The laponite (LAP) with intercalation of pesticide lambda-cyhalothrin (LCT) was prepared with surfactant of 3-sulphonyl hexadecyldimethylamine (SB) as accessory ingredient. The zwitterionic surfactant of SB, dodecyl dimethyl carboxylbetaine (DCB), N,N-dimethyldodecylamine N-oxide(OA) and cationic surfactant cetyl trimethyl ammonium bromide (CTAB) were separately intercalated into laponite (LAP), and then LCT was solubilized into SB micelles and intercalated into the galleries finally composites of LCT/SB-LAP, LCT/DCB-SB-LAP, LCT/OA-SB-LAP and LCT/CTAB-SB-LAP were obtained. These composites were systematically characterized by powder X-ray diffraction (XRD), liquid state nuclear magnetic resonance (1H NMR), inductively coupled plasma-optical emission spectroscopy (ICP-OES), fourier transform infrared (FT-IR) spectroscopy, thermogravimetry/differential thermal analysis (TGA/DTA) and scanning electron microscope (SEM). The results show that the interlamellar spacings of LCT/SB-LAP, LCT/DCB-SB-LAP, LCT/OA-SB-LAP and LCT/CTAB-SB-LAP were 3.61, 3.13, 3.13 and 3.41 nm, respectively. The LCT companying SB molecules entered into the interlamellar of LAP was confirmed by 1H NMR, ICP-OES and spectroscopy FT-IR. The intercalation mechanism of LCT induced by SB micelles was proposed. The release behavior of LCT from composites was investigated and analyzed. The release rates and cumulative amounts are mainly dependent on type and arrangement of surfactants in the interlamellar spacing.
The effect of Sc- and Zr-addition and annealing treatment on the microstructure and properties of as-cast Al-Si alloys were investigated by optical microscopy, transmission electron microscope, scanning electron microscope, microhardness and tensile test. The results show that the addition of Sc and Zr can significantly improve the mechanical properties of the Al-5.5Si alloy, as a consequence the hardness, tensile strength and yield strength of the alloy increased by 33%, 38% and 52% respectively, while the elongation kept basically unchanged. The addition of Sc and Zr in the Al-5.5Si alloy reduced the average grain size of α-Al from 203 μm to 130 μm, and a large amount of Al3 (Sc1-xZrx) nanoparticles (10~15 nm) precipitated in the α-Al matrix which can significantly increase the stacking faults or micro twinning density of eutectic Si. It is noted that the annealing temperature has a greater impact on the properties of the as-cast alloy: the hardness of the alloy had an increasing trend when annealing at lower temperature (below 160℃), and the hardness of the alloy had a decreasing trend when annealing at higher temperature (above 280℃). The significant downward trend can be attributed to the secondary precipitation of nano-Si phase.
The effect of pre-corrosion by salt spray on the extremely-low cycle fatigue performance of HRB400E steel was studied. The steel samples were firstly subjected to salt spray corrosion with NaCl solution for 30~90 days, and then subjected to extremely-low cycle fatigue test via an axial displacement control facility to simulate the strong earthquake loading. Therewith, the relationship between the loading and cycle numbers, as well as the strain-life curves were obtained. Finally, the fracture faces were characterized by scanning electron microscope (SEM). The results show that the decline rates of life after pre-corrosion for 30 days, 60 days and 90 days were 4.4%~10.2%, 14.3%~31.8% and 7.8%~30%, respectively. The crack initiation life accounts for 90% of the total life, and the strain amplitude of 3% is the turning point between ultra-low cycle and low cycle fatigue. Salt spray corrosion has no obvious effect on the cyclic response characteristics and Masing characteristics of the test material. At last, the fracture zone was crescent-shaped along the edge of the test material. Longer salt spray corrosion time and higher strain amplitude would lead to dimples in the final fracture zone.
The effect of B2O3 (B) and Al2O3 (Al) co-doping on electrical properties and microstructure of ZnO varistor ceramics are investigated. ZnO varistors doped with B and Al have excellent electrical properties such as low leakage current, high nonlinearity and low residual voltage. The electrical parameters of the ZnO varistor ceramics doped with 3.0% B and 0.015% Al(mole fraction)are as follows: breakdown voltage E1 mA=475 V/mm; leakage current JL=0.16 μA/cm2; nonlinear coefficient α=106; residual voltage ratio K=1.57.
NF/PDMA/MnO2-Co electrode was prepared by anodic electrodeposition on the foam nickel substrate, and which then was characterized by FESEM-EDS, XPS and Raman spectroscopy. The capacitance characteristics and Pb2+ adsorption behavior of the composite electrode were evaluated by cyclic voltammetry and capacitance adsorption desorption tests. The results show that the NF/PDMA/MnO2-Co composite electrode prepared by applied current density of 1 mA/cm2 at 30 ℃ for 3min has a higher adsorption capacity (59.9 mg/g) and specific capacitance (208.8 F/g) for the simulated wastewater of 20 mg/L Pb2+. The synergistic effect of the bottom layer of PDMA and the top layer of Co doped MnO2 can effectively improve the capacitance and adsorption performance of the MnO2 electrode. The adsorption kinetics fitting shows that the adsorption process is controlled by the mixture of physical and chemical adsorption, and is limited by the mass transfer of ions and the diffusion in pores. The stability of the electrode is higher, and its adsorption capacity is 51.7 mg/g after four cycles of adsorption.
The structural reliability of artificial mechanical heart valve made of pyrolytic carbon was assessed by means of damage tolerance methodology. In particular, a conservative estimation concerning the possible life-time, or the number of loading cycles was established, in that estimated duration, the pyrolytic carbon artificial heart valve can operate properly in service under given physiological loadings until a pre-existing flaw of minimum size grows gradually to the critical size. It is shown that a minimum pre-existing defect size computed is typically of the order of tens of microns for such pyrolytic carbon valve, for structural life of any pyrolytic carbon component in excess of patient lifetimes. The use of such analysis must be regarded as an essential requirement for the design and quality control of new and the existing pyrolytic carbon artificial heart valve in order to provide maximum assurance of patient safety.
Composites of Fe/Yb co-doped TiO2 hollow spheres (Fe/Yb-TiO2HS) were prepared by template method and then characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TG). The photocatalytic performance of the composites was assessed with a simulated wastewater of 20 mg/L methyl orange solution under radiation of visible light. The results show that the degradation efficiency of doped titanium dioxide hollow spheres for the methyl orange could be significantly improved. The composite doped with 0.1% Fe and 1% Yb presents the optimal photocatalytic performance with degradation efficiency up to 92.57% for the methyl orange.
The effect of deformation (deformation degree and deformation temperature) and annealing (annealing temperature and annealing time) on the microstructural evolution of Fe47Mn30Co10Cr10B3 high-entropy alloy were systematically investigated by electron backscattered diffraction and electron channeling contrast. The dominate deformation mechanism changes from dislocation slip to transformation-induced plasticity with the decreasing deformation temperature in case the strain is small. At room temperature, with the increasing strain the dominate deformation mechanism changes from dislocation slip to transformation-induced plasticity while second phase particles precipitate along the rolling direction. During recrystallization annealing treatment of the heavy deformed alloy, with the increasing annealing temperature the alloy presented the following microstructure evolution namely, changed from deformed microstructure (600℃-5 min) to partial recrystallization (800℃-5 min) and then complete recrystallization (1000℃-5 min). For the annealing at temperature (1000℃) with the increasing annealing time the microstructural evolution undergoes partial recrystallization (1 min) and complete recrystallization (5,15 min). In addition, the phase component transforms from single phase (γ) to dual phase (γ + ε). The annealing treatments do not change the distribution of second phase particles along the rolling direction. The high-entropy alloy shows a comprehensive mechanical performance with yield strength of 326 MPa, tensile strength of 801.9 MPa and elongation 26.8%, respectively.
Diamond-like carbon (DLC) thin films were deposited on silicon plates, placed at the top and bottom of the reaction chamber respectively, by plasma-enhanced chemical vapor deposition (RF-PECVD). Various DLC thin films were obtained by changing the flow ratio of CH4 and Ar(VCH4/VAr). The structure, surface roughness, surface morphology and hardness of DLC films were characterized by means of Raman spectroscopy and other methods. The results show that DLC films with different Ssp3/Ssp2 ratios could be prepared on bottom plates by changing VCH4/VAr, while the Ssp3/Ssp2 ratio kept constant for DLC films prepared on top plate. The films deposited on top plates placed near the gas inlet are smoother, denser, harder and more reproducible than that on bottom plates placed near the gas outlet.
