)-graft-cellulose nanofibers (CeNFs) (PMMA-g-CeNF) were synthesized by means of graft-polymerization using Azo initiator in aqueous medium. The synthesized grafted fibers were characterized by Fourier transform infrared spectroscopy (FT-IR). Then, PMMA-g-CeNF were hydrolyzed by acid hydrolysis method with different acid constant and hydrolysis time and characterized by gel permeation chromatography (GPC). Finally, PMMA-g-CeNF was characterized by thermo-gravimetric and differential thermal analyses (TG-DTA).

Abstract: Bi₂WO₆ doped with iodine ions were synthesized using hydrothermal method and their photocatalytic activities to degrade Rhodamine B (RhB) under visible-light was investigated. The successful incorporation of I ions in Bi₂WO₆ was proved by XRD and XPS. UV-vis absorption spectra results show that I ion was successfully doped into Bi₂WO₆ and a red shift for I-doped Bi₂WO₆ appeared when compared to pure Bi₂WO₆. The photocatalytic activities of the photocatalysts were evaluated by the decolorization of RhB under visible-light irradiation. The results showed that the photocatalytic activity of I-doped Bi₂WO₆ was much higher than the undoped Bi₂WO₆.

Abstract: The zinc-rich coating prevents steel from corrosion by sacrificing electrochemical cathode anode protection, but the zinc content is the most important parameter. In this paper, the zinc-rich coatings made with the amino resin, acrylic resin, complex solvents, auxiliary agents and high purity zinc powder. The coatings were applied onto steel substrate and then placed in neutral salt spray for 3000 h in order to study the anti-corrosion performance. The results showed that the anti-corrosion performance was promoted with the zinc content increasing. When the zinc content was higher than 86 wt. %, the anti-corrosion performance can be reached 3000 h. The anticorrosion mechanisms were studied by polarization curves and scanning electron microscope (SEM).

Abstract: The hot-dip coatings containing Zn-Al-Mg-Ce were prepared through congruent melting. The anti-corrosion performance of the coatings was researched using the weight loss rate by the neutral salt spray testing. The reasons of the effects of the elements Al, Mg, Ce on the anti-corrosion performance promoting were researched through the analysis of Scanning Electron Microscope and the polarization curves. The results showed that Al, Mg, Ce embedded in the Zn matrix uniformly and the protective effect for the steel was enhanced by the electrochemical action.

Abstract: This paper illutrates the role of aging precipitates and the effects of nitrogen content on mechanical properties of 18Cr-18Mn-2Mo-0.77N (HNS-77), 18Cr-18Mn-2Mo-0.96N (HNS-B) and 18Cr-16Mn-2Mo-1.1N (HNS-110) through Vickers hardness, Charpy impact (CVN) and uniform tensile methods. The results show that intergranular, cellular Cr₂N and χ phase precipitate gradually in three HNSs aged at the nose temperature for different time. Based on transmission electron microscopy (TEM) analysis, intergranular and cellular Cr₂N precipitation has a hexagonal structure and intermetallic χ phase has a B.C.C structure. Compared to the solution treated specimens, Vickers hardness of HNS-77, HNS-96 and HNS-110 aged at nose temperature with increasing the aging time firstly decreases then increases; impact absorbed energy, ultimate tensile strength (UTS) and elongation (El) decrease monotonously. Yield strength (YS) of HNS-77 and HNS-96 firstly increases then decreases except HNS-110 with a monotonously decreased trendency. Vickers hardness of HNS-77, HNS-96 and HNS-110 arrives at the maximum value at nose temperature. Meanwhile, impact absorbed energy arrives at the minimum value. Impact absorbed energy of aged HNSs decreases with the formation and increment of intergranular, cellular Cr₂N and intermetallic χ phases. With increasing the nitrogen content, aging behavior of HNS presents more obvious susceptibility. The rate of increased amount and size of intergranular, cellular Cr₂N and relative minor χ phase grows and affects the mechanical properties of aged HNS remarkably.

Abstract: Transformation induced plasticity steels (TRIP steel) is a kind of low – alloying high strength steel with good combination of strength and plasticity. But the macro mechanical properties depend on the microstructure greatly. For simulation, macro finite element can’t consider the microstructure development fully and micro molecular dynamics can’t be used in macro engineering widely, so to investigate the material behavior of trip steel a multi-scale simulation framework which combined macro finite element simulation and micro molecular dynamics together was presented in this paper. The transformation technology between macro and micro simulation by internal variable was considered and macro displacement of integral point as boundary condition of micro molecular dynamics was discussed.

Abstract: According to thermodynamics of materials, selection of microalloying composition for developing cold rolled structural steel sheet with different strength levels was investigated, by comparing and analyzing the solid solubility and lattice constant of microalloying elements V, Nb and Ti, ideal microalloying composition-niobium and titanium compound additives was obtained, and then process parameters including reheating temperature and annealing process were discussed.