Advanced Materials Research Vols. 284-286

Abstract: This study investigates the effect of various injection molding process parameters and fiber amount on buckling properties of Polybutylene Terephthalate (PBT)/short glass fiber composite. The buckling specimens were prepared under injection molding process. These forming parameters about filling time, melt temperature and mold temperature that govern injection molding process are discussed. The buckling properties of neat PBT, 15 wt%, and 30 wt% are obtained using two ends fixed fixture and computerized closed-loop server-hydraulic material testing system. The fracture surfaces are observed by scanning electron microscopy (SEM). The global buckling forces are raised when increased the fiber weight percentage of PBT. Also, the fracture mechanisms in PBT and short glass fiber matrix are fiber pullout in skin area and fiber broken at core area. It is found that the addition of short glass fiber can significantly strengthen neat PBT.

Abstract: The surface modification of carbon nanotubes（CNTs）has been recently observed to influence the distribution of CNTs in epoxy resin and the mechanical properties and electrical conductivities of these CNTs. Accordingly, the treatment of CNTs to with organic acids to oxidize them generates functional groups on the surface of CNTs. This investigation studies the consequent enhancement of the mechanical properties and electrical conductivities of CNTs. The influence of adding various proportions of CNTs to the epoxy resin on the mechanical properties and electrical conductivities of the composites thus formed is investigated, and the strength of the material is tested at different temperatures. Moreover, the creep behavior of carbon fiber（CF）/epoxy resin thermosetting composites was tested analyzed at different stresses, orientations of fiber, temperatures and humidities. The creep exhibits only two stages- primary creep and steady-state creep. The effects of creep stress, creep time, and humidity on the creep of composites that contain various proportion of CNTs were investigated at various temperatures. However, increasing the number of cycles in cyclic creep tests at room temperature resulted in a decrease in creep strain even at a high temperature of 55°C. Possible room temperature creep mechanisms have been proposed and discussed. Creep strain is believed to increase with applied stress, creep time, humidity, temperature and degree of the angle θ between the orientation of fiber and the direction of the applied stress. The test results also indicate that mechanical strength and electrical conductivity increase with the amount of CNTs added to the composites. Different coefficients of expansion of the matrix, fiber and CNTs, are such that overexpansion of the matrix at high temperature results in cracking in it. An SEM image of the fracture surface reveals debonding and the pulling out of longitudinal fibers because of poor interfacial bonding between fiber and matrix, which reduce overall strength.

Abstract: In this paper, using a software, prepared by the General Research Institute for Nonferrous Metals to analyze rotation field in materials deformation. By using this software, we analyzed the deformation rotation field in process of tensile for CuY0.8 nano-alloy strip and Nickel-based alloy, and analyzed performed on the rotation behavior, rotation extent and its character among the grains after the polycrystalline metal materials had been yield-deformed, and getting rotation field which is coming with the CuY0.8 nano-alloy strip and nickel-based alloy deformed. It was observed that after plastic deformation, the nano-crystalline grains and its neighborhood occurred a rotation-induced change , the rotation blocks presented on pairs wise as gears, its rotation was in the opposite direction, and in the rotation-pairs region the energy transfer was observed. In the poly-crystalline nickel-based alloy, after plastic deformation among the crystal grains the rotation-pairs occurred in many locations. It is proposed that plastic deformation shows more intensively, the grains rotation angle will is bigger, and in the macroscopic point of view, the generation of Lüders bands is closely related with rotation between grain blocks.

Abstract: Nanocomposite based on polyaniline (PANI) and α-zirconium phosphate (α-ZrP) has been synthesized by in situ polymerization using aniline intercalation compound (ANI)/ZrP as intermediate. Aniline was successfully intercalated into the interlayer spacing of crystalline α-ZrP forming a double-phase intermediate by adsorption. The intercalated aniline was polymerized by adding appropriate amount of ammonium peroxodisulphate (APS) solution. The synthesized nanocomposites were characterized by XRD, SEM, and FT-IR. X-ray diffraction patterns showed that PANI was formed outside α-ZrP. TGA/DSC analysis showed improved thermal stability for the PANI/ZrP nanocomposite in comparison with pure PANI. The PANI/ZrP nanocomposite was studied by cyclic voltammetry (CV), which revealed good redox activity and electrochemical-cycling stability in acidic solution. The interaction between PANI and nanosheets greatly affected the electrochemical behavior of PANI/ZrP nanocomposite. The electrochemical behavior of PANI/ZrP nanocomposite in HCl solution with different pH values has been studied in detail.

Abstract: TiC particulates were prepared by self-propagating high temperature synthesis (SHS). The effect of elemental aluminum on the formation of TiC particulates was particularly studied by differential thermal analysis (DTA) and sintering experiments of Ti-C-Al system. The sintered products were examined by XRD and TEM. The results showed that Ti did not react with C directly in the absence of elemental Al. The sintering process of Ti-C-Al system presented typical high-temperature self-propagating synthesis (SHS) features. TiC particulates could be maximally obtained through the appropriate control of the Al content in the system. The size of the resultant TiC particulates was about 0.15μm.

Abstract: The electrochemical behaviors of zinc anode in the presence of the additives added to the electrodes are presented. LaCoO₃ was used as an additive to improve the electrochemical properties of the zinc anode. LaCoO₃ synthesized by sol gel method (Schiff base complex) was added to Zn and ZnO powder with the weight ratios of 1:0.05 and 1:0.002 respectively. The electrochemical properties of the zinc and zinc/LaCoO₃ electrodes in 6M KOH solution were investigated by voltammetric technique and electrochemical impedance spectroscopy (EIS). The cyclic voltammograms showed that zinc electrodes with LaCoO3 additive gave higher anodic currents and ZnO passivation delayed. The cathodic Tafel plot indicated that the hydrogen overpotential shifted toward more negative value. The EIS revealed that the charge transfer resistances of the zinc/LaCoO₃ electrodes were higher than that of zinc electrodes.

Abstract: The pipeline steels with excellent deformability becomes an important research direction of pipeline materials fields in recent years. In this study, the pipeline steels with excellent deformability was obtain by inter-critically accelerate cooling(ICAC) method, the influence of welding heat input on the microstructure and property of the coarse grain heat affect zone (CGHAZ) of X80 pipeline steels with excellent deformability is investigated using welding thermal simulation, mechanical testing and microstructure analysis. The result indicate that the strength and toughness of CGHAZ of X80 pipeline steels with excellent deformability decrease follow with welding heat input increase.

Abstract: Isotropic pyrocarbon was deposited on self-heating plate at 1100°C and atmospheric pressure via a novel deposition reactor. Two graphite papers were mounted horizontally in chemical vapor deposition furnace, which were used as self- heating plates with alternating current flowing through them. And the upper surface of the lower self-heating plate also was used as substrate of pyrocarbon deposition. The microstructure of the deposit was investigated by polarized light microscopy, scanning electron microscope, transmission electron microscopy and laser Raman spectra, respectively. The results showed that there were some irregular clusters of globular structure and onion-like structure in the deposits. The thickness and density of deposit were13-15 mm and 1.88 g/cm³ in 30h. A novel deposition model of electromagnetic effect on intermediate product has been developed in order to establish a better description of the deposition process.

Abstract: Nitrogen doped TiO₂/sepiolite composite materials (N-TiO₂/sep) with different nitrogen contents were prepared by a sol-gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), respectively. XRD and SEM results showed that anatase-TiO₂ nanoparticles were distributed homogenously on the surface of sepiolite. XPS revealed that N atoms could incorporate into the lattice of anatase TiO₂ substituting the oxygen atoms sites of oxygen atoms.

Abstract: Heterocyclic monomers based on 2,1,3-benzothiadiazole bearing solubilizing side chains have been synthesized in high yields over four steps from readily available starting materials. A multistep synthesis of the electron-poor 6, 7-dihydro-1, 4-dioxino-[2, 3-f][2,1,3]-benzothiadiazole are presented. The new dificient acceptor has good solubility in organic aolvents to permit an appropriate coating process.