Key Engineering Materials Vols. 531-532

Abstract: Numerous stable complexes of boric acid with polyhydroxy compounds, including tartaric, salicylic, citric, malic, and other acids, are known. The structure of some compounds contains polyanion. In this paper, a novel potassium borate hydrate [K(H4B5O10) •2(H2O)] has been synthesized from a solution reaction and the crystal structure has been determined by means of single-crystal X-ray diffraction. Orthorhombic, Aba2. a = 11.0781(14) Å b = 11.1780(15) Å c = 9.0508(11) Å α=β=γ=90°. V= 1120.8(2) Å3. Z=4. Rgt = 0.0244, wRref = 0.0623. T= 298 K. The crystal packing is stabilized by O-H...O hydrogen bonds interaction and three dimensional framwork structure is formed. The work is originality and has a new crystallographic structure shape.

Abstract: Metal complexes containing diimine ligands such as 1,10-phenanthroline and bipyridine are very important and widely used in analytical chemistry, catalysis, electrochemistry, ring-opening metathesis polymerization and biochemistry. 1,10-phenanthroline, which is the parent for important class chelating agents, has been widely used in the construction of supramolecular architectures. Lots of phenanthroline and its derivatives complex have been synthesized and reported. In the paper, a novel Mn and 3,4,6,7-tetramethyl-1,10-phenanthroline complex [Mn(C16H16N2)2] •Cl2 has been synthesized from a solution reaction and the crystal structure has been determined by means of single-crystal X-ray diffraction. [Mn(C16H16N2)2] •Cl2, Orthorhombic, Pnna. a = 8.8376(8)Å b = 18.3630(17)Å c = 18.0159(18)Å α=β=γ=90°. V= 2923.7(5)Å3. Z=4. Rgt(F) = 0.0341, wRref(F2) = 0.0958. T= 273(2) K. The novel Mn metal complex structure is explained clearly.

Abstract: In the study of functional materials, more attention is the construction of organic–inorganic hybrid materials with structural diversity, fascinating properties, and potential applications in catalysis, molecular adsorption, medicine, electro-conductivity, magnetism and photochemistry. At present, the research work in upconversion emission in rare-earth doping materials has been greatly increased. Yb3+ and Ho3+ upconversion energy transfer is attractive, because Yb3+ and Ho3+ upconversion energy transfer is relatively simple compared to upconversion involving other rare-earth ions. In this paper, a novel holmium complex [Ho (C3 H6O9)] •CH3OH has been synthesized from a hydrothermal reaction and the crystal structure has been determined by means of single-crystal X-ray diffraction. The Ho atom is coordinated by eight O atoms. The molecular is antisymmetric structure by the C2-C2 axis. The molecular structure stabilized by the O-H…O hydrogen-bonding interactions.

Abstract: In engineering practice, the most widely used roof insulation materials are expanded perlite, expanded vermiculite, extruded polystyrene board (XPS), expanded polystyrene board (EPS), foam glass block，rigid polyurethane foam insulation layer, and so on. These products have many advantages, such as light weight, high compressive strength, good integral property, convenient construction. But there are a lot of defects at the same time, such as bad fireproof performance and durability, environmental pollution, and so on. So we need an efficient roofing insulation materials to meet the growing needs of the roofing energy saving, energy saving roofing insulation board system of polyphenylene foam concrete just meet this demand, it has the characteristics of thermal insulation, lightweight and compressive resistance, waterproof and moistureproof, fire durable, and simple structure. Through the application of this new materials in practical engineering, the energy saving roofing insulation board will provide an efficient and practical material for future roof thermal insulation and energy saving.

Abstract: Temperature of the polymer melt is one of the most important parameters for the polymer continuous extrusion molding process. There are many factors influence the distribution of the melt temperature, these factors have the coupling and nonlinear relationship which is difficult to measure accurately by the traditional measuring method. In this study, a BP neural networks-based model approach is presented in which the effects of the die wall temperature and screw speed and the wall temperature of the transition section and the measurement section in the continuous extrusion molding are investigated. Comparison of the BP neural networks model predictions with the experimental data yields very good agreement and demonstrates that the BP neural networks model can predict the polymer melt temperature field with a high degree of precision (the mean square error within 0.03)

Abstract: As a new type of composite structural system, the prestressed steel reinforced ultra-high strength concrete (PSRUHC) beam was applicable to large-span structures and those structures which must bearing heavy loading. But by now there is no mature calculation method for the beam with a good accuracy. So the experiment on eight post-tensioned bonded prestressed steel reinforced ultra-high strength concrete beams had been carried out to investigate the flexural performance of PSRUHC beams. Based on the test results, the flexural capacity of PSRUHC beams were analysed by the large general-purpose finite element program ANSYS. Compared the simulation results of cracking load, ultimate load, yielding load and load-displacement curve with the test results, it is proved that the numerical method is effective for analyzing flexural capacity of prestressed steel reinforced ultra-high strength concrete beams, which provides theoretical foundation for practical application of PSRUHC beam.

Abstract: Fe-Ni-Cr alloy powders with the different components were prepared by Mechanical Alloying (MA). The phase structure, grain size, micro-strain and lattice distortion were determined with X-ray diffraction. The morphology and particle size of the powders were observed and analyzed using a field emission scanning electron microscopy. The results showed that the Fe-Ni-Cr nanocrystalline powders could be obtained by MA. The ball milling time could be reduced with increasing amount of Cr, resulting the formation of Fe-Ni-Cr powders. With the increasing amount of Cr, the speed of Ni diffusion to Fe lattice approaching saturation became more rapid. The particle size got smaller as the ball milling went further; the extent of micro-strain and distortion of lattice intensified; the solid solubility of Ni and Cr in Fe was increased. Finally the super-saturated solid solution of Fe was obtained.

Abstract: The dispersion stabilities and thermal conductivities of Al2O3 and TiO2 ammonia water nanofluids are investigated by the absorbency index methods and transient double-hot-wire method, respectively. The results show that the dispersion stabilities of the two kinds of binary nanofluids are greatly improved by adding surfactants or increasing the ammonia content. The effective thermal conductivity ratios of the two kind of binary nanofluids increase with the increase of the content of nano-particles. It is the same with the increase of the ammonia content. The thermal conductivity will decrease with the rising of storage time by the role of natural sedimentation. The thermal conductivity of TiO2 nanofluid is more insensitive to the storage time than Al2O3 nanofluid because of its better dispersion stability

Abstract: Lithium tantalite (LiTaO3) thin film material shows good feasibility and potential for the application of high-performance detection system. In this paper, sol-gel process of LiTaO3 thin films on p-type (111) silicon substrates was described. Stable precursor solution with a desired viscosity was obtained using lithium acetate (LiAc) and tantalum ethoxide (Ta(OC2H5)5) as starting materials. Heat treatment process was optimized to fabricate LiTaO3 films of high crystallinity. Higher crystalline quality films were obtained when each spin-coating process was followed by an annealing operation. Microstructures and crystallization properties of LiTaO3 thin films were further studied. Nano-crystalline films were obtained after annealing at 700 °C for 5 min. The experimental results indicated that the crystallinity and mean grain size of LiTaO3 thin films were proportional to the film thickness.

Abstract: It is known that the high purity of carbon nanotubes (CNTs) are hard to obtain because of the impurities, which directly affect their unique properties and potential applications. Some modern purification methods including physical separation methods and chemical oxidation methods have been developed for getting the CNTs. But either way, each method still has some deficiencies, such as structure damaged, complex steps and low yield. Now there is a comprehensive multi-step method to overcome this predicament, it combines the air oxidation, hydrochloric acid treatment, SDS dispersion, centrifugation process, mixed acid oxidation and H2O2 oxidation. In this paper, the whole procedures of comprehensive methods are discussed in detail.