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The isothermal section of the Co-Mo-Zr ternary system at 1000 °C was investigated by using 29 alloys. The annealed alloys were examined by means of x-ray diffraction, optical microscopy, and electron probe microanalysis. It was confirmed that three ternary phases, λ1 (Co0.5-1.5Mo1.5-0.5Zr, hP12-MgZn2), ω (CoMoZr4) and κ (CoMo4Zr9, hP28-Hf9Mo4B), exist in the Co-Mo-Zr ternary system at 1000 °C. And the experimental results also indicated that there are sixteen three-phase regions at 1000 °C. Thirteen of them were well determined in the present work: (1) (γCo) + Co11Zr2 + Co23Zr6, (2) (γCo) + Co23Zr6 + ε-Co3Mo, (3) Co23Zr6 + ε-Co3Mo + μ-Co7Mo6, (4) (Mo) + μ-Co7Mo6 + Co2Zr, (5) (Mo) + Co2Zr + λ1, (6) (Mo) + Mo2Zr + λ1, (7) λ1 + Mo2Zr + CoZr, (8) Co2Zr + CoZr + λ1, (9) Mo2Zr + CoZr2 + ω, (10) κ + Mo2Zr + ω, (11) CoZr2 + liquid + ω, (12) (βZr) + liquid + ω and (13) (βZr) + κ + ω. The homogeneity of λ1 spans in the range of 28.66-50.77 at.% Co and 15.71-37.03 at.% Mo, and that for ω is within the range of 18.66-23.64 at.% Co and 8.53-14.68 at.% Mo. The homogeneity range for κ is from 8.09 at.% to 9.94 at.% Co and 23.13 at.% to 25.58 at.% Mo. The maximum solubility of Zr in μ-Co7Mo6 phase, Mo in Co2Zr phase and Co in Mo2Zr phase were determined to be 6.17, 11.27 and 9.14 at.%, respectively. While the solubility of Zr in ε-Co3Mo and (γCo) phases, Mo in Co11Zr2 and CoZr phases were detected to be extremely small. According to this work, the Co23Zr6 phase contained 15.61 at.% Mo and 12.7 at.% Zr. In addition, the maximum solubility of Co and Zr in (Mo) phase and Mo in (γCo) phase were measured to be 3.50, 5.44 and 7.40 at.%, respectively. [ABSTRACT FROM AUTHOR]

The ac-based electrical capacitance tomography (ECT) system has been successfully used for visualizing gas–solid flow in various industrial processes, such as pneumatic conveyor and fluidized bed. However, the solid particles in gas–solid systems are charged due to the collisions between particles and pipe wall. The particle charging decreases the image reconstruction accuracy of the ac-based ECT system and even leads to the reconstruction image distortion. In this paper, the electrostatic effect on ECT by particle charging is first investigated theoretically, and then experiments on a belt conveyor rig are performed to verify the electrostatic effect. Experimental results showed that the particle charging causes the additional output of the ac-based C/V conversion circuit. When the additional output makes the output of the circuit in its saturation region, the reconstruction image from the ac-based ECT system is completely distorted. However, the particle charging has no effect on the ac-based ECT system when the output signal of the C/V conversion circuit is within its allowable output range. By choosing a suitable amplifier and appropriate feedback resistance and capacitance values ( R\!f and C\!f ), the saturation of the output signal of the $C/V$ conversion circuit is avoided, and so, the electrostatic signal superimposed on the output capacitance signal of the $C/V$ circuit can be completely removed by a bandpass filter due to their distinct frequency characteristics. As a consequence, the electrostatic effect on the ac-based ECT system can be eliminated by optimizing ac-based $C/V$ conversion circuit. [ABSTRACT FROM PUBLISHER]

Low Pt-loaded graphene nanocomposites were prepared using a two-step reduction process. Graphene dispersion was first prepared from graphene oxide using hydrazine hydrate as a reducing agent. Pt-reduced graphene oxide composites were then synthesized in the aqueous graphene dispersion at 90 °C without the need for another reductant. Pt/graphene composite films were then deposited on fluorine-doped tin oxide substrates using a simple drop-casting method at room temperature and subsequently used as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). Cyclic voltammetry and electrical impedance analysis show that the composite electrodes have high electrocatalytic activity toward iodide/triiodide reduction. The energy conversion efficiency of the Pt/graphene CE-based DSSC was found to be 1.9 % lower than that of cells with a Pt-based CE. [ABSTRACT FROM AUTHOR]

Preparation of graphene composite material suitable for drop-coating on FTO conductive glasses in ambient conditions is reported. Highly dispersed PEDOT:PSS/graphene composites were synthesized by in situ polymerization of 3,4-ethylenedioxythiophene (EDOT) using aqueous graphene dispersions as a precursor without the need for further reducing steps. The structural properties of the PEDOT:PSS/graphene were investigated by transmission electron microscope and FT-IR spectrometry. Graphene sheets as the support material likely provided increased active sites for the polymerization of EDOT. The graphene sheets were homogeneously coated by PEDOT:PSS. Drop-coating the solution of PEDOT:PSS/graphene nanocomposites onto FTO glass yielded graphene composite counter electrodes (CEs) useful for dye-sensitized solar cells (DSSCs). Both in cyclic voltammetry measurements and electrochemical impedance spectroscopy, the composite CEs exhibited good catalytic activity. The DSSCs based on PEDOT:PSS/graphene CEs showed a conversion efficiency of 4.66 %, comparable to platinum CE-based cells which showed a conversion efficiency of 5.94 %. [ABSTRACT FROM AUTHOR]

The signal quality and accuracy of the spatial filtering method for solid particle velocity measurement based on a linear electrostatic sensor array (LESA) are dependent on the spatial filtering characteristics of the LESA and particle distribution in a pneumatic conveying pipeline. In this paper, the charge induced on a circular LESA with different geometric sizes from a single particle having a unity charge is mathematically modeled. Furthermore, a dimensionless computation model of the sensitivity of the LESA is suggested based on a fitted cosine function to the finite-element calculation results of the mathematical model, and the spatial filtering characteristics and spatial selectivity of the LESA are quantitatively investigated based on the computation model. Experimental work was performed on a purpose-built particle flow test rig to verify the dimensionless computation model and the modeling results. Results obtained reveal that the LESA acts as a narrow-bandpass filter in the temporal and spatial frequency domains, and its spatial selectivity is closely related to the number, spacing, and width of the electrode. These results provide an important basis for the performance improvement and optimized design of the LESA for particle velocity measurement. [ABSTRACT FROM PUBLISHER]

Abstract: The spatial sensitivity, spatial filtering effect, temporal frequency response characteristics and bandwidth are important parameters influencing the accuracy and response speed of a ring-shaped electrostatic inductive sensor. In this paper, the charge induced on the ring-shaped sensor with different geometric sizes from a single particle having a unity charge was modeled mathematically. And from the numerical solution obtained using the finite element analysis software ANSYS, the spatial sensitivity of the sensor was derived. The effect of the geometric size of the sensor on the spatial sensitivity was also investigated, and its spatial filtering fundamental theory and spatial filtering effect were also analyzed quantitatively. The temporal frequency response characteristics of the sensor were also derived. The experimental results on a gravity-fed conveyor were presented. The theoretical and experimental results obtained demonstrate that the ring-shaped sensor acts as a low-pass filter in the spatial frequency domain and its spatial frequency characteristics are closely related to the radial position of the charged particle and the axial length of the electrode. The measurement system, including the probe and signal conditioning circuit, acts as a band-pass filter, and the radial position, the axial length of the electrode, particle velocity and particle size have important effects on the temporal frequency characteristics of the measurement system. [Copyright &y& Elsevier]

In this study, one- and two-step chemical reduction methods were compared in terms of the production of Pt/graphene nanocomposites with low platinum (Pt)-loadings. Cyclic voltammetry and electrical impedance analysis indicated that the composites displayed high electrocatalytic activity with respect to the reduction of iodide/triiodide. Furthermore, the Pt/RGO composites were deposited on fluorine-doped tin oxide substrates by drop coating and were applied as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The energy conversion efficiency of the DSSCs based on Pt/RGO CEs (prepared using the one-step reduction method) was only 0.9% lower than that of the Pt CE-based cell. [ABSTRACT FROM AUTHOR]

Abstract: Water-soluble polyaniline/graphene nanocomposites have been prepared via a simple in situ polymerization of aniline in graphene dispersion. TEM measurement confirmed that polyaniline was homogeneously coated on the graphene sheets. The nanocomposites solution can be used for film fabrication by common technology, such as drop coating. When these different polyaniline/graphene nanocomposites were applied as the counter electrode materials for dye-sensitized solar cells, the short-circuit current density and power-conversion efficiency of the devices were measured to be 12.19mAcm−2 and 4.46%, respectively, which was comparable to 5.71% for the cell with a Pt counter electrode under the same experimental conditions. [Copyright &y& Elsevier]

Highlights: [•] TiO2 film electrodes have been successfully sensitized with CdS QDs. [•] DSSC based on CdS QDs-sensitized TiO2 film with 4min has the highest efficiency. [•] CdS QDs can improve the electron transport and reduce the electron recombination. [•] Our work open up a new avenue for the development of DSSCs. [ABSTRACT FROM AUTHOR]

Abstract: A TiO2 double-layer composite film consisting of hierarchically sponge-like macro-/mesoporous TiO2 (HSMM–TiO2) as overlayer and commercial-grade TiO2 nanoparticles (P25) as underlayer is designed as the photoelectrode of dye-sensitized solar cells (DSSCs). The photoelectric conversion performances of DSSCs based on P25 nanoparticle film, HSMM–TiO2 film, and P25/HSMM–TiO2 double-layer composite film are investigated and compared. It is found that the overall energy-conversion efficiency of 5.48% is achieved by the formation of P25/HSMM–TiO2 double-layer composite film, which is 51.4% higher than that formed by P25 nanoparticle film (η =3.62%) and 27.1% higher than that formed by HSMM–TiO2 film (η =4.31%) under identical film thickness (ca. 20μm) at a constant irradiation of 100mWcm−2. The enhanced conversion efficiency of TiO2 double-layer composite film can be attributed to the combined effect of the following factors. The HSMM–TiO2 overlayer enhances light-harvesting efficiency due to its intense light scattering and the P25 nanoparticle underlayer ensures good electronic contact between TiO2 film and the F-doped tin oxide (FTO) glass. Furthermore, the high specific surface area and special pore-wall structure of HSMM–TiO2 are respectively beneficial to adsorption of dye molecules and transport of both electrons and electrolytes. [Copyright &y& Elsevier]

In this paper, an instrumentation system for the measurements of local solid volumetric concentration, local solid velocity, local solid mass flowrate and solid mass flowrate in gas-solid two-phase flow system is developed. It is based on a new type of a Capacitance-Electrostatic sensor (CES). The CES sensor is mainly composed of a capacitance electrode array and two electrostatic electrode arrays. The optimum design of the sensor is achieved by finite element method. The capacitance electrode array is employed to detect the solid distribution over the cross-section of the pipe, and the local solid volumetric concentration measurement is further derived. The electrostatic electrode arrays are used to measure the local solid velocities in conjunction with cross-correlation method. From the local solid velocity and local volumetric concentration, the solid mass flowrate and the local solid mass flowrate can be achieved. The developed system for the local solid volumetric concentration measurement is verified through analogue simulation experiments and static experiments. Finally, the system is employed to measure the local solid volumetric concentration, local solid velocity, local solid mass flowrate and solid mass flowrate on a belt conveyor. The experimental results show that the measurement error of the local solid volumetric concentration measurement results are less than 10.43% for solid local volumetric concentration ranging from 0.02 to 0.56, the standard deviations of the local solid velocity measurement results are less than 0.42 for solid velocity ranging from 3.5 m/s to 15.0 m/s, and the relative error of the solid mass flowrate is within −19.6% to +14.9% for solid mass flowrate ranging from 0.006 kg/s to 0.103 kg/s, indicating that the system is capable of achieving multi-parameters measurement in gas-solid two-phase flow system. [ABSTRACT FROM AUTHOR]

Based on the variations of equivalent electrical permittivity with different phase concentrations in two-phase or multiphase flow, the capacitance sensor has been successfully used for the phase concentration measurement due to its advantages of non-invasion, low-cost, high reliability and non-radiation. However, solid particles are charged due to the collisions between particles and pipe wall in gas–solid flow system. The charge carried by solid particles will induce a certain amount of charge on the electrode of capacitance sensor, which causes an additional output in the capacitance measurement circuit. Hence, the particle electrification causes errors in capacitance measurements, and even leads to the failure of the measurement system for solid concentration and tomography system based on capacitance sensor. In this paper, the influence of particle electrification on the AC-based capacitance measurement circuit is theoretically and experimentally investigated based on a capacitance sensor with helical surface-plate electrodes. The results indicated that the capacitance signal and the electrostatic induction signal have different frequency band ranges. The influence of charge on capacitance measurements can be eliminated by rationally designing the capacitance measurement circuit, and further accurate and reliable capacitance measurement can be achieved. [ABSTRACT FROM AUTHOR]

Abstract: A multimodal tomography system based on the electrical capacitance and electrostatic sensor arrays is proposed to investigate the effects of particle charging in the pipe on electrical capacitance tomography (ECT). The effect of the charge in the pipe on the detection circuit of ECT is firstly analyzed. Then the simulations are performed to make further investigation on the effect of the charge distribution on ECT. The simulation results indicate that the electrostatic effects on ECT vary with the spatial distribution of the charge in the pipe. The charges near the pipe wall have greater effect on ECT than those in the center of the pipe. The capacitance electrode-pairs near the charge distribution are greatly affected. Experiments are also performed on a pulley rig, which verify the simulation results. [Copyright &y& Elsevier]

Abstract: Recently, great advance has been made on electrostatic sensing techniques for gas–solid flow measurement. However, reports on research studies of the sensing mechanism and characteristics of the electrostatic sensor arrays (ESA) are scarce. The ESA is a key element of the Electrostatic Tomography system (EST) and multi-channel electrostatic sensors for the local characteristic measurement of gas–solid flow. The geometric sizes of the ESA and the velocity and distribution of particles in the pipeline have important effects on the spatial sensitivity, spatial filtering effect and temporal frequency response of the ESA. In this paper, the charge induced on the electrodes of an ESA with different geometric sizes from a single particle having a unity charge is modelled mathematically, and the 3-dimensional electrostatic field due to the charged particle in the sensing zone of the ESA is solved by using a Finite Element Method. The effects of geometric and material parameters of the ESA, including the width and angel of the electrode, the thickness, length and permittivity of the dielectric pipe, the radius of metal screening on the sensing field of the electrodes are investigated numerically. Furthermore a computational model of the sensitivity of the ESA is proposed based on a fitted Gaussian function to the finite element results and its spatial filtering characteristics are also theoretically analyzed. The temporal frequency response of the ESA is also derived. Experimental work is performed on a purpose-built particle flow test rig to verify the modelling results. The theoretical and experimental results obtained demonstrate that the ESA acts as a low-pass filter in the spatial frequency domain. The measurement system, including the ESA and an interface circuit, acts as a band-pass filter. And the space position of charged particle, the electrode width and particle velocity affect the temporal frequency responses of the ESA. These results provide the basis for the performance improvement and optimized design of the ESA. [Copyright &y& Elsevier]