Advanced Materials Research Vols. 239-242

Abstract: The excellent properties of Mg-Li alloys make them suitable light fabrication materials used extensively in many applications. The microstructure and the surface oxide film at different temperature of as-cast Mg-7Li alloy were investigated by optical microscope(OM), scanning electron microscopy(SEM), X-ray diffraction(XRD) and electronic analytical balance. Results showed that Mg-7Li alloy was composed of mainly α phase and β phase. With increasing temperature, the morphology of the alloy surface varied from the formation of a very thin oxide film, large amounts of oxide particles to the thick and coarse film with a mass of cellular protuberances in size of 40-80μm. The ratio of oxidation weight gains rose from 0.08% to 11.58%. The surface oxide film consisted of mainly magnesium oxide(MgO) phase and lithium peroxide(Li₂O₂) phase, resulting from the reaction of oxygen with Mg and Li. The volume of the oxides on β phase greater than that on α phase led to the formation of cellular protuberance on the surface of Mg-7Li alloy at high temperature.

Abstract: A high yield of ultralong SnO₂ nanowires is successfully achieved by a simple thermal evaporation of SnO powders under air ambient. The as-synthesized SnO₂ nanobelts are single crystals with rutile structure. A backgated triode device for high-current applications has been developed with beltlike SnO₂ field emitters. The devices have confirmed triode operation with low turn-on gate voltage (about 170 V) and stable electron emission with brightness of 30 cd/m².

Abstract: By means of optical microscopy(OM), scanning electron microscopy(SEM),X-ray diffraction(XRD),And tensile test, Mechanical Properties of hot rolled transformation -induced plasticity (TRIP) steels which were prepared through three different coiling temperature was investigated. Result reveals that the formability index of the experimental steel descends when the coiling temperature becomes low. Different coiling temperature has greater impact on retained austenite. Amount and carbon content of retained austenite in the experimental steel get less with lower coiling temperature.

Abstract: Transparent phosphosilicate glass-ceramics were prepared by heating the spontaneously crystallized precursor glasses in which crystals have formed during cooling of the melts. And the effects of compositional variation on the crystalline phases, degree of crystallization and transparency were investigated by using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). It is found that Mg²⁺ tends to exist in silicate-rich phase rather than phosphate-rich phase, such MgO is more beneficial to the transparency of phosphosilicate glass-ceremics compared to CaO. In addition, the substitution of P₂O₅ for SiO₂ enhances the tendency of phase separation, and hence the precipitation of Na₂MgSiO₄ crystals for the precursor glasses as well as glass-ceramics with good transparency.

Abstract: Using stearic acid-lauric acid binary of fatty acid as phase change material, waste polyacrylonitrile fiber (PAN) as supporting material, organic montmorillonite (OMMT) as modifier, and N, N-dimethylformamide as solvent, OMMT-PAN-binary fatty acid composite phase change materials(PCM) is prepared by solution blending. Using Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TG) study the structure and properties of PCM, the optimized preparation techniques of PCM obtained by orthogonal tests. SEM results showed that the PCM was homogeneous structure, binary of fatty acid dispersed in the continuous phase PAN; TGA results indicated that the degradation of the phase change material can be divided into three steps; DSC results showed that the crystallization enthalpy of PCM reached 143.27 J/g, the phase change temperature was around 23°C, and the DSC thermal circulation showed good thermal stability of the PCM; cooling curve showed that the PCM had good heat insulation properties, holding time reached 800s, and after repeated thermal circulation, heat insulation properties remained the same.

Abstract: A new Hg²⁺-sensing and selective fluorescent sensor, 1-(1-pyrenecarboxaldehyd e)-thiocarbohydrazone, was synthesized and characterized by elemental analysis, FT-IR and ¹H NMR spectra. Its fluorescence and recognition properties to the mercury ion were studied by the fluorescence emission spectra. With adding mercury ion into solution, the fluorescence emission intensities at different characteristic wavelength changed continually. Hence the ratiometric fluorescence measurement was used for detecting the complex process. It was found that a 1:1 stoichiometry complex is formed between the mercury ion and the compound with the association constants were 2.04×10⁵ L/mol, respectively. And the detection limits of the mercury ion were 2.52×10^-8 mol/L.

Abstract: This paper researched the fabrication of perovskite (CaTiO₃) synroc by combustion synthesis (CS) and the characterization of the products. This synthesis process is simpler, the fabricated synroc can immobilize waste loading up to wt( 36%) SrO with satisfied physical properties (density>4.2 g•cm^-3, open porosity<0.2%). The microstructure analyses by XRD and SEM/TEM show that the major phase is perovskite which well agrees with the design. It proves that CS offer a suitable Sr-waste into perovskite (CaTiO₃) synroc which is favorable for geological disposal.

Abstract: The fly ash has become a major industrial solid waste of emissions in China. Lots of fly ash will not only take the land directly but also pollutes the atmospheric environment seriously. As a mineral admixture, fly ash concrete can not only improve technical performance of concrete, but also make full use of the industrial waste. Moreover, it is significant to reduce energy, resource consumption and environment contamination. Experiments show that the performance of high volume fly-ash concrete is good for the need of pavement engineering. It has important social significance to apply high volume fly-ash concrete in mining roads.

Abstract: In this paper, nesquehonite whiskers were synthesized by low-temperature aqueous solution method, and the impacts of reaction temperature, reaction time and surfactant dosage and other factors on the maximum whisker length and high aspect ratios of nesquehonite whiskers were also investigated. Results showed that under the conditions that the reaction temperature was 40 – 50 °C the reaction time was 50 – 60min and the amount of surfactant dosage was 1% (by mass), high aspect ratios nesquehonite whisker products can be synthesized. On this basis, growth mechanism of the nesquehonite whiskers was discussed.

Abstract: Catalytic ozonation of p-Chloronitrobenzene (pCNB) in aqueous solution has been carried out where pumice have been used as the catalysts. The presences of the catalysts significantly improve the degradation efficiency of pCNB and the utilization efficiency of ozone. The adsorption of pCNB is too small to make a significant contribution to the degradation of pCNB in either of the processes of catalytic ozonation by pumice. Addition of t-BuOH causes the obvious decrease of degradation efficiency, suggesting that degradation of pCNB follows the mechanism of hydroxyl radical (OH) oxidation. Some of the main operating variables like dosage of catalyst and reaction temperature exert a positive influence on the degradation efficiency of pCNB.