Advanced Materials Research Vol. 1088

Abstract: The fracture toughness and hardness of Ti (C_0.7N_0.3)-19Mo₂C-xNbC-24Ni cermets (x = 0, 5, 20) were studied. Fracture toughness of 5 NbC was the largest, and it of 20 NbC was the lowest. The microstructures of all the cermets consisted of Ti (C,N) and solid soluted Ti (C,N) hard phase, and Ni binder phase. The solid soluted Ti (C,N) surrounded Ti (C,N), namely, core-rim structures were observed in 0NbC and 5NbC. On the other hand, the isolated Ti (C,N) and solid soluted Ti (C,N) were observed in 20NbC, as a result of the phase separation between Ti (C,N) core and solid soluted Ti (C,N).

Abstract: High chromium cast iron and stainless steel bimetal were fabricated by liquid-solid composite casting .The interface diffusion behavior and microstructure evolution of high chromium cast iron were studied. The results indicated that interface element diffusion behavior between stainless steel and high chromium cast iron was obviously existed. Under experimental conditions, there were many refined grainy-shaped carbides precipitation in stainless steel near interface, located at austenite grain boundary and intragranular austenite. As for high chromium cast iron, the morphology of the carbides varied from the interface to the specimen edge. The rod shaped carbides approached to composite interface were finer and become coarser rod-like or blade-like with increased distance from the composite interface. The reasons for elements diffusion and microstructure change were associated with alloys contents and temperature field.

Abstract: Taking cup-shaped part (outer diameter D and wall thickness are chosen as 2.2 mm and 0.05 mm, respectively) as an example, the micro-back-extrusion forming process of a Zr₅₅Cu₃₀ Al₁₀Ni₅ bulk metallic glass (BMG) in its supercooled liquid region was studied by using finite-element analysis (FEM) and experiment. The effect of forming speed on the formability was analyzed based on the extrusion load, the rheological behavior of the material and the microstructure of the formed parts. It was found that while the forming speed is below than 4 μm/s, the extrusion load increases obviously with the increasing in forming speed, otherwise, the BMG will follow non-newtonian flow and the forming load is insensitive to the forming speed. The parts fabricated at 2 μm/s are obviously crystallized due to the long retention time of metallic glasses at high temperature, a higher forming speed is benefit to enhancing the formability if the BMG. On this basis, micro cup-shaped parts with only 0.05 mm in wall thickness are successfully extruded.

Abstract: Manganese lithium cobalt compounds have been used in the preparation of lithium battery cathode material because of its excellent electrochemical characteristics and gradually in recent years. This paper introduces the different methods of preparing the compounds, analyzes the structural characteristics of the manganese cobalt lithium compounds and the differences in the electrochemical properties, the end of the article has carried on the forecast to the future development direction of the compound.

Abstract: A novel substance, bi-(2, 4-dihydro-2H-3-(4-N-maleimido) phenyl-1, 3-benzoxazine) isopropane (BMIPBI), was investigated by density functional theory and calculation at the B3LYP/6-311+G* level for its molecular geometric configuration, infrared spectrum, electronic absorption spectrum and thermodynamic properties. The results demonstrated that, in the stable configuration of a BMIPBI molecule, the two side chains of 2, 4-dihydro-2H-3-(4-N-maleimido) phenyl-1, 3-benzoxazine connecting with both ends of the isopropane were not in the same plane, and the two side chains were rather different in structure. The minimal energy jump of gaseous molecules located at 533 nm, corresponding to π→π* jump of HOMO→LUMO. Along with the increase of the solvent’s polarity, the minimal energy absorption wavelength shifted to blue, mainly originated from changes in the transition properties, corresponding to π→π* jump of HOMO→LUMO+1. At 298.15 K and standard atmospheric pressure, the standard molar formation enthalpy and standard molar formation free energy of formation of the TMIPT molecule was-1212.46 and-532. 94 kJ/mol, respectively.

Abstract: "Click chemistry" was used in this paper to get a novel hyaluronic acid (HA) hydrogel by modified HA molecules' side chains with azide and alkynyl groups to perform "Click" reaction. The HA hydrogel can be achieved "in situ" injection gel. The properties of the HA hydrogel can be controlled by controlling the amount of alkynyl and azide groups on side chains to achieve controllable HA hydrogel by HA molecular design. The reactant, product and hydrogel were characterized by ¹H NMR, FTIR and morphology observation to determine the processes of reaction and can hydrogel formation.

Abstract: Synthesis and characterization of a novel hexabenzocoronene (HBC) derivative attached with four alkyl swallow-tailed chains and two sulfur-containing chains are described. The designed peripheral decoration with dove tails as solubilizer and sulfur-containing groups as functionalizer is expected to improve the solubility of molecules, change the columnar spacing stacks and make for its orientation on matrix surface. Its UV−vis absorption spectra appeared in 350-400 nm region as same as typical that of this kind of compounds. The thermal properties as discotic liquid crystal and its orientation on matrix are being studied.

Abstract: The spindle or spherical cobalt oxalate powders were prepared by conventional precipitation in the presence of pulsed electromagnetic field (PEMF). The morphology and phase structure were characterized by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). The aspect ratio and surface fractal dimension of cobalt oxalate aggregate were calculated using Image tool software and Differential Box Counting (DBC) algorithm. The results indicate that the products prepared from ammonium oxalate and cobalt chloride give rise to the formation of β-CoC₂O₄∙2H₂O. With the increase of pulsed time, the morphology of cobalt oxalate sample varies periodically from rod-like to spheroidic. For the sample treated for 60 s, the degree of sphericity is the highest. The surface fractal dimension is 2.096 and the corresponding fractal form is tight type.

Abstract: Spherical and fine cobalt powders were prepared by thermal decomposition of cobalt oxalate precipitated in the presence of pulsed electromagnetic field (PEMF). The morphology and phase structure were characterized by scanning electron microscopy (SEM), atomic force microscope (AFM) and X-ray powder diffraction (XRD). The aspect ratio was calculated by image tool software and the average size of cobalt particles was measured by laser particle size analyzer. The results indicate that both products prepared from cobalt oxalate with or without PEMF give rise to the formation of β-Co. The morphology of both products is similar to that of the precursors. The presence of PEMF plays an important role in formation of spherical and fine cobalt particles.

Abstract: The construction, crystal structure and properties and potential application of metal imidazoledicarboxylate frameworks have currently attracted considerable attention. A novel open-framework Lanthanide imidazoledicarboxylate, [Tb (HpyimdC)(C₂O₄)_0.5(H₂O)]·(H₂O)₃ (compound 1), was constructed from 2-(pyridine-3-yl)-1H-4,5-imidazoledicarboxylate (H₃PyImdc) and Oxalate coordinated with lanthanide under solvothermal conditions. Single-crystal X-ray diffraction analysis reveals that compound 1 crystallized in the monoclinic space group C2/c (No. 15). Oxalate chelated with Tb to form a one-dimensional zigzag chain, H₃pyimdc with selective nitrogen−oxygen chelating site, constructed these chains into metal organic frameworks featuring extra-large channels deposited by guest molecules. Further characterizations for compound 1 have been performed, including X-ray powder diffraction, IR Spectrum and elemental analysis. Synthesis, crystal structure and structural characterizations for 1 were reported in this paper.