International Journal of Nanomanufacturing (57 papers in press)
Simulation of microstructure evolution coupled with fabrication parameters for two-phase ceramic tool materials
by Bin Fang, Chonghai Xu, Guangchun Xiao
Abstract: A computer simulation coupled with fabrication parameters for the sintering process of two-phase ceramic tool materials has been developed using a two-dimensional hexagon lattice model mapped from the realistic microstructure. The relationship between fabrication temperature and microstructure evolution, fabrication pressure and microstructure evolution is proposed， respectively. The mean grain size of simulated microstructures by Monte Carlo Potts model integrated with fabrication temperature and pressure increases with an increase in fabrication temperature and pressure, which is consistent with the experiment results. The microstructure evolution of ceramic tool materials during fabrication is simulated by the new Monte Carlo Potts model with considering technology parameters.
Keywords: Simulation; Hot-pressing sintering; Ceramic matrix composites (CMC); Microstructure; Monte Carlo model.
Research on Ice Fixed-abrasive Polishing Mechanism and Technology for High-Definition Display Panel Glass
by Yuli Sun, Suyang Tang, Wenzhuang Lu, Jun Li, Dunwen Zuo
Abstract: This study introduces an ice fixed-abrasive polishing (IFAP) technology. Using silica solution IFAP pad and Al2O3 IFAP pad, orthogonal tests were performed on polishing high-definition display panel glass, respectively. The results show that the polishing efficiency and effect polished with silica solution IFAP pad are better than those polished with Al2O3 IFAP pad. The optimized silica solution IFAP parameters are: polishing pressure 0.1MPa, polishing time 40min, table velocity 80r/min, and the ratio of accelerator and slurry 1:10. Finally, the IFAP mechanism was studied and it is suggested that IFAP is a comprehensive effect of mechanical removal and microchemical reaction, combined with fixed abrasive polishing and free abrasive polishing.
Keywords: Ice fixed-abrasive polishing; High-definition display panel glass; Material removal rate; Surface roughness.
Machining position-attitude optimization in ion beam figuring of high-precision off-axis aspheric surfaces
by Xu Mingjin
Abstract: High-precision off-axis aspheric components are widely applied in various high-performance optical systems. However, the complicated manufacturing features of off-axis aspheric make it difficult to achieve high-precision surface for traditional optical manufacturing methods. Ion beam figuring (IBF) is a non-contact and highly deterministic method for the final precision optical figuring. In this paper, two different machining position-attitude models are discussed, which have great influence on the machining difficulty and figuring accuracy of IBF. The Child mirror Coordinate Position-Attitude Model (CCPAM), which is based on the robustness of IBF removal function to small disturbance of target distance and incidence angle, can effectively decrease the sag height and incidence angle, thereby reduce the beam errors and machining difficulty. A linear three-axis IBF system is successfully applied for the figuring of a large-aperture parabolic off-axis aspheric mirror based on the CCPAM and its best-fit sphere. With two iterations of 113min, surface error is down to 7.658nm RMS (effective aperture 310mm
Keywords: Ion beam figuring; off-axis aspheric; machining position-attitude optimization; high-precision.
Surface Microstructure Parameter Optimization for Enhancing Light Extraction Efficiency of LED
by Dong Yuan, Xianyu Lin, Yanguo Liu, Guofu Zhou
Abstract: Surface structure modification is an effective way to enhance light extraction of LED, which is limited by total internal reflection on the interfacial surface. The periodic surface structures manufactured by micromachining was proved to be a feasible way to enhance the light extraction efficiency (LEE) of LEDs. In order to obtain the highest LEE, need to optimize the structural parameters. In this paper, a simplified ray tracing optical model was built to find out a high performance microstructure parameters by simulation. Then, a mathematical model was built to further optimize the optical simulation results, obtained the optimal microstructure parameters for LEE. The performance of optimal microstructure was also studied by optical simulation.
Keywords: LED; Microstructure; Light Extraction Efficiency(LEE); Structural Parameter Optimization; Micromachining.
Development of CNC Software for Single Point Diamond Precision Lathe Based on UMAC
by Xuehua Sun, Jianqun Liu, Weiqiang Gao, Guoqiang Huang, Huijing Huang
Abstract: ABSTRACT:rnA precise SPDT (Single Point Diamond Turning) CNC software is developed on the Windows platform using QT4.8.1 graphical interface development tools, with the calling of the UMAC library function. This paper introduces the hardware design of precise SPDT CNC system, the communication method between QT and UMAC, the design and implement of the main interface of the software, the implement of the basic motion control, the process of each module, the software three-dimensional (3D) simulation of this system. The result of the 3D simulation shows that the design of the system is reasonable, and the system is able to achieve good processing results. Such a numerical control system has a certain economic value and prospects for industrial applications. rn
Keywords: Keywords: SPDT; CNC Software; Qt; UMAC; Modularization.
Effect of single grit impacts on initiation and propagation of cracks in ultrasonic assisted grinding of ceramics by using SPH method
by Zhiqiang Liang, Meng Tian, Qiuyan Wang, Xibin Wang, Tianfeng Zhou, Jiao Li, Yongbo Wu
Abstract: In order to investigate the material removal mechanism in vertical ultrasonic assisted grinding (VUAG) of ceramics, single-grit impact simulation is performed by using smoothed particle hydrodynamics (SPH) method. The initiation and propagation of cracks in grinding of Al2O3 ceramics are analyzed. In this simulation, the grit is modeled as a rectangular pyramid diamond indenter, and the process of grit impacting on workpiece under different impact speeds is simulated. The critical depth of initiation and propagation of lateral crack is observed. The results show that within a certain range of impact speed, the critical depth of lateral crack decreases with the increasing of impact speed. This means that the brittle fractures are more prone to occur in VUAG. Considering that the material micro-fracture is the main mode in ceramics material grinding under ordinary processing conditions, the material removal rate in VUAG can be improved. Moreover, by observing the surface topography, it can be found that the surface roughness becomes smaller when the impact speed increases.
Keywords: Ultrasonic assisted grinding (UAG);Smoothed particle hydrodynamic method (SPH); Crack; Al2O3 ceramics.
Effects of cutting parameters on temperature and temperature prediction in micro-milling of Inconel718
by Xiaohong Lu, Hua Wang, Zhenyuan , Yixuan Feng, Steven Y. Liang
Abstract: Inconel 718 is a kind of difficult-to-machine material, and micro-milling is an effective method for fabricating micro structure/parts of Inconel 718. The change rules of micro-milling temperature differ from that of the traditional processing, which will affect the surface integrity of the workpiece and the tool life of the micro-milling cutter in different ways. To ascertain the effects of cutting parameters on cutting temperature during micro-milling and achieve the cutting temperature prediction, some micro-milling experiments were conducted based on the response surface method. The independent and interaction effects of spindle speed, feed per tooth and axial cutting depth on cutting temperature were investigated. A micro-milling temperature prediction model was established based on the experiment results. The maximum prediction error was 5.3%, and the average prediction error was 2.6%. Finally, the accuracy of the proposed model is validated through experiments of micro-milling Inconel718.
Keywords: Micro-milling; Cutting temperature; Inconel718; Response surface method.
Design and Simulation of Ultrasonic Horns in Ultrasonic Vibration Machining
by Meipeng Zhong, Julong Yuan, Weifeng Yao, Zhixiang Chen, Zhongdian Chen
Abstract: Ultrasonic horns are also called ultrasonic shift levers. They magnify ultrasonic vibration amplitude to meet the requirements of ultrasonic machining. To improve the efficiency of ultrasonic grinding, reduce the connecting parts of the lever, and reduce internal stress, the amplitude of the ultrasonic vibration process is defined in this study. The amplitude of the stress and modal simulation was determined using ANSYS was used as the simulation system for ultrasonic horn deformation. The stress and displacement at the end of the ultrasonic horns are the highest; however, the displacement at the node position of the flange is almost zero. The maximum displacement is 14.893
Keywords: amplitude; transformer; ultrasonic vibration; stress; modal.
Directivity Process Modelling for the Figure Error Correction of Dual-Rotation Magnetorheological Finishing
by Yuyue Wang, Yun Zhang, Zhijing Feng
Abstract: To study Dual-Rotation Magnetorheological Finishing (DRMRF) technology and obtain a smoother surface, the model for the polishing process of the figure error correction (directivity process model) in DRMRF was established in this paper. Existing researches ignored the influence of feed rate and revolution upon removal function. In this paper, a method of modifying the removal function is presented, which takes the relative velocity of the Magnetorheological fluid (MR fluid) and the part into consideration. The directivity of removal amount during modelling adds a new dimension for analysis. The numerical simulation results of removal amount and its directivity show that the removal amount distributed more evenly along every direction because of the revolution of the wheel in DRMRF. The removal amount distribution is one of the fundamental differences between common MRF and DRMRF. Finally, a Fused Silica planar blank was polished by DRMRF, and the initial figure error was 10 nm RMS and 67 nm PV. The surface figure error is corrected to 2.4 nm RMS and 20 nm PV (full aperture = 95% diameter), and the stripe-like scratches are suppressed. The numerical simulation results and the experimental result indicates the effectiveness of DRMRF and the correctness of directivity process model.
Keywords: Magnetorheological Finishing; Dual-Rotation Magnetorheological Finishing; Figure error correction; Directivity modelling; Optical fabrication.
Effect of FAP characteristics on fixed abrasive polishing of CaF2 crystal
by Jun Li, Yongkai Tang, Longlong Song, Yongwei Zhu, Dunwen Zuo
Abstract: Pad is an important factor, which bears pressure to mechanically remove material in chemical mechanical polishing process. Owing to the abrasives fixed in pad, fixed abrasive pad (FAP) becomes more important and influences material removal and surface quality of wafer. The characteristics of FAP, abrasive type, particle size and matrix hardness, were analyzed and the effect on material removal rate (MRR) and surface quality was investigated in fixed abrasive polishing of CaF2 crystal. The results indicated that FAP with 3-5
Keywords: Fixed abrasive polishing; Fixed abrasive pad (FAP); CaF2 crystal; Matrix hardness; FAP characteristics.
Developed greener method based on MW implementation in manufacturing CNFs
by Loai Aljerf, Rim Nadra
Abstract: Many researchers have worked to develop certain applications of carbon nanofibers (CNFs) materials. However, they faced primer obstacles related to the improper optimised conditions that mostly give heterogeneous surfaces with low product quality. Therefore, this study comes as the first trial that uses Microwave (MW) technique in combination with assisted chemical vapour deposition (CVD) to provide higher heating rates which will generate homogeneous surfaces at short period thermal reaction. The MW absorption properties were stimulated based on a model for a single-layer plane wave absorber. The model used for manufacturing process was validated to give better selectivity which then was verified by ANOVA statistical analysis. After that, the morphology, characterisation, and purity of the product were tested. The outcomes of this study had confirmed that these materials are of highly-ordered pyrolitic graphite nature and successfully proved the significance of the optimised model at elevated temperatures. CNFs were obtained having uniform diameters (80-150nm) and long fibres (0.82-1.75
Keywords: Greener nanoproducts; cosmetics; industry; homogeneous dispersion; electron diffraction pattern; pyrolysis; multi-walled structures; turbostratic stacking; azimuthal broadening; polymeric bonding.
3D surface roughness evaluation of surface topography in ultrasonic vibration assisted end grinding of SiCp/Al composites
by Li Zhou, Ming Zhou, Xiong Han, Jin Zhou
Abstract: In order to investigate the effect of ultrasonic vibration and cutting conditions on surface quality accurately, the grinding experiments of SiCp/Al composites were carried out. And a comprehensive analysis to characterize the machined surface topography with 3D roughness such as amplitude parameters and spatial parameters was presented. The experimental results indicate that the machined surface of ultrasonic vibration assisted end grinding is filled with peaks and dales and the surface texture is almost isotropic. Ultrasonic vibration can tremendously improve the machined surface performance, comparing with conditional grinding. And low surface roughness value can be obtained in the conditions of high spindle speed, large vibration amplitude, low feed rate and small cutting depth.
Keywords: ultrasonic vibration assisted end grinding; SiCp/Al composites; surface quality; 3D surface roughness; grinding conditions.
Analytical modelling of a tri-axial flexible capacitive tactile sensing array
by Jian-Ping Yu, Xin Li, Yu-Liang Zhang
Abstract: In this paper, the analytical modelling of a tri-axial flexible capacitive tactile sensing array is proposed. A unit sensing element consists of a sensing electrode layer, an insulation layer, a common electrode layer and a surface layer. The sensing electrode layer is of flexible printed circuit board (FPCB) based structure, on which, four sensing electrodes and fragile interconnects for signal sampling are implemented. While the common electrode layer is patterned on polydimethlysiloxane (PDMS) based structures, on which only a common electrode is implemented. This design is on purpose of enhancing the device flexible rigidity. Four sensing electrodes and a common electrode constitute four capacitors in a unit sensing element, when the four capacitors are arranged in a square form, the measured contact force will be easily decomposed into its normal and shear components. The estimated sensitivities of a unit sensor are 0.43 and 0.17%/mN for the x-y and z-axes, respectively.
Keywords: capacitive microsensor; three-dimensional tactile sensing; common electrode; PDMS.
Study on eddy current loss characteristics of precision giant magnetostrictive actuator considering magnetic field distribution
by HuiFang Liu, Shuang Gao
Abstract: In order to accurately calculate eddy current loss of the rod-shaped giant magnetostrictivematerial ,improve the giant magnetostrictive actuator control accuracy of displacement , a eddy current loss model of rod GMM that considering the skin effect was established.Firstly, the traditional eddy current loss of rod-shaped GMM was deduced ,then discussed the influence of the skin effect for the inside magnetic field distribution of GMM rod ,finally analyzed the temperature characteristics of GMA throught the comsolmultiphysics finite element numerical analysis method .Compared with traditional eddy current loss ,under low frequency the two methods has same result, but under high frequency the new model can be more accurately calculate the eddy current loss of rod-shaped GMM .The research result has a great significance for improving the control precision and advancing the study of eddy current loss of GMA.
Keywords: giant magnetostrictive actuator ,eddy current loss; temperature characteristics.
Forces, form deviations and surface roughness in micro-milling of CoCr alloys for dental prostheses
by Frederik Elsner-Dörge, Oltmann Riemer, Melanie Willert, Axel Meier
Abstract: Micro-milling is commonly used for the manufacture of dental prostheses. Demands to the application of these prostheses require hard and tough materials like cobalt-chrome alloys. The cutting process is governed by static as well as dynamic interactions between the process and the structure of the workpiece. These interactions deteriorate the work result, especially the shape accuracy. The deflection of the milling tool is one effect, which has a significant influence. The work presented in this paper aims to establish a connection between forces, respectively tool deflection and resulting form deviations during micro-milling of defined geometries in CoCr alloys by measuring the active forces and evaluating the resulting form. In order to quantify the surface quality, white light interferometry is applied to measure the surface roughness Sa and Sq and the influence of feed rate vf and radial infeed ae on the surface roughness is derived.
Keywords: force measurement; form deviation; micro-milling; dental prostheses; cobalt chrome; shape accuracy; surface roughness.
Review on Extrusion of Magnesium Matrix Nano Composites
by D. Anburose, N. Manikanda Prabu, V.S. Thangarasu, G. Sureshkannan
Abstract: Increase in industrial requirements focusing on various research activities on composite material in a narrow region. This is being observed through replacement of material components over an existing one due to its betterment in structure behaviour and properties. In recent days, Nano technology comes to play an essential part in composites and coating of material to upgradation of parameters. This work constitute the outlines and importance of extrusion process in magnesium matrix Nano composites, meanwhile the effect of various factors like temperature, grain size, extrusion speed, extrusion ratio etc., on enhancing the microstructure and mechanical properties of the magnesium matrix composites. The extruded components have more excellent properties such as tensile strength, proof stress and elongation than the cast components. Addition of Nano particles may lead to significant inhibition in grain boundaries resulting in refined grains after extrusion resulting in high strength of the composites. Nano particles can significantly increase the mechanical strength of magnesium matrix by effectively promoting particle hardening mechanism than micro size particles.
Keywords: Magnesium matrix Nano composites; Nano particles; Extrusion process; dynamically re-crystallized grains.
An error separation method based on surface matching in large aspheric measurement
by Lin Sun, Shuming Yang, Pengfei Wu, Changsheng Li, Qijing Lin, Zhuangde Jiang
Abstract: Surface matching technique is the base of three-dimension surface error separation, which plays an important role in error compensation of ultra-precision manufacturing and automatic feedback control system. Surface error and surface roughness are key indicators for the evaluation of the quality of optical elements ultra-precision manufacturing. There are variations between the measured data and the actual surface data due to clamped positioning errors. Therefore, it is difficult to improve the manufacturing precision by error compensation based on evaluating the deviation between the measured data and the theoretical surface data directly. So we proposed an error separation technique based on surface matching, which can match the surface generated by fitting the measured data with the theoretical surface. And then we can obtain the spatial transformation parameters between measured surface and the actual surface using GA(Genetic Algorithm) for optimizing. Finally we can separate the spatial errors resulting from the clamped positioning errors of the measurement, and the actual measured surface errors are got.
Keywords: Surface matching; Error separation; Genetic Algorithm; Clamped positioning errors.
Influence of oxygen vacancies on the spontaneous polarization and piezoelectricity of ZnO: A first-principles study
by Haibo Niu
Abstract: By using the Berry phase methods, influence of oxygen vacancyrn(Vo) on the polarization property of ZnO has been investigated. Calculateed results indicate that the spontaneous polarization, the piezoelectric constants e31 and e33 are very sensitive to the concentration and distribution of Vo. The absolute values of them decrease nonlinearly as the Vo concentration increases. At the same concentration, non-uniform distribution of Vo is favored in energy, and can enhance the impact on spontaneous polarization and e31. 1.56% Vo-Vo complex can even reverse the orientation of spontaneous polarization, while the case for e33 is opposite, the influence is weakened. These findings suggest that the polarization property of ZnO might be adjusted by controlling the point defects.
Keywords: Oxygen Vacancy; Spontaneous Polarization; Piezoelectric Constants; Berry Phase; Maximally Localized Wannier functions; First Principles.
Research on temperature distribution mathematical model of cutting tool during heavy cutting difficult-to-machine materials
by Yaonan Cheng
Abstract: Heavy cutting is the main machining way for high-end equipment and the high temperature generated from the cutting process largely influences on the machining and tool life. Firstly, the main cutting area where energy was converted into cutting heat and the approximate rectangular distribution of cutting temperature were received through Finite Element Simulation of heavy cutting difficult-to-machine materials and the Finite Element Simulation provided fundamental basis for temperature distribution mathematical model. Then, heavy cutting characteristics and Jaeger moving heat source theory were combined to calculate the average temperature of shearing surface and rake face of the cutting tool. Finally, temperature distribution mathematical model in tool-chip contact area for heavy cutting difficult-to-machine materials was established using Kelren theory. The results show that the established mathematical model are consistent with experiment results and the model provides theoretical basis for quantitative analysis of heavy cutting temperature, the optimization of cutting parameters and heavy cutting tool design.
Keywords: cutting temperature; mathematical model; heavy cutting; difficult-to-machine materials.
Fractional-order composite control for the transient creep of a piezoelectric actuator
by Xueliang Zhao, Chengjin Zhang, Hongbo Liu
Abstract: In this study, a fractional-order composite controller is proposed to decrease the settling time and narrow the range of the transient creep of a piezoelectric actuator. The controller is composed of backlash modules and a fractional-order PI_λ controller. The backlash modules reduce the effect of the transient creep and the hysteresis, while the fractional-order controller decreases the settling time. Experiments show that the settling time is decreased from 11 ms to 6 ms. The controller exhibits good performance on step creep and hysteresis when the input signal is discretized into steps, whether 10, 20, 40 or 80 steps. All standard deviations are suppressed to levels 39.3% lower than that of a standard PI controller, and the range of the transient creep is reduced to 19.46%.
Keywords: piezoelectric actuator; dynamic creep; transient stage; fractional order; hysteresis.
The Material Design and Property Research of a Novel Machine Tool Material
by Bin Lin, Zehua Hu
Abstract: In this paper, a new machine tool material is put forward where PTFE resin is chosen as the matrix material for its properties of good acid and alkali corrosion resistance. High purity quartz and alumina ceramic microspherernare selected as the aggregates; nano-alumina and hollow glass microsphere are selected as the fillers. First, the aggregate gradation is analysed. Then, Young's modulus and sound attenuation coefficient are predicted in theory. Nonlinear regression analysis is conducted by Support Vector Machine (SVM). A 2D and 3D irregular polygon aggregate particles packing model is set up by MATLAB and the properties of the packing model are simulated by finite element analysis. Finally, several vibration experiments are conducted. The analysis results show that the chosen filler and aggregate can improve the stiffness and vibration characteristics of the material, which has a guiding significance to the machinery manufacturing industry.
Keywords: machine tool material; PTFE; high purity quartz; alumina ceramic microsphere; nano-alumina; hollow glass microsphere; Young's modulus; sound attenuation coefficient; nonlinear regression analysis; particle packing model; damping ratio.
Carbon nanotubes synthesis using Fe-Co-Mo/MgO tri-metallic catalyst: study the effect of reaction temperature, reaction time and catalyst weight
by Puguh Setyopratomo, Praswasti PDK Wulan, Mahmud Sudibandriyo
Abstract: MgO supported tri-metallic catalyst containing combination of transition metals Fe, Co, and Mo was used to synthesize carbon nanotubes (CNT) from liquefied petroleum gas by chemical vapor deposition (CVD) method. The effect of reaction temperature, reaction time and catalyst weight to the yield and the CNT properties was investigated. It found that the CNT yield increased with increasing the reaction temperature. Besides, increasing the reaction temperature lead to the increase of the diameter and wall thickness of the CNT. Moreover, it was found that the crystallinity of the synthesized CNT increase when the reaction temperature is raised. The yield is steadily increased with increasing reaction time and reach the highest yield at 21.95 g CNT/g catalyst which corresponds to reaction time 5 hours. The micro pores volume, BJH pores volume and total pores volume, all show a decrease when the reaction time is increased. The meso pores dominate the pore structure of the CNT product and contribute around 90 % of the total pores volume. Meanwhile, micro pores with pore size range around 0.3-0.4 nm dominate the micro pores and contribute approximately 50-60 % of the total micro pores volume. It also found that the CNT yield is decreased along with the increasing catalyst weight.
Keywords: carbon nanotubes; reaction time; reaction temperature; yield; liquefied petroleum gas; supported catalyst.
Fractal Description and Adsorption-Desorption Behavior of Coke Treated by Benzene pyrolysis carbons
by Zezhi Zhang
Abstract: For explaining why benzene pyrolysis carbons could inhibit coke deterioration in blast furnace, the adsorption-desorption data of coke sample treated by benzene pyrolysis carbons were obtained to establish adsorption-desorption isotherms and to fit fractal description model with Frenkel-Halsey-Hill equation. The SEM photographs of coke revealed that the pores of the infiltrated coke were almost filled with pyrolysis carbon particles. The fitted curves showed that the types of isotherms were similar to type II of IUPAC classification, and the hysteresis loops belonged to type H3 which represents a typical multilayer adsorption. Model tests indicated that the pore structure of the coke samples have obvious fractal feature and the fractal dimensions of coke sample treated by benzene pyrolysis carbons were smaller than that of original coke sample. So, it explained that benzene pyrolysis carbons can effectively inhibit coke deterioration by infiltrating into the pore structure of coke and reducing pore roughness.
Keywords: coke; inhibition deterioration; benzene pyrolysis carbons; adsorption-desorption; fractal description.
Precision of prestressed ball screw thermal behaviour in machine tool operating conditions
by Zbigniew Kowal, Jerzy Jedrzejewski, Taeweon Gim
Abstract: This paper presents an FEM model of a feed drive with a ball screw stiffness-wise, thermally and motion-wise integrated with the machine tool structure. The model takes into account the moving heat sources, the frictional and inertial interaction of the masses being shifted and the variable thermoelastic and stiffness interactions within the drive and the machine tool load-bearing structure. The results of heating up and displacement calculations for the ball screw, the bearing supports and the whole machine tool are analyzed with regard to positioning accuracy.
Keywords: machine tool; ball screw; model.
Study on engineering module design for liquid macromolecular ingredient content detection
by Xiaotong Na, Zhen Zhou, Chunyu Wang, Jia QI
Abstract: The liquid milk with the main ingredients of protein and fat was used as the research background for liquid macromolecular ingredient content detection in this paper. A model for the protein and fat ingredient content was established with the theory of scattered through ratio. Based on this, the photoelectric detection module was designed. Multiple photoelectric detection module circuit boards had been tested, the average error of the scattered light direction photoelectric detection circuit was 0.0072, and the average error of the photoelectric detection circuit in the direction of transmission light was 0.0094. The correlation coefficient of the established model can reach 0.97, and the system measurement uncertainty is about 0.078. The above test results show that the design meet the engineering application indicators basically. The detection module designed in this paper had the convenience, fast and efficient real-time performance, the reproducibility and stability was satisfactory.
Keywords: ingredient content detection; liquid macromolecular; engineering; module design; scattered through ratio.
INFLUENCE OF BORON NITRIDE NANO ADDITIVES IN CUTTING FLUID FOR IMPROVING SURFACE ROUGHNESS WITH MRR
by Manikanda Prabu Narayanasamy, Maniiarasan P, Nallusamy S, Jeevanantham S
Abstract: Surface quality of machined component is the essential requirement in industrial sectors by focusing on customer needs. Under this consideration, lot of researches brought in to proven results to enhance the surface quality in various machining Centre in different ways. Surface quality depends on the certain machining parameters which may have direct impact on output parameters such as surface roughness, MRR and indirectly correlated with the frictional resistance and heat transfer characteristics due to the relative motion of work and tool material. Previous results discussed the reduction state of frictional characteristics of machining in which selection of cutting fluids plays a vital role in reducing frictional resistance between tool and work. At present, quality and machining characteristics of cutting fluids attain better focus in such a way to improve the surface finish using additives and obviously Nano additives are assumed to be a possible solution to provide betterment of machining outcome. Present experimental work discusses the Preparation of Nano cutting fluids using boron nitride, Characteristics and influence on Machining parameters such as MRR, Tool life particularly surface quality in surface grinding operation. Result revealed that the addition of boron nitride Nano particles with base fluid is providing greater surface finish when compared to the conventional cutting fluids.
Keywords: Cutting Fluid; Grinding; Nano Additive; Surface Finish; MRR.
The behavior of nanofluids flooded in printed mini channels when excited by a small electrical potential
by Ahmad Yusairi Bani Hashim, Azri Nazran Afandi, Imran Syakir Mohamad, Syazwani Zainal Abidin, Amirah Abdullah
Abstract: This work sought to observe the response of a nanofluid put along in an electrical circuit while seeing the behavior of the fluid. Would the nanofluids have a characteristic of an electrolyte? Two mini channels were constructed using additive manufacturing approach. The nanofluids were flooded in the channels where they were connected in series with a generic resistor in a low voltage circuit. The fluids behaviors were observed through the recorded voltage drops at the resistor and also at the channels start and end points, respectively. The results showed minute currents were flowing in the circuit as the fluids recorded high resistances. Therefore, the nanofluids are naturally high resistance electrolytes. However, the real nature of the fluids exposed to electrical potentials for a longer duration is unknown.
Keywords: Mini channel; hydraulic diameter; carbon nanotube; carbon nanofiber; electrical conductivity; 3D printing; high resistance electrolyte.
Tailoring of Nanoparticles for Chemical Enhanced Oil Recovery Activities: A Review
by Augustine Agi, Radzuan Junin, Afeez Gbadamosi
Abstract: Nanotechnology has found its way to Petroleum Engineering, as it is a well-accepted path in the oil and gas industry to recover more oil trapped in the reservoir. The challenge in nanotechnology in the oil and gas industry is full-scale field application, due to cost. A considerable research and development investment is needed for the implementation of the technology in formulating cheap, readily available and environmentally friendly nanoparticles. In this review, methods of synthesizing the different types of nanoparticles is described, detailing the parameters involved in these techniques with the aim of tailoring their distinct properties such as; large surface area and ability to manipulate their behaviour for enhanced oil recovery. The difference between the natural and synthetic polymer nanoparticles and their various method of synthesis is discussed and their advantage in enhanced oil recovery is highlighted. The methods of synthesis can lower the interfacial adsorption of polymer with surface-active properties, prevent aggregation when the nanoparticle is subjected to flow, and prevent degradation. It can also form micelles and liposomes which can lower critical micelle concentration (CMC) and influence phase behaviour. The challenges encountered have opened new frontier for research and are also highlighted herein.
Keywords: Nanotechnology; Nanoparticle; Synthesis; Chemical Enhanced Oil Recovery; Polymer.
Tolerance Analysis of Slider-crank Mechanism for Assembly Functionality Check
by XUSONG XU
Abstract: Tolerance analysis is an effective way to improve the quality and decrease the cost of product. Functionality check is an important aspect of tolerance analysis. The purpose of functionality check is to analyse the stack-up of geometric deviation of part/feature whether it meets the demand of geometry and is it in the range of assembly tolerance. Geometric variations exist in the process of tolerance stack-up and transmission, on the other hand, the part itself has geometric error. In addition, since geometric deviation exists in the assembly feature between the parts, so the objects of tolerance analysis should contain part tolerance and assembly clearance. However, the usual tolerance analysis model does not include the assembly clearance. Aiming at this problem, we have done some research. Firstly, the nominal geometric transfer model and the stack-up model are established based on the Small Displacement Torsor(SDT) and Homogeneous Transformation Matrix(HTM). Secondly, HTM expression of the tolerance loop is constructed. Next, the assembly tolerance analysis matrix model is established and a new tolerance analysis method for assembling feasibility is put forward. The main advantages of the method are: 1) analysis object not only contains the tolerance, but also contains the assembly clearance; 2) it can analyse the stack-up deviation of the multiple assembly clearance; 3) it can effectively perform the assembly functionality check and the evaluation of the tolerance allocation results. At last, taking slider-crank mechanism as an example, the contrastive study of tolerance analysis for functionality check is done after establishing stack-up model of assembly tolerance analysis. The results show that it is prone to lead to misjudge when analysing only dimension tolerance, the analysis results of considering dimension tolerance, geometric tolerance and assembly clearance are more restrictively. However, it is more compliance with actual engineering.
Keywords: Tolerance analysis; Assembly tolerance; Tolerance stack-up model; Assembly clearance; Slider-crank Mechanism.
An Approach to Calculate Master Curve for Glass Molding Press Based on Finite Element Simulation
by Zhiguo Zhang, Yuxuan Sun
Abstract: A new approach is proposed to calculate the master curve (MC) of glass. It can solve the problem: when the temperature is higher than T_(t,l) (defined later), the measured shear relaxation modulus cant describe the mechanical response of the annealing stage during glass molding press(GMP) through the thermal rheological simple (TRS) theory. Based on the temperature dependent Yang's modulus and TRS theory, the MC with a reference temperature less than T_(t,l) is calculated by an iterative process.In order to verify the suitability of MC at high temperature, the MC and shear relaxation moduli are used in the finite element(FE) simulation at the isothermal compression stage. Similar von Mises stresses are shown and the usability of the MC at molding temperature is proved by the simulation results. In order to predict residual stress within the formed glass lens, the MC is used to conduct FE simulation for the whole GMP process.
Keywords: Glass molding press; Viscoelasticity; Thermal rheological simple; Master curve; Finite element.
Study on Novel Temperature Sensor based on Amorphous Carbon Film
by Qi Zhang, Xin Ma, Meiling Guo, Lei Yang, Yulong Zhao
Abstract: In this study, a new type of thermistor temperature sensor was developed. The sensing materials was amorphous carbon (a-C) film prepared using electron cyclotron resonance (ECR) plasma processing system under low energy electron irradiation sputtering. The nanostructure of a-C film was observed by transmission electron microscope (TEM), the atomic bonding and carbon hybridization condition was analyzed by Raman spectra and X-ray photoelectron spectroscopy (XPS) respectively. The linearity of temperature-resistance curve of this kind of a-C film was very good in certain temperature range, with high temperature coefficient of resistance (TCR). The a-C film by 50 eV electron irradiation can measure larger temperature range from -75 degree centigrade to 155 degree centigrade, with good repeatability. The working temperature range of a-C film by 100 eV electron irradiation was much smaller, but TCR absolute value of this film was higher. It can be concluded that the lower sp2 / sp3, the better linearity of temperature-resistance curve, the lower TCR absolute value in certain working temperature range. The research shows that this kind of a-C film temperature sensor has good linearity and repeatability, also it can be integrated with other MEMS sensor simply.
Keywords: Amorphous carbon film; Thermistor; Temperature sensor; Temperature resistance characterization; Temperature coefficient of resistance.
One Step Synthesis of ZnO Nanoparticles with Zinc Acetate Dehydrates and Potassium
by Md. Zaved Hossain Khan, Partha P. Das, Md. Abdullah
Abstract: In this study, pure ZnO nanoparticles have been synthesized by one step method where zinc acetate dehydrates and potassium use as a precursor. The UV-vis absorption spectrum was indicated that the reduction and stabilization of ZnO nanoparticles in aqueous medium. The peaks in X-ray diffraction pattern were revealed that the formation of ZnO in nanoscale and it good treaty with that of crystalline hexagonal structure. It was observed that ZnO elicited in form of nanoparticles and nanoflowers in spherical shape as well as homogeneous dispersion. The grain size were found to be 18-40nm. Thermo gravimetric analysis and Diffractive thermal analysis results were showed the thermal stability of ZnO nanoparticles in the temperature region of room temperature to 10000C. FTIR measurement was revealed that the synthesized Zn ion have potential interaction towards organic aqueous fluid to form of ZnO nanoparticles.
Keywords: ZnO nanoparticles; ZnO nanoflowers; crystalline structure; morphology; thermal analysis.
The Use Of Surface Plasmon Resonance Band Of Green Silver Nanoparticles and Conductometry For Quantitative Determination Of Minor Concentrations of Doxycycline hyclate And Oxytetracycline HCl in Pure and Pharmaceutical Dosage Forms.
by Rania A. Sayed, Manal S. El- Masry, Wafaa S. Hassan, Magda Y. El-Mammli, Abdalla Shalaby
Abstract: Two novel and sensitive methods for quantitative determination of doxycycline hyclate and oxytetracycline HCl were developed. The first method (Method A) is based on the reducing character of the cited drugs which causes chemical reduction of silver ions to silver nanoparticles (Ag-NPs) in the presence of polyvinyl pyrrolidone (PVP) as a stabilizing agent producing surface plasmon resonance which has absorption peaks at 424 and 428 nm for doxycycline hyclate and oxytetracycline HCl, respectively. The nanoparticles were characterized by UV-VIS spectrophotometry and transmission electron microscopy (TEM). The plasmon absorbance of the Ag-NPs was used for the quantitative spectrophotometric determination of the cited drugs. The second method (Method B) is a conductometric method which is based on the reaction of the cited drugs with phosphotungstic acid to form ion associates in aqueous system. Validation of the proposed methods was carried out.
Keywords: Silver nanoparticles; doxycycline hyclate; oxytetracycline HCl; conductometry and phosphotungstic acid.
Design and Simulation of MEMS Piezoelectric Vibration Energy Harvesters with Center Mass Block
by Lu Wang, Dejiang Lu, Shenrong Zhang, Zhikang Li, Yong Xia, Yunyun Luo, Libo Zhao, Zhuangde Jiang
Abstract: Abstract: MEMS-based piezoelectric vibration energy harvesters (MEMS-PVEHs) with center mass block are designed with the overall size 10102 mm3, two prototypes including piezoelectric unimorph and bimorph beams are used respectively. The MEMS-PVEHs have a lower resonant frequency (109.20Hz for unimorph beam and 84.80Hz for bimorph beam), and high optimal mechanical and piezoelectric power density (22.30mW/(g2cm3) for unimorph and 29.02mW/(g2cm3) for bimorph beam). This paper studies the characteristics of MEMS-PVEHs by modeling and simulation in COMSOL. Their eigenfrequencies are analyzed firstly, their optimal piezoelectric outputs are explored by changing excitation frequency and load resistance secondly, then the piezoelectric unimorph & bimorph beams are compared finally. The simulation results show that the optimal excitation frequency is slightly higher than the eigenfrequency, and the maximum piezoelectric power of the PVEH can be obtained only when the appropriate excitation frequency and load resistance are selected, and the power generation efficiency is 0.5. By comparing the unimorph and bimorph beams, it is suggested that the unimorph and bimorph MEMS-PVEHs should be designed to improve the piezoelectric output by decreasing resonant frequency and increasing input mechanical power. Finally, the piezoelectric unimorph with double opposite electrodes is designed based on the MEMS fabrication process.
Keywords: Energy harvesting; Piezoelectric; MEMS; Resonant frequency; Power optimization.
Preparation and characterization of nanokaolinite photocatalyst for removal of P-nitrophenol under UV irradiation
by Said El-Sheikh
Abstract: A nanokaolinite photocatalyst was prepared successfully using intercalating method which depends on insertion of chemical reagent between bulk kaolinite layers followed by delamination process. The as-prepared nanokaolinite photocatalysts were characterized by X-ray diffraction, FTIR analysis, Transmission electron microscope (TEM) and UV-vis diffuse reflectance spectroscopy. XRD data show that the crystals size of exfoliated nanokaolinite in the range ~ 26-32 nm. FTIR peaks assign to presence of nitrogen between nanokaolinite layers, which maybe lead to decrease the band gap of prepared samples. The photocatalytic activity of nanokaolinite photocatalysts was investigated by degradation of PNP under ultra-violet irradiation. The ideal nanokaolinite sample (K/urea) show extraordinary photocatalytic activity (100%) toward PNP within 30 min. due to its enhanced band gap value.
Keywords: Delamination; Kaolinite; phyllosilicates family; Intercalation; Photodegradation; P-nitrophenol; Paper filler; Photocatalytic activity.
Research on processing technology of grinding aspheric workpiece in the five-axis machine tool
by Jianfeng Liu
Abstract: Aspheric optical components have been widely used recently because of their unique advantages. Thus, it is necessary to investigate processing technology of such aspheric parts. In this paper, an aspherical mirror is ground with cup wheel in five-axis CNC (Computer Numerical Control) machine tool and corresponding processes were investigated. To improve machining efficiency and reduce tool wear, the workpiece is firstly ground to be a spherical mirror, and then it is ground to be the aspheric contour. The best fitting spherical mathematical equation is derived by the axisymmetric quadratic aspheric generatrix equation. A aspheric mirror was ground with cup wheel with five-axis CNC (Computer Numerical Control) machine tool. The aspheric curve is processed into a paraboloid shape. The experimental results show that the surface profile of the aspherical lens is consistent with the designed profile, and the PV (Peak Value) value of the error is . Such results can be accepted in consideration of working allowance for polishing. According to the experimental results, the cause of the error was analyzed and methods for improving precision were proposed.
Keywords: five-axis machine tool; cup wheel; aspheric surface; fitting spherical radius
Special Issue on: ICEM 3-2017 New Energy Materials and Nanotechnology Modelling and Experiment
Hollow microellipsoid lithium silicate with mesoporosity and its formation mechanism
by Jing Gao, Mingxing Tong, Wei Lei, Xuan Zhang, Guohua Li
Abstract: Lithium silicate is an important sorbent to capture CO2. Herein hollow microellipsoids of lithium silicate with mesoporosity were prepared by a hydrothermal method using Na-montmorillonite and lithium hydrate as raw materials. X-ray diffraction, scanning electron microscope and transmission electron microscope analysis show that the crystal phase of the products is composed of lithium silicate and the particle morphology of the sample is hollow microellipsoid at around 600 nm. Furthermore, the wall of the microellipsoid is constituted of mesopores and nanoparticles with a size range within 20 to 40 nm. The specific area and aperture of the samples measured by BrunauerEmmettTeller method is 32.3 m2g-1 and 17.1 nm, respectively. Finally, a formation mechanism of the hollow microellipsoid was proposed to guide further exploration.
Keywords: hollow microellipsoid; lithium silicate; mesoporosity; formation mechanism.
Preparation and characterization of cMWCNTs-mSA/mCS bipolar membrane for electrochemical synthesis
by Suyu Shi, Lina Wang, Kang Zhao, Chuntai Liu, Guoqiang Zheng
Abstract: In this study, a bipolar membrane (BPM) of sodium alginate (SA) and chitosan (CS) was prepared based on carboxyl multi-walled carbon nanotubes (cMWCNTs). To improve the compatibility of anion-exchange layer and cation-exchange layer, polyvinyl alcohol (PVA) was blended with both the SA and CS, respectively. A casting method was employed to prepare the modified BPM named as cMWCNTs-mSA/mCS BPM for simplicity. The morphology, thermal and structure stability, electrochemical properties and ion penetrability of the BPM were characterized. Scanning electron microscopy (SEM) images illustrate a structure consisting of two distinct layers that are closely combined with each other. Thermal gravimetric (TG) results indicate that the thermal stability of cMWCNTs-mSA/mCS BPM is significantly improved. Swelling behavior implies a proper hydrophilic performance and excellent structure stability in alkali solution. Compared with SA/CS BPM, the working voltage of cMWCNTs-mSA/mCS BPM is decreased sharply. Furthermore, the cMWCNTs-mSA/mCS BPM exhibited higher ion penetrability which is beneficial for electrochemical synthesis.
Keywords: bipolar membrane; sodium alginate; chitosan; carboxyl multi-walled carbon nanotubes.
The effect of nano-Zirconia on the morphology and mechanical properties of PVDF/PAN membrane as separators in super-capacitors
by Wang Lina, Shi Suyu, Liu Wentao, Zong Dingding
Abstract: The PVDF/PAN/ZrO2 composite fibrous membranes were fabricated by electrospinning. The effects of ZrO2 content on solution properties, mechanical properties and crystallization properties as well as related morphology were systematically evaluated. The SEM images show that the diameter of the fibers is only 0.8 um when the ZrO2 content is 0.4% which is the result of the ZrO2 improving the conductivity of the PVDF/PAN solution. The BET results show that the specific surface area of PVDF/PAN/ZrO2 with 0.4% ZrO2 is 1.8 times of PVDF/PAN membrane. The tensile strength of fibrous membranes increased from 2.74 of pure PVDF/PAN to 5.11 MPa of PVDF/PAN/ZrO2 when the ZrO2 is o.4%. The DSC results show that the crystallinity and orientation enhanced with ZrO2 increases, which is beneficial to improve the tensile strength. The Tg and Tc shift to high temperature with ZrO2 increases, which demonstrating that ZrO2 promote the heterogeneous nucleation and form perfect crystal structure.
Keywords: Poly (vinylidene fluoride);Polyacrylonitrile;nano-zirconia;supercapacitor separators;morphology;mechanical properties.
One-dimensional Z-scheme TiO2/WO3 composite nanofibers for enhanced photocatalytic activity of hydrogen production
by Dongyang Wan, Peng Zhang, Jiangtao Zhao, Junhua Hu, Guosheng Shao
Abstract: TiO2/WO3 composite nanofibers were fabricated by electrospining and calcine. The as-prepared composite nanofibes were characterized by scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy, respectively. The results indicated that the TiO2/WO3 composite nanofibers were successfully fabricated, and the H2-generation of the as-fabricated TiO2/WO3 composite nanofibers were significantly enhangced comparing with pure TiO2 nanofibers. The enhanced photocatalytic activities were mainly due to the addition of WO3. which acted as a hole collector, leading to effective charge transfer. More importantly, the improvement of photocatalytic activity of TiO2/WO3 composite nanofibers were proved by photocurrent and electrochemical impedance spectroscopy.
Keywords: Electrospinning; Composite nanofibers; H2-generation; Photocatalytic activity.
Special Issue on: IJNM ICEM 3-2017 New Energy Materials and Nanotechnology Modelling and Experiment
Multiferroic properties of Mn-doped Bi4NdTi3FeO15 ceramics
by Qingqing Ma, Yahui Shu, Lin Cao, Zhenzhong Ding, Feng Huang
Abstract: Ceramics of Mn-doped Bi4NdTi3Fe1-xMnxO15 (Mnx, x=0.1, 0.3, 0.5 and 0.7) were synthesized by a multicalcination procedure. The substitution of Mn for Fe does not change the layered perovskite structure of Bi4NdTi3FeO15 (BNTF) except that small amounts of Mn3O4 appear in the samples. Plate-like morphology of the grains which is characteristic for layer-structure Aurivillius compounds was clearly observed for all the Mnx samples. The dielectric, ferroelectric and magentic properties of the samples were studied and it is found that the doping of Mn weakened the electric properties but improved the magnetic property. Especially, in Mn0.3 sample, the 2Mr value is about 10 times of those in other samples. The present work is meaningful for compositional design of room temperature (RT) multiferroic materials based on four-layer structured Aurivillius compounds.
Keywords: Aurivillius phase; multiferroic; Bi4NdTi3FeO15; Mn-doping.
Molecular dynamics simulation of shear deformation of multi-layer graphene sheets with Tersoff potential
by Xiaoxi Zhao, Yizhe Zhang, Yongchi Li, Wei Liu
Abstract: The failure process of multi-layer graphene sheets with AB stacking order under shear deformation is simulated using molecular dynamics method with Tersoff potential. Shear stress-strain relationships and shear failure modes of zigzag and armchair graphene sheets are obtained, while the effect of the number of graphene layers on the shear properties of zigzag and armchair graphene sheets is investigated. The results indicate that the shear modulus of graphene sheets is inclined to diverge with the increase of the number of graphene layers. Moreover, the ultimate stress and shear failure strain of zigzag and armchair graphene sheets are reduced gradually with the increase of the number of graphene layers.
Keywords: multi-layer graphene; shear modulus; molecular dynamics; failure mode; Tersoff potential.
The luminescent properties of GdAlO3:Tb3+ phosphors based on molten salts addition
by Jinkai Li, Wenzhi Wang, Zongming Liu
Abstract: The (Gd1-xTbx)AlO3 (x=0-0.12) solid solutions were obtained through precursor synthesis via ammonium bicarbonate co-precipitation technology, and then calcined at high temperature. The performance characterizations of GdAlO3:Tb3+ phosphors were performed by XRD, FE-SEM, PLE/PL and fluorescence decay analysis. The analyzed results indicated that the pure-phase (Gd1-xTbx)AlO3 solid solutions with good dispersion could be obtained at relatively lower temperature of 1000 oC. Under the optimum UV excitation into 275 nm (4f8-4f75d1 transition of Tb3+), the photoluminescence (PL) spectra display a series of 5D4-7FJ transitions of Tb3+ in (Gd1-xTbx)AlO3 system with the strongest green emission at ~546 nm (5D4-7F5 transition of Tb3+). The overlapping between the 8S7/2-6IJ intra f-f transition of Gd3+ and 4f8-4f75d1 transition of Tb3+ at 275 nm, suggesting the Gd3+→Tb3+ energy transfer, and the quenching contents of Tb3+ was found to be ~10 at%. The luminescent property of GdAlO3:Tb3+ phosphor could be further improved with molten salt incorporation due to the crystalline perfection. According to the comprehensive analysis, the optimal composition of molten salts for GdAlO3 based phosphors was obtained in this work, the optimal molten salt was determined to be the mixture of NaCl/Na2SO4 (5 wt% NaCl), and the mass ratio of mixture molten salts to precursor was 2:1. The relationship between the luminescent property (emission intensity and lifetime) and molten salts composition were studied in detail. The (Gd1-xTbx)AlO3 phosphors with good luminescent property could be widely used in the lighting and display areas.
Keywords: GdAlO3:Tb3+ phosphor; energy transfer; molten salts; luminescent property.
Preparation of poly(3-hydroxybutyrateco-3-hydroxyvalerate) (PHBV) supported cobalt phthalocyanine thin membranes and its catalytic degradation of methylene blue
by Minhong Xu, Haifeng Chen, Guoxiang Pan, Yuhua Guo, Tao Wu
Abstract: The supported catalyst membranes (CoPc/PHBV) were prepared by solution casting method with tetracarboxyphthalocynine cobalt (CoPc) and poly(3-hydroxybutyrateco-3-hydroxyvalerate) (PHBV). The membranes were characterized by scanning electron microscope, X ray diffractometer and fourier transform infrared spectroscopy. The results indicate that CoPc and PHBV may be combined by physical, and the crystal structure of PHBV which loaded CoPc is not changed. In addition, the catalytic performances of CoPc/PHBV were evaluated by degradation of methylene blue (MB). The results reveal that CoPc/PHBV and H2O2 have significant synergistic effect on catalytic degradation of MB, and degradation efficiency is 73 % after 7 h. Hydroxyl radicals play a key role in catalytic degradation of MB based on the study of reaction mechanism. The dynamics about catalytic oxidation of MB were also explored. The results show that catalytic degradation process fits well with first-order kinetic equation.
Keywords: cobalt phthalocyanine; PHBV; catalytic degradation; methylene blue; synergistic effect.
Photocatalytic properties of magnesium aluminate spinel nanoparticles prepared by chemical precipitation method
by Hui Li, Yuqin Liu, Ji Chen, Da Chen, Junkai Tang, Yanxi Deng
Abstract: Magnesium aluminate spinel nanoparticles were synthesized via chemical precipitation method using ammonia as precipitating agent. The effects of calcination temperature on the phase constitution, morphologies, specific surface area and photocatalytic properties were investigated. Single phase cubic MgAl2O4 formed by calcining the precursors at the temperature ranges from 700 oC to 1000 oC for 90 min. The mean crystallite size of the MgAl2O4 powder increases slightly with the increase in calcination temperature. Increasing the calcination temperature leads to decrease in the specific surface area and the decline of the photocatalytic properties. The methylene blue removal ratio reaches 96.3 % within 240 min using MgAl2O4 spinel powder calcined at 700 oC.
Keywords: magnesium aluminate spinel; chemical precipitation synthesis; photocatalytic properties; calcination.
Experimental investigation on the surface tension and contact angle of Al2O3-oil and SiO2-oil nanofluids
by Yue Li, Weilin Zhao, Yuying Gong
Abstract: The experimental results regarding the surface tension and contact angle of Al2O3-oil and SiO2-oil nanofluids with 0.1%-1.0% volume fraction at the temperature of 25
Keywords: Al2O3-oil nanofluids; SiO2-oil nanofluids; surface tension; contact angle.
Growth of NiCo2O4 Nanotubes @MnO2 Sheet Core-Shell Arrays on 3D Hierarchical Porous Carbon Aerogels as Superior Electrodes for Supercapacitors
by Huili Fan, Jing Zhang, Wei Ju, Benxue Liu, Xibin Yi
Abstract: The hierarchical of NiCo2O4@MnO2 core-shell nanotubes arrays anchored on 3D hierarchical porous carbon aerogels scaffold (NiCo2O4@MnO2-CAS) are prepared through a facile hydrothermal method combined with a simple thermal treatment. Such unique array nanoarchitectures and the synergistic effects of component nanomaterials exhibit remarkable electrochemical performance. The results show high specific capacitance of 786.0 F/g at current densities of 0.5 A/g, excellent rate performance and good cycling stability with capacitance retention of 84.9 % after 2000 cycles. An asymmetric supercapacitor with operating potential at 1.4 V is configured with NiCo2O4@MnO2 composites against active carbon, and exhibits a specific capacitance of 145 F/g at current density of 1 A/g and a high energy density of 39.0 Wh /kg at a power density of 350.0 W/kg.
Keywords: carbon aerogels; NiCo2O4@MnO2 composites; synergistic effect supercapacitors.
Scalable synthesis of Sn nanoparticles encapsulated in hierarchical porous carbon networks for high-rate reversible lithium storage
by Qingbin Zhu, Jinghao Liu, Yang Zhong, Guicun Li
Abstract: Sn nanoparticles encapsulated in hierarchical porous carbon networks (Sn@HPCNs) have been synthesized by the carbothermal reduction reaction of sodium stannate-crosslinked sodium polyacrylate xerogel. The synthetic strategy is simple and effective for the scalable production of Sn@HPCNs. The Sn@HPCNs show homogeneous distribution of Sn nanoparticles within hierarchical porous conductive carbon matrix. The obtained Sn@HPCNs exhibit high reversible discharge capacity (1652.1 mAh g1 at 0.1 A g1), superior rate performance (499.7 mAh g1 at 2 A g1), and excellent cycling stability (553.0 mA h g1 at 1.5 A g1 after 150 cycles). The superior lithium storage performances of the Sn@HPCNs are due to uniform distribution of Sn nanoparticles within hierarchical porous conductive carbon network, which could not only provide a conductive matrix, but also buffer huge volume change caused by lithiation and thus guarantee integrity of the Sn@HPCNs structure.
Keywords: Sn; Hierarchical porous conductive carbon network; Anode; Lithium ion batteries.
Silicon based anode materials with three-dimensional conductive network for high-performance lithium ion batteries
by Liekai Liu, Biaohui Huang, Pingjian Niu, Jingming Zheng, Ling Chai, Li Song, Hao Tang
Abstract: Silicon(Si) is expected to replace graphite as the next generation anode material for lithium-ion batteries(LIBs). However, Si has a low electron conductivity and large volume changing during the Lithiation/Delithiation process, which limits the commercialization of the Si anode. In this paper, micron whisker carbon nanotubes(MWCNTs) and graphene oxides(GO) were used to construct a three-dimensional conductive network to improve the electrochemical performance of the Si anode. Study found that GO and MWCNTs can greatly improve the performance of Si based anode. Among them, 5%GO/Si composite exhibited the highest charge capacity retention of 92.3%, maintains a capacity of 520.9mAh/g(contribution of micron Si is about 3388mAh/g) after 10 cycles.
Keywords: Keywords: lithium-ion battery; anode materials; three-dimensional conductive network; Si based anode.
Khaki-colored niobium oxide nanochains with enhanced lithium storage performances
by Yanxin Bian, Zhonghua Zhang, Jinfang Su, Changming Mao, Guicun Li
Abstract: Khaki-colored niobium oxides (H-Nb2O5) nanochains were synthesized via a facile low temperature solution-based method combined with hydrogenation treatment process. The nanosized chain-like architectures facilitate the fast lithium ion diffusions. Meanwhile, the hydrogen reduction process can effectively endow Nb2O5 with partial Nb4+ species and/or oxygen vacancies, resulting in a large enhancement of its intrinsic electronic conductivity. When evaluated for lithium storage capacity, the H-Nb2O5 showed twice the rate capability at 20 C compared to that of the pristine Nb2O5 nanochains due to the combination of the reduced path and Nb4+ doping induced high electronic conductivity. This facile hydrogenation method is promising for designing high performance carbon-free electrode materials for lithium ion batteries.
Keywords: Niobium oxide; Nanochains; Hydrogenation treatment; Anode; Lithium ion battery.
Influence of Shear-Induced Crystallization on the Rheological Behavior of Polyethylene
by Jinyan Wang, Xingyu Chen
Abstract: This paper presents a numerical simulation for the influence of shear-induced crystallization on the rheological behavior. The effect of flow on crystallization is considered through the mathematical relationship between the additional number of nuclei induced by shear treatment and the first normal stress difference. Avrami model is used to describe the crystallization kinetics. Normalized viscosity, orientation factor and extra stress are simulated with the development of crystallinity. It is found that the short-term shear treatment has a large effect on the crystallization dynamics of polyethylene , and a small amount of crystallinity causes a strong increase of shear viscosity. Beyond a specific shear strain the stress increases dramatically, which indicate the solidification of the material and the locking-in of stresses.
Keywords: Shear-induced crystallization; Crystallization kinetics; Rheological Behavior; Numerical simulation.
Surface modification of TiO2 Nanorod Arrays with Ag3PO4 @ PANI Nanoparticles for Enhancing Photoelectrochemical Performance
by Xiuquan Gu
Abstract: In this work, Ag3PO4@PANI particles with a core/shell structure were deposited onto the oriented TiO2 nanorod arrays (NRAs) by a facile dipping route, in order to enhance the visible-light response as well as photoelectrochemical (PEC) performance of TiO2 samples. Furthermore, the crystal structure, morphology, and optical properties of the composites (TiO2 photoanodes) were evaluated by a number of techniques, including scanning and transmission electron microscopy (SEM, TEM), X-ray diffractometry (XRD) and UV-vis spectroscopy. Meanwhile, on/off photocurrent response, and impedance spectroscopy measurements as well as Mott-Schottky analysis were employed to make a characterization over TiO2 photoanodes before and after surface modification. A photocurrent density of 4.0 mA cm-2 is achieved at 0.0 V vs. saturated calomel electrode (SCE) under an illumination of 100 mW/cm2, which is ~ 2 times higher than that of pristine TiO2 photoanode measured under the same conditions. The performance improvement was mainly attributed to the enhanced visible-light response of TiO2.
Keywords: Ag3PO4; photoelectrochemical; TiO2; nanorod array; Mott-Schottky.
Low temperature dependence of mechanical process of ultrathin aluminium films: molecular dynamics simulations
by Qiaoneng Guo, Jie-Fang Wang, Shi-E Yang, Mingxing Wang, Xue-Jie Han, Qiang Liu, Dong-Hui Zhu, Liang-Kui Hu
Abstract: The mechanical process of aluminium thin films under uniaxial tensile strain was simulated with molecular dynamics method in a low temperature range from 40 to 250 K. The stressstrain curve and potential energystrain curve of aluminium thin film under uniaxial tensile deformation were obtained by molecular dynamics simulations. The variation characteristics of stress-strain curves, with the changes of sample temperatures in uniaxial extension, are alike at the elastic stage in a temperature (T) range from 40 to 250 K. However, at the plastic stage the stress-strain curves are grouped into 3 categories (40K≤T<100K, 100K≤T<200K, 200K≤T≤250K) according to their variation characteristics. From the stressstrain curves, we gained the local maximum stress-temperature curve and its corresponding strain-temperature curve, and maximal potential energy-temperature curve and its corresponding strain-temperature curve. We found the strange temperature dependence of the local maximum stress, maximal potential energy and their corresponding strain: when the temperature is below 100 K, they go down quickly with temperature, and when above 100 K and below 200 K, they descend slowly and do very slowly above 200 K. By these dependences, we have identified two critical temperatures (100K and 200 K) for the transition of plastic flow mechanism.
Keywords: Thin film; Tensile properties; Temperature effect; Molecular dynamics.
Creating Binder-Free Supercapacitor Electrodes from Biomass Resources: A Nitrogen-Doped Pomelo Peel Derived Carbon Foam
by Hui Chen, Long Chen, Peirong Qi, Gang Wang, Lei Shi, Xiantao Feng, Feng Yu
Abstract: We conducted experiments in producing nitrogen-doped carbon foam using pomelo peels as a porous carbon material. Pomelos are a citrus fruit similar in appearance to grapefruit, and native to South and Southeast Asia. Specifically, we fabricated a nitrogen-doped pomelo peel derived carbon foam (N-PPCF) by using an ammonia gas treatment. The as-prepared N-PPCF had a high specific surface area of 1218.5 m2 g-1, an average pore size of 1.36 nm, and a pore volume value of 0.50 cm3 g-1. Additionally, the N-PPCF had a nitrogen content of 8.1 at%, allowing for a high specific capacitance of 150.1 F g-1 at a density of 1.0 A g-1. Even at 4 A g-1, the N-PPCF still maintained an ideal capacitance of 115.6 F g-1. Ultimately, we believe that N-PPCF is a potential method for treating pomelo peels, and that N-PPCF can function as a potential binder-free supercapacitor electrode.
Keywords: pomelo peel; carbon foam; biomass resources; agricultural waste; binder free; supercapacitor.
Sulfur-doped Banana Peel-Derived Activated Carbon as Electrode Materials for Supercapacitors
by Hui Chen, Zhuangzhi Zhao, Peirong Qi, Gang Wang, Lei Shi, Feng Yu
Abstract: Agricultural waste banana peel (BP) as a sustainable biomass resource is used to produce porous carbon (PC) and activated carbon (AC) materials. Sulfur-doped banana peel-derived AC (S-BP-AC) was successfully prepared for supercapacitors. The results show that the S-BP-AC presents a high Brunauer-Emmett-Teller surface area of 2224.9 m2/g, a large pore volume of 0.77 cm3/g, and a suitable pore-size distribution of approximately 0.8 nm. It is easy to bring S-BP-AC into contact with an electrolyte. The S-BP-AC electrode had great specific capacitance of 162.5 F/g at a current density of 0.5 A/g in a 6 M KOH aqueous electrolyte. The results indicate that the S-BP-AC can be applied to use in high performance supercapacitors.
Keywords: activated carbon; sulfur-doping; agricultural waste; banana peel; supercapacitors.
Enhanced Photocatalytic Activity of AgVO3/TiO2 Nanorod Array Composite Film under Visible Light Irradiation
by Tiantian Zhou, Shining Ni, Yundong Wu, Huaikai Li, Yongqiang Cao, Shengwen Fu
Abstract: The novel AgVO3/TiO2 nanorod array composite film (NACF) has been prepared by the hydrothermal and subsequent successive ionic layer adsorption methods. The photocatalytic films were characterized by the scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence (PL), and UV-vis diffuse reflectance spectra (UV-vis DRS). The SEM result showed that AgVO3/TiO2 NACF exhibited a well nanorod array structure, and some AgVO3 nanocrystals were deposited on the TiO2 nanorods. The novel AgVO3/TiO2 NACF showed the enhanced visible photocatalytic activity for degradation of methyl orange (MO) compared with the pure TiO2 nanorod array film. The deposition of AgVO3 nanocrystals on the TiO2 nanorod array led to the improved visible light absorption of the composite film due to the narrow bandgap of AgVO3 (less than 2.5 eV). The contact of AgVO3 and TiO2 resulted in the formation of semiconductor heterostructure, which led to the enhanced separation of photogenerated carriers. The improved visible absorption and efficient separation of photogenerated electron-hole pairs should result in the higher visible activity of composite film compared with pure TiO2 nanorod array film.
Keywords: TiO2 nanorod array; AgVO3; composite film; photocatalyst.
The Study on Flexible AgVO3 Nano Paper and its Visible Light Photocatalytic Activity
by Shining Ni, Yingzi Wang, Tiantian Zhou, Huaikai Li, Yundong Wu, Yongqiang Cao, Xuesen Qin
Abstract: By means of the facile hydrothermal method, the ultralong -AgVO3 nanobelts have been synthesized successfully. The properties of the as-prepared -AgVO3 nanobelts were investigated by the characterizations, such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-vis diffuse reflectance spectrum (UV-vis DRS). As shown by the SEM results, the obtained nanobelts showed a ultralong length of hundreds of micrometers and the width in the range of about 60 - 350 nm. The surface of nanobelt was also very smooth. XRD result exhibited that the AgVO3 nanobelts had a crystal phase. By the virtue of pumping filtration of AgVO3 nanobelts solution and corresponding post processing, the flexible AgVO3 nano paper was prepared successfully. The AgVO3 nano paper exhibited a well flexibility and photocatalytic activity determined by the degradation of rhodamine B (RhB) under the visible light (nm) irradiation. The possible mechanism for the photocatalytic degradation of RhB by AgVO3 was also proposed correspondingly. It is hoped that the synthesized flexible AgVO3 nano paper would also have the other applications in the fields, such as Li-ion battery, gas sensing, super capacitor, and so on.
Keywords: AgVO3 nanobelts; flexible; nano paper; photocatalyst.