bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructure of Silicon Nitride Fibers at Elevated Temperatures
Authors: Li Jun Zhe , Sun Xun , Liu Hai Tao , Cheng Hai Feng , Zhang Xiao Shan
Published: June 2017

The composition and microstructure of silicon nitride fibers after heat-treatment at elevated temperatures were investigated by XRD, NMR, XPS, SEM and TEM analyses. The results show that as-received fibers consisted of amorphous silicon nitride, and a little Si-C-O structure. During heat-treatment process, α-Si3N4 and β-Si3N4 formed resulting from the crystallization of amorphous silicon nitride, and the formation of β-SiC derived from the decomposition of Si-C-O structure. As heat-treated temperature increased from 1400oC to 1600oC, the above phenomenon become obvious, indicating that the fiber would possess high serving life with serving temperature lower than 1400oC. The tensile strength of fibers stays stable when heat-treated temperature was below 1200oC, while the strength retention of fibers sharply decreased to 50% after heat-treatment at 1400°C.
Combustion Synthesis: A Rapid Way for Preparing Bulk Cu2SnSe3 Thermoelectric Materials
Authors: Liu G.H. , Ma Rui , Li Jiang Tao , Li Yu Yang
Published: June 2017

The fabrication of bulk thermoelectric materials usually involves multi-step processes with considerable time and energy consumption. Here we applied a direct and rapid way of gas pressure assisted combustion synthesis to produce thermoelectric materials. As an example, bulk samples of Cu2SnSe3 had been prepared and their thermoelectric properties were investigated. Thermal analysis indicated that the Cu2SnSe3 samples kept stable up to 850 K. The un-doped Cu2SnSe3 showed ZT of 0.51 at 773 K, and by doping with Ag and In the ZT could be much increased to 1.42 at 823 K. The gas pressure assisted combustion synthesis method might provide a rapid way to directly produce bulk thermoelectric materials.
Complex Permittivity and Permeability Spectra of Nickel/Polyphenylene Sulfide Composite in Radio Frequency Range
Authors: Fan Guo Hua , Fan Run Hua , Wang Zhong Yang , Xie Pei Tao , Chen Min , Hou Chuan Xin , Ji Jian Chun
Published: June 2017

Due to the distinct electromagnetic properties, double negative materials have bright application prospect in many areas in the future. The nickel (Ni)/polyphenylene sulfide (PPS) composites were prepared by hot pressing Ni and PPS powders mixture. Microstructures, dielectric properties, and magnetic performances of the resulted composites were studied in detail. Once Ni contents exceeded the percolation threshold, the conductive networks would form and the conduction mechanism would change from hopping conduction to metal-like conduction. Due to the plasma oscillation of the free electrons within the conductive networks, negative permittivity appeared. Interestingly, circuit loops in the connected Ni particles induced by external electric field resulted in a diamagnetic phenomenon under high frequency for the composite with ferromagnetic Ni particles.
Structural, Electrical and Optical Properties of Ternary Al2xIn2(1-x)O3 Films Prepared by Metal Organic Chemical Vapor Deposition
Authors: Du Xue Jian , Feng Xian Jin , Wang Wei Guang , Luan Cai Na , Ma Jin
Published: June 2017

New wide band gap semiconductors with tunable properties are desperately needed to meet the ever-increasing demands of photoelectric devices operating in the ultraviolet (UV) or even deep ultraviolet (DUV) region. In this study, the ternary aluminum indium oxide (Al2xIn2(1-x)O3) films with different Al compositions of x [Al/(Al+In) atomic ratio] were successfully grown on the α-Al2O3 (0001) substrates at 650 °C by metal organic chemical vapor deposition (MOCVD). The influence of Al content on the structural, compositional, electrical and optical properties of the obtained films was investigated in detail. The structural transition from polycrystalline structure of bixbyite In2O3 to amorphous was observed as the Al content increased. The lowest resistivity of 1.52×10-3 Ω·cm was obtained for the sample with x=0.2, along with the respective hall mobility and carrier concentration values of 12.87 cm2V-1s-1 and 2.27×1020 cm-3. The average visible transmittances of over 83% were demonstrated for all the samples. The calculated values of optical band gap for the films indicated continuous increase from 3.82 to 5.88 eV as the x value increased from 0.1 to 0.9. The Al2xIn2(1-x)O3 films with tunable properties may be potentially employed in the fabrication of transparent optoelectronic devices, such as UV detectors, transparent TFTs and short wavelength light-emitting devices.
Stability of Sb2Te Crystalline Films for Phase Change Memory
Authors: Liu Guang Yu , Wu Liang Cai , Song Zhi Tang , Rao Feng , Song San Nian , Cheng Yan
Published: June 2017

Stability is one of the most important criterions to judge the quality of products, especially for the phase-change memory (PCM), which is regarded as the most promising candidate for next-generation non-volatile memory. Due to the lack of resistance stability, read errors can occur easily and the reliability of PCM will be influenced. Using Sb2Te as a base material, the resistance stability of Sb2Te was studied, and the results indicated that in the whole cooling process, the resistance of Sb2Te crystalline film was extremely steady under different annealing temperatures and different cooling rates. To unravel the reason why the resistance of Sb2Te crystalline film has good stability, further study was carried out and the results showed that there was no new diffraction peak in the XRD pattern, and the HRTEM images showed the similar hexagonal phase for the films under different annealing temperatures. Moreover, it was observed that the resistance in Sb2Te-based PCM device was still stable for crystalline state and amorphous state. These results revealed that the stability of Sb2Te crystalline films at a micro level and the stability of microscopic structure resulted in the stability of resistance. Therefore, based on the present study, the stability of phase-change material Sb2Te can be applied to exploit more reliable PCM for near-future application.
Structure and Electrochemical Performance of Melamine/Graphene Aerogel Composite for Supercapacitors
Authors: Wu Gao Li , Wu Li Li , Jin Jun Hong , Yang Sheng Lin , Li Guang
Published: June 2017

Melamine/graphene (GO/MF) aerogel composite was prepared through a simple one-step hydrothermal route, freeze-drying, and subsequent carbonization with graphene oxide (GO) and melamine resin. The structure, morphology and electrochemical performance of the composites were characterized by SEM, TEM, XRD-ray, Raman spectroscopy, and electrochemical tests. GO/MF aerogel possessed 3D porous structure and enlarged surface like aerogel materials for efficient ionic diffusion and transport. Melamine resin was used as N-doping agent, and the electrochemical performance of GO//MF was improved effectively. GO/MF aerogel shows a higher capacitance of 106 F/g at a current density of 0.1 A/g comparing to reduce graphen oxide (rGO). Not only the macroporous structure but also the N-doping agent had a significant impact on the capacitive behavior of graphene. These results provide a new method to prepare high performance electrode material as supercapacitors.
Investigation on NaCl Structure and Properties in External Electric Field
Authors: Lv Xin Yu , Wang Jun , Dong An Ping , Dai Yong Bing , Shu Da
Published: June 2017

Investigation on structure and electronic structure under external electric field is a very interesting subject. To investigate the evolution of structure and properties from the perspective of electronic structure, the configuration of NaCl crystal has been calculated with the first principles in different external electric field. The system of energy, bond length, geometrical, radial distribution function, difference charge density, and density of states has been carefully examined. The analysis of the calculated results suggested that, with the increasing of external electric field, the system energy presents the roughly increases to a maximum value then begin to decrease, the long range structure become more disordered, the geometrical structure is significantly influenced, the iconicity of NaCl enhances.
CO2 Emission Analysis of Light Aggregate Concrete Block in China
Authors: Sun Yan Qiong , Liu Yu , Cui Su Ping
Published: June 2017

The development and application of light aggregate concrete blocks are considered as one of the key issue that promote the energy saving and emission reduction in construction and building materials industries. In this paper, the greenhouse gas (GHG) emissions of light aggregate concrete blocks during the whole life cycle were analyzed based on life cycle assessment (LCA) methodology. The results demonstrated that the amount of GHG emissions of the light aggregate concrete block was 174 kg/m3 in the system boundary of ‘from cradle to gate’. The direct GHG emissions was 51.31 kg/m3 accounting for 28.46% of the aggregate emission, while the indirect GHG emissions was 124 kg/m3. The cement production and the concrete block production were the main contributors to the total emissions. According to the sensitivity analysis, the GHG emissions amount was quite sensitive to the amount of cement and ceramsite consumption.
Energy Consumption Analysis of Building with Typical External Thermal Insulation System
Authors: Li Yao , Gong Xian Zheng , Zhang Qing Hua , Shi Chong Qi
Published: June 2017

External wall thermal insulation system protects the major structure of building effectively. In this study, a student dormitory building with typical external wall thermal insulation system in Beijing was chosen as the research object and the energy consumption analysis was conducted to identify the optimal external thermal insulation system during the whole life cycle. The results show: for brick-concrete buildings, the consumption of clay brick, reinforced concrete and cement mortar account for more than 95% of the total materials consumption, where reinforced concrete contributes most to energy consumption. The external insulation system with similar heat transfer coefficient but consist of different insulation materials mainly affects energy consumption in materials production phase (the difference of building production energy consumption is about 7.2%), while has no significant effect in building operation phase and whole life cycle. With the increase of heat transfer coefficient, the energy consumption decreases in materials production phase, accounting for 16.3%-21.9% of the life cycle energy consumption, increases in building operation phase, accounting for 78.1%-83.7%, and can be neglected in the disposal phase. And there exists an optimization value in building whole life cycle, at which the minimum value of the energy consumption reaches, when the heat transfer coefficient is 0.3W / (m2 • K), equivalent to 127mm EPS insulation thickness or 151mm rock wool insulation thickness.
Effect and Mechanism of Sodium Fluosilicate on Setting Time of Cement
Authors: Wang Hai , Mao Qian Jin , Gao Yue , Wang Zi Ming , Cui Su Ping
Published: June 2017

Sodium fluosilicate (Na2SiF6) is prepared from by-product of phosphate fertilizer production. According to a certain percentage of Na2SiF6 mixed in the cement, the influence of different dosages on the setting time of cement under different water-cement ratio was discussed, and the effect of different forms of fluoride compounds on the setting time of cement were compared. The effect and mechanism of sodium fluosilicate on the hydration products of cement were researched by using the X-ray diffraction analysis and micro electron microscope. Experimental results show that the retarding effect of sodium fluosilicate on the coagulation time had a critical effect, and beyond a certain value, it sharply decreased the setting time. The critical dosage increased with the increase of water-cecment ratio. Compared with the retarding effect of Na2SiF6、MgSiF6、NaF and CaF2 on the coagulation time of cement, Na2SiF6 was the best. The incorporation of Na2SiF6 does not change the types of the hydration products, the main function of FN is hydrolyzed with Ca2+ ions to form CaF2 with a very low solubility.
Influence of Triethanolamine on Strength Development and Hydration of Cementitious Systems Blended with Titanium Slag
Authors: Liu Hui , Cui Su Ping , Wang Jian Feng , Yang Song Ge , Wang Xue Li , Liu Cong Wei
Published: June 2017

This paper investigates the influence of triethanolamine (TEA) on strength development and hydration of cement pastes and mortars incorporated with titanium slag (50% by mass of the total cementitious materials). The techniques including isothermal calorimetry, non-evaporative water content, and mercury intrusion porosimetry (MIP) were employed to characterize the hydration process at varied ages. The results show that: 1) 0.01%~0.10% addition of TEA has a positive effect on the strength development of blended cement mortars with titanium slag indicated by improved compressive strength and tensile strength; 2) TEA leads to an increase of hydration degree determined by measurement of isothermal calorimetry and non-evaporable water content before 28 d; 3) the cumulative porosity of cement pastes incorporated with titanium slag was reduced by TEA. Therefore, 0.01%~0.10% addition of TEA promotes the hydration of titanium slag, then forming more condensed structures, thus enhance the strength development of blended systems.
Ecological Design of New Type Aluminum-Plastic Composite Panel Based on LCA
Authors: Zhao Chun Zhi , Liu Yi , Jiang Quan , Ren Shi Wei
Published: June 2017

Aluminum-plastic composite panel is a kind of new type energy-saving and environmental-friendly curtain wall decorative material and is widely used in building exterior wall, curtain wall board, old building reconstruction and renovation and other projects. With the development and improvement of production and application technology, the performance and function of aluminum-plastic composite panel products are constantly optimized. Especially at the present, all countries in the world have increasingly strict requirements on fire safety, and the fire safety standards of buildings also have been improved continuously. Against this background, manufacturing enterprises have been actively developing new techniques and manufacturing new type aluminum-plastic composite panel, and have significantly improved the fireproof and flame-retardant properties of products on the basis of ensuring all the performance levels of products being acceptable. In this paper, the life cycle environmental impact of new type aluminum-plastic panels in three different ecological designs are compared based on life cycle assessment (LCA), and the suggestions on optimizing ecological design are proposed in combination with the performance indicator of aluminum-plastic composite panel, so it has important guiding significance for developing ecological design in industry of metal composite decorative panels.
Improvement of ADC12 Alloy by Optimizing CSP Process Parameters via Multiple Nonlinear Regression Analysis
Authors: Wang Ye , Niu Lian Jie , Wang Gang , Xu Hong Yu , Hu Mao Liang , Ji Ze Sheng
Published: June 2017

In order to improve the quality of ADC12 alloy billets prepared by Chips Solid Pressing (CSP) process, the effects of pressing temperature, pressure and packing time on the density of ADC12 alloy billets were investigated by using the orthogonal array and multiple nonlinear regression analysis. The results indicated that the pressing temperature has the greatest effect on the density of the billets, and it is followed by pressing pressure and packing time. The optimized process parameters, including a pressing temperature of 250oC, pressing pressure of 640MPa and packing time of 45 seconds, can be used to obtain the most compact billets of ADC12 alloy prepared by CSP process.
Effect of Testing Factors on Rietveld Quantitative Analysis of Cement-Matrix Materials
Authors: Gan Yan Ling , Cui Su Ping , Wang Ya Li , Guo Hong Xia
Published: June 2017

For cement-matrix materials, the microstructure plays a vital important role in the research. Recently, quantitative phase analysis of cementitious materials can be performed using the Rietveld method by fitting the calculated X-ray diffraction (XRD) profile with the observed one. The aim of this paper is to further perform the quantitative analysis by the Rietveld method and discuss the influence of testing factors on the Rietveld quantitative phase analysis. The factors included the collection range of pattern, step size and the scan time of per step. In this study, the chemical composition of the samples was determined by X-ray fluorescence (XRF) spectrometry. And their phase composition was calculated by X-ray powder diffraction and Rietveld analysis. The results showed that the collection range of pattern depended on the tested materials , and the scanning range should include the main diffraction peak of the sample. Smaller step size and longer scan time of each step made the fitting factor smaller, also the calculated pattern coincided with the measured pattern, better enhance the precision of the analyses.
Water Erosion Resistance Performance of the Pervious Recycled Concrete
Authors: Wang Yan , Li Chuan Jun , ZHANG A.Q. , Wang Xiao Long
Published: June 2017

According to the requirement of the special application environment of the pervious recycled concrete on water erosion and permeable ability, related performance affected by water has been studied and evaluated with scouring test method, using MTS810 and surface-dry permeability test. The experimental results showed that the anti-scour ability of recycled permeable concrete was relatively high. The mass loss in the scouring test was only 3.2% of the ordinary concrete under 10 Hz and 0.7 MPa loading conditions. Void ratio was larger than that of the target by the surface-dry permeability test, which fully met the requirements of the permeable concrete.
Solution Blow Spun High Performance Co-Polyimide Nanofibers
Authors: Li Jing , Yu Jun Rong , Zhu Jing , Wang Yan , Hu Zu Ming , Song Guo Cheng
Published: June 2017

Solution blow spinning (SBS) is an innovative nanofiber fabricating method with high productivity. 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) / p-phenylenediamine (PDA) / 4,4'-oxydianiline (ODA) co-polyimide nanofiber membrane was efficiently produced by SBS followed by imidization from precursor polyamic acid (PAA) nanofiber membrane in the paper. The morphologies and structures of the obtained PAA and PI nanofiber membrane were examined by SEM and FT-IR. The effect of thermal imidization temperature on the tensile property was investigated. The thermal stability of polyimide nanofiber membrane was also characterized by TGA.
Continuous Production of Hollow Hydrogel Fibers with Graphene Inner Wall
Authors: Hou Kai , Lin Yun Yin , Hsiao Benjamin S. , Zhu Mei Fang
Published: June 2017

Hydrogel fiber with spatiotemporal properties such as great aspect ratio, large surface area/volume ratio, orientation and knittability, has been considered as the potential application materials in the field of biomedicine area. On the basis of dynamic-crosslinking-spinning we reported before, a novel GO/PEG-PEGDA core-sheath hydrogel fiber was fabricated continuously. Moreover, uniform rGO-PEGDA hollow fiber was obtain after reduction process. The diameter of core and sheath can be controlled separately by adjusting extrusion rate of core solution and sheath solution, respectively. This novel series GO hybrid hydrogel fibers with core-shell or hollow structure have potential application on nerve and muscle tissue engineering.
Electroplating of Copper on the Continuous Carbon Fibers
Authors: Ni Jia Qi , Yu Mu Huo , Han Ke Qing
Published: June 2017

Surface metallization of continuous carbon fibers (CFs) can improve the properties of the interface between the CFs and the metal matrix of the metal based composites. In this study, copper was coated on the surface of continuous CFs by electroplating in acidified copper sulfate electrolyte system. The effects of electroplating parameters such as current density, plating time, plating temperature and the pH value of electrolyte solution on the electroplating of the copper thin films on CFs were studied. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to determine the microstructure of the copper coatings, and its composition and crystal structure. The thermal gravimetric analysis (TGA) was used to study the thermal stability of the CFs after electroplating. The results showed that high quality copper-coated CFs can be obtained under the optimized plating parameters as follows: the current density 3~4mA/cm2, electroplating time 10~20min, the temperature and the pH value of electrolyte solution 3.0~4.0, 20~30°C respectively. The coatings were uniform and smooth, which were adhered to CFs. XRD patterns indicated that the copper coatings were mainly composed of pure copper. And TGA results identified an increase in thermal stability of the copper coated CFs.
Crystallization Behavior of Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate) with WS2 as Nucleating Agent
Authors: Chen Zi Ye , Hu Ze Xu , Xiang Heng Xue , Chen Wei , Ni Zhang Gen , Zhu Mei Fang
Published: June 2017

Poly (3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) is one of the aliphatic polyesters that are completely synthesized by microorganisms. Owing to the physical and chemical properties of PHA being similar with those of polypropylene, PHBV is expected to be able to partially replace petroleum-based polymers, and to reduce the pollution of environment at the same time. However, many inherent defects, including slow crystallization rate, large-size spherulite and secondary crystallization phenomenon, restrict the development of PHBV. In the present study, PHBV/WS2 hybrid materials where the tungsten disulphide (WS2) acted as nucleating agent were produced, and then its accelerated crystallization effect on PHBV was evaluated. Mo’s methods were employed to describe the non-isothermal crystallization kinetics of the nucleated PHBV hybrid materials. The activation energy (ΔE) of hybrid material was calculated by Kissinger formula. It was found that the addition of low WS2 loadings strongly increased the crystallization rate of PHBV and correspondingly the crystallization half time (t1/2) decreased from 97s to 38s with only 1wt.% WS2 added. Meanwhile, the crystallization temperature (Tc) increased from 81.9°C to 112 °C. The results reported here are expected to be of great interest for the practical application of PHBV.
Fully Biodegradable Films Based on Functionalized Natural Polyphenol/Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate) as a Potential Material for Food Packaging
Authors: Xiang Heng Xue , Chen Zi Ye , Chen Wei , Zhou Zhe , Sun Bin , Zhu Mei Fang
Published: June 2017

As a potential material for food packaging, fully biodegradable composite films based on novel functionalized natural polyphenol/Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were successfully fabricated by solution casting, and also the functionalized natural polyphenol (C18TAx) was synthesized by grafting fatty acid onto natural polyphenol Tannic Acid (TA). The resultant C18TAx with better hydrophobicity was uniformly dispersed into a PHBV matrix. The influence of C18TAx dosage on the mechanical behavior, crystallization behavior and thermal properties of the C18TAx/PHBV composite films was investigated by uniaxial tensile mechanical testing, Differential Scanning Calorimeter (DSC), Polarizing Optical Microscope (POM) and Wide Angle X-ray Diffractometry (WAXD). The results revealed that the x value was about 0.09, showing that about 11/20 phenol hydroxy groups in TA molecules were replaced with fatty acid chains. Compared with those of neat PHBV, the tensile strength and elongation at break of the C18TA0.09/PHBV composite films with 10 wt.% C18TA0.09 content were enhanced by 121%, and 458%, respectively. This improvement was primarily ascribed to intermolecular hydrogen bonding interactions in composite films. This new type of fully biodegradable bio-based composite films shows great potential for food packaging.
Analysis of Twinning Behavior of Ti-2V Alloy Compressed at High Strain Rate
Authors: Wang Qiao Chu , Liu Rui , Ye Wen Jun , Yu Yang , Song Xiao Yun , Hui Song Xiao
Published: June 2017

The spilt Hopkinson pressure bar was employed to study dynamic compression mechanical response of Ti-2V alloy. The dynamic compression experiment was carried at a strain rate of 3000s-1. The microstructure of deformed specimen with ε=0.05, 0.18, 0.26 was observed by optical microscope. Electron Back-Scattered Diffraction (EBSD) technique was applied to confirm the types of twinning. Through analyzing mechanical response and microstructure evolution rule, the effect of element vanadium and deformation degree on dynamic mechanical properties and twinning deformation behavior was revealed. The results indicate that twinning is the prime dynamic deformation mechanism in Ti-2V alloy and the twinning fraction is increasingly raised during the deformation process. The twinning types, confirmed by Orientation Imaging Microscopy software, are namely {102}, {112} and {111} twinning. And the number of {111} twinning is far less than the other two types of twinning.
Preparation and Properties of Copolyesters Fiber with Flame Retardant and Anti-Droplet by In Situ Polymerization
Authors: Jiang Zhen Lin , Fang Shu Ying , Xu Hui Ling , Wang Chao Sheng , Ji Cheng Chang
Published: June 2017

Containing phosphorus compound is widely used in the modification of flame retardant polyester due to the excellent flame retardant properties. But it is difficult to solve the droplet problems, especially the polyester fiber. In this paper the copolyesters and fiber with flame retardant and anti-droplet were prepared using reaction containing phosphorus flame retardant [(6-Oxido-6H-dibenz [c, e] [1, 2] oxaphosphorin-6-yl) methyl] butanedioic acid (DDP) and silica sol by in-situ polymerization. The structure and properties of modification flame retardant were measured by nuclear magnetic resonance (NMR), thermal gravity analysis (TGA). The results indicated that the modification flame retardant was more suitable for polymerization. The TGA, limiting oxygen index (LOI), vertical flame test, and scanning electron microscope (SEM) were devoted to discuss the flame retardant properties. It suggested that the nanoSiO2 particles increased char residue, and the nanoSiO2 particles were conducive to the formation of dense stable carbon layer, inhibiting the expansion of the carbon layer to form holes, the nanoSiO2 particles improved the droplet of copolyester. The highest LOI of copolyester is 34.8±0.1%, the UL94 is V-0 grade. The copolyester fiber has excellent mechanical, flame retardant and anti-droplet. This can meet the requirement of household textile decoration and use.
Improvement of Mechanical Properties and In Vitro Degradation Resistance of Biodegradable Mg-1.5Zn-0.6Zr-0.2Sc Alloy by Extrusion
Authors: Li Tao , Zhang Hai Long , Tang Shou Qiu , Yang Yuan Sheng , Zhou Ji Xue , Wang Xi Tao
Published: June 2017

In the present study the extrusion process was performed on a novel biodegradable Mg-1.5Zn-0.6Zr-0.2Sc alloy, and the microstructure, mechanical properties, and in vitro degradation behavior of the alloy were investigated. The microstructure observation showed that the grain sizes were significantly refined after extrusion. However, there existed some long striped structures with relatively large grains along the extrusion direction. The strength, elongation, and hardness of the alloy were all improved after extrusion. The fracture mode transferred from quasi-cleavage fracture to ductile and cleavage mixed fracture. The strengthening mechanism belongs to grain refining strengthening. The cross section of the as-extruded Mg-1.5Zn-0.6Zr-0.2Sc alloy showed lower degradation rate and more uniform degradation mode compared with the longitudinal section. This can be explained by much refined grains, high microstructure uniformity, and low dislocation density.
Effects of External Heat Radiation on Combustion and Toxic Gas Release of Flame Retardant Cables
Authors: Zhang Jia Qing , Zhang Bo Si , Fan Ming Hao , Wang Liu Fang , Guo Xiang Jun , Yu Deng Yang
Published: June 2017

The effects of external heat radiation on combustion and toxic gas release characteristics of flame retardant cables, which were XLPE insulated, flame retardant PVC sheathed and steel armoured cables, were investigated. The combustion characteristics of the level A and the level C flame retardant cables were explored by the cone calorimeter. For the level C cables, heat release rate (HRR) and CO concentration in cable fires increased and the ignition time decreased with increase of the external radiation heat flux. For level A cables, the HRR and CO concentration showed two-stage variations with the external radiation heat flux. When the external radiation heat flux was smaller than 35 kW/m2, the cable self-extinguished quickly after the ignition. When the external radiation heat flux was larger than 50 kW/m2, the cables showed continuous burning phenomena after the ignition. The level A cable had smaller HRRs compared with that of the level C cable under the same external radiation heat flux. However, the CO concentration of level A cable was remarkably higher than that of the level C cable in the present study. The high CO release rate of cable with well flame retardant ability under large external radiation heat flux requires more caution in the cable fires.
Life Cycle Assessment of Cathode Copper Production
Authors: Li Hao , Gong Xian Zheng , Wang Zhi Hong , Li Yao
Published: June 2017

The environmental impact of Chinese cathode copper production was identified and quantified in the context of pyrometallurgy ical and hydrometallurgical method by life cycle approach. Combined with the situation of copper resources in China, the copper ores mining, mineral processing, transportation and smelting sector, were analyzed in detail. The normalization results shows that abiotic depletion is the largest environmental impact in both Pyro-and hydro-metallurgical methods, which were 28.4 kg Sb eq and 32.0 kg Sb eq, respectively. Electrolytic refining is the key process in hydrometallurgical life cycle environmental burden (50.21%), and the mining process contributed the largest environmental impact (17.94%) in pyrometallurgical process. In addition, the total environmental burden of pyrometallurgical process is 1.15 times of hydrometallurgical process. Pyrometallurgical methods has many environmental impact category which were much higher than hydrometallurgical because of the more use of fossil fuels in smelting process. Based on the life cycle assessment results, the key factors to reduce the overall environmental impact for China’s cathode copper production include optimizing the efficiency of copper resource, and clean energy sources for electricity production.
Substance Flow Analysis of Rare Earth Lanthanum in China
Authors: Chen Wen Juan , Wang Zhi Hong , Gong Xian Zheng , Sun Bo Xue , Liu Yu , Gao Feng , Nie Zuo-Ren
Published: June 2017

Substance flow analysis (SFA) is an established method to analyze the structure and characterization of resource flows or substance flows. Lanthanum (La) is an important type of light rare earth element, which is widely used in the fields of glass, luminescence, catalyst, agriculture, etc. This paper conducts a static SFA for lanthanum in China in 2002 and 2011, including different life cycle stages, e.g., exploitation, concentration, smelting, manufacture, use and disposal. Mining utilization efficiency, smelting ratio, export rate, ratio of scrap to raw material in 2002 and 2011 were comparatively analyzed. The results indicated that the utilization efficiency of La in the production stage of rare earth concentrates increased in 2011 relative to the value in 2002 by 80%, and the utilization efficiency of La in the manufacturing stage increased by 74%. The results also showed that although the mining utilization rate was increased, the resource efficiency was still low and how to increase the resource efficiency is a significant issue for Chinese rare earth industry. On the based of the results, some advices were also proposed, which will provide useful reference information for the green development of Chinese rare earth industry.
Thermal Decomposition Characteristics and Drying Process of Municipal Sludge
Authors: Zhao Qi Gang , Wang Ya Li , Nie Zuo-Ren , Liu Hong , Cui Su Ping
Published: June 2017

Using cement kiln dispose sludge from sewage plants can achieve the sludge stabilization, harmless, reduction and resource comprehensive utilization purposes. This is Not only to solve the problem of sludge treatment which is difficult to solve by sewage treatment plant, but also to make full use of the sewage treatment plant sludge to replace part of cement clinker production materials. And it makes full use of sludge incineration emitted in the process of low calorific value. Municipal sludge contains more moisture. It is necessary to dry the sludge outside the kiln before entering kiln process. As cement kiln co-processing, it should be combined with the characteristics of NSP clinker production, it is necessary to not only consider the total energy consumption of the drying process, but also the re-use of dried sludge heat value, as well as consider the total of water into the kiln by drying sludge affecting the whole clinker production process. In this paper, with the initial solid content 20%, dry heating value 3400 cal/g sludge as a research object, the moisture morphology, thermal characteristics, drying technological parameters and composition of water after drying in sludge were analysed. This issue combines sludge drying with cement kiln disposal, which can not only solve the heat and odor problem during the individual sludge drying process, but also provide a theoretical basis for cement kilns co-disposal of municipal sewage sludge to achieve the purposes of sludge stabilization, harmless, minimization and resource utilization.
Effects of A-EMS on Microstructure and Mechanical Properties of DC Casting Al-10Si-1.1Ni Alloy
Authors: Qiu Yang , Zhang Zhi Feng , Gao Ming Wei , Luo Ya Jun , Gai Hong Tao
Published: June 2017

Al-Si alloys were characterized by excellent corrosion and wear resistance, low thermal expansion and high specific strength. Adding Ni to Al-Si alloy contributes to enhance the elevated temperature strength. However, the coarse structures and Ni-containing phases are disadvantageous for the mechanical properties. In this paper, an advanced melt treatment technology named the annular electromagnetic stirring (A-EMS) process was utilized for the Al-10Si-1.1Ni alloy to examine the effects of A-EMS on structures and mechanical properties. Research results showed that in the case of A-EMS, the billets with finer solidification structures and Ni-containing phases morphology as well as higher performance were achieved.
Microstructure and Creep Behaviors of As-Cast Mg-Zn-Er Alloys
Authors: Li Rui Jing , Li Shu Bo , Liu Ke , Wang Zhao Hui , Du Xian , Du Wen Bo
Published: June 2017

The microstructure and creep behaviors of cast Mg-xZn-yEr (x=3,6,9 wt.%, x/y=6) alloys were investigated by X-ray diffraction (XRD), optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). XRD results indicated that the main phase compositions of as-cast Mg-xZn-yEr alloys were the icosahedral quasicrystalline phase (I-phase) and α-Mg solid solution. The I-phase mainly distributed in the dendritic and staccato strips. The creep tests were conducted under the condition of 448 K, 70 MPa for 100 h. As the addition of Er increased from 0.5 wt.% to 1.5 wt.%, the total creep strain decreased from 0.962% to 0.512%, and the steady state creep rate decreased from 1.411×10-8s-1 to 4.917×10-9s-1. The I-phase had a tendency to be bulky and continuous, as the volume fraction of Er element increased. Ascribed to the I-phase, the creep strain happened and effectively blocked the movement of dislocations, resulting in the strengthened as-cast Mg-Zn-Er alloys and improved creep resistance. Based on the investigation of creep behaviors, the creep mechanism of the as-cast alloy was mainly grain boundary slipping.
Properties of Argon Gas Atomized Ti-43Al-9V-Y Alloy Powders
Authors: Liu Yu Feng , Liu Na , Li Zhou , Zheng Liang , Xu Wen Yong
Published: June 2017

The properties of Ti-43Al-9V-Y alloy powders, which were produced by cold crucible melting and argon gas atomization, were investigated. The results showed that the size of the powders was normal distribution in a range of 10-210μm. The powders possessed a near perfectly spherical shape. The microstructure of the powders was composed of dendritic and cellular crystal grains, and the dendritic crystal grains decreased in finer particles. The X-ray diffraction result indicated that there were two main phases, α2 and B2 in the powders, and the amount of B2 phase increased as the particle size decreased. In addition, the oxygen and nitrogen contents were below 1000ppm and around 140ppm, respectively.
Microstructure and Properties of Al-Cu-Mn Alloy with Y, Zr and (Y+Zr)
Authors: Guo Ting Biao , Zhang Feng , Li Qi , Wang Chen , Ding Wan Wu
Published: June 2017

As an important strengthening method, micro alloying has been widely used to improve the comprehensive properties of aluminum alloy. The research on microstructures and properties of Al-Cu-Mn alloy with Y, Zr and (Y, Zr) was conducted through OM, SEM and EDS methods. Three addition methods were comprehensively compared and the important significance of elements and relevant precipitates distribution to performance improvement was explored. The results show that adding different contents of Y, Zr and (Y, Zr) has great influence on microstructure and properties of Al-Cu-Mn alloy. Fluidity of the (Y+Zr)-containing alloy was significantly higher than that of the Zr or Y-containing one. The hardness and elongation of the Zr-containing alloy were also better than the other two groups, while with the increase of addition amounts from 0 to 0.2 %, it showed a decreasing trend. When the content was 0.3%, the grains of the Y and (Y+Zr)-containing alloys were well refined and the tensile strength and hardness increased as well, and Y-containing alloy presented the best tensile strength. After T6 heat treatment, the mechanical properties of the Y and (Zr+Y)-containing alloys were enhanced due to the dispersed θ phase and completely refined grains. And both ductile fracture ratios increased. When the content was more than 0.3%, the reticular θ phase formed that was extremely unfavorable to properties of the studied alloy. It appears that the addition of Y and Zr has an important influence on improving the properties of the Al-Cu-Mn alloy. And Y, Zr and (Y+Zr) dosages should be adjusted reasonably in the range of 0.1-0.3% to optimize and improve the alloy performance.
Constitutive Equations for 6061 Aluminum Alloy at Elevated Temperature
Authors: Shen Zhi
Published: June 2017

Isothermal compression tests were conducted on 6061 aluminum alloy using a Gleeble-3500 thermal simulator under constant strain rates and at deformation temperatures ranging from 623 to 773K, up to a 60% height reduction of the sample. The high temperature deformation behavior of 6061 aluminum alloy was characterized based on an analysis of the stress-strain curves. A set of constitutive equations for 6061 aluminum alloy were proposed by employing an Arrhenius-type equation. Material constants, A, n and activation energy Q were found to be functions of strain. The equations revealed the dependence of flow stress on strain, strain rate and temperature. In order to evaluate the accuracy of the deformation constitutive equations, the mean errors of flow stress between the experimental data and predicted results were plotted. The results showed that the predicted data agreed well with the experimental stress-strain curves.
Effect of Hot Isostatic Pressing on Microstructures and Mechanical Properties of IN738LC Superalloy
Authors: He Qun Gong , Liu Jun , Li Lin Xu , Gao Zhen Huan , Shi Xiao Yan , Yang Gong Xian
Published: June 2017

The microstructures and mechanical properties of IN738LC superalloy made by investment castings followed by Hot Isostatic Pressing (HIP) treatment have been investigated. The results revealed that after HIP treatment, the microporosities have been almost removed and the density rose by 0.21%. The eutectic size became smaller and the fraction decreased. The γ' phase was more regular and also increased in size, while a large number of secondary γ' phase appeared. With HIP treatment, the impact toughness increased from 5.0J ~ 7.0J to 8J ~ 9J and tensile strength at 200°C ~ 800°C was improved by approximately 3.2%~19.7%. In addition, the ductility and the stress rupture life have also been greatly improved as well.
Effect of a High Magnetic Field on the Microstructure of Directionally Solidified NiAl-Cr(Mo)-Si Near-Eutectic Alloy at Different Withdrawal Rates
Authors: Liu Huan , Xuan Wei Dong , Ren Xing Fu , Wang Bao Jun , Yu Jian Bo , Ren Zhong Ming
Published: June 2017

The effect of a 6T high magnetic field on the microstructure of directionally solidified NiAl-Cr (Mo)-Si near-eutectic alloy was investigated at the withdrawal rates of 2, 10 and 50 μm/s. The results showed that the microstructure evolved from planar eutectic to primary NiAl dendrites + cellular eutectic and then to dendritic eutectic with the increasing withdrawal rate. When the magnetic field was imposed, the well-aligned eutectic lamellae were disturbed and transformed into a wavy one at 2 μm/s. When the withdrawal rate increased to 10 μm/s, the application of the magnetic field destroyed the primary NiAl dendrite array and caused the occurrence of columnar-to-equiaxed transition (CET) of the NiAl dendrites. The volume fraction of primary dendrites also decreased. In addition, the width of intercellular/interdendritic regions decreased in cellular/dendritic eutectic structures when directionally solidified under the magnetic field. The above results should be attributed to the combined action of the thermoelectric magnetic force and the thermoelectric magnetic convection.
Microstructures of Low Angle Boundaries of a Third Generation Single Crystal Superalloy DD9
Authors: Yang Wan Peng , Li Jia Rong , Liu Shi Zhong , Zhao Jin Qian , Shi Zhen Xue , Wang Xiao Guang
Published: June 2017

The microstructures of low angle boundaries (LABs) of a third generation single crystal superalloy DD9 in as-cast state and after different heat treatment processes were studied by optical microscopy (OM) and field emission scanning electron microscopy (FESEM). The results showed that the as-cast LABs of DD9 alloy consisted of rod-like and bulk γ' phases with γ matrix between them, and there were eutectic γ-γ' precipitating at the LABs, as well as small amounts of discrete distribution of carbides. The γ' phase locateed at the grain boundaries was larger than that distributed on both sides of the grain boundaries. After the solution heat treatment, as-cast eutectic γ-γ' at LABs dissolved completely, and rod-like γ' phase was still found at some LABs. Meanwhile, the LABs were inclined to be straight compared to the as-cast state. The primary aging heat treatment made γ' phase at the LABs dissolved completely, and the secondary aging heat treatment resulted little change in the morphology of the LABs. Thus, the effect of the primary aging heat treatment on the microstructures of the LABs was greater than that of the secondary aging heat treatment.
High Temperature Rupture Life of Nickel-Based Superalloy under Directional Solidification with High Temperature Gradient
Authors: Zhang Wei Guo , Liu Zhi Jie , Feng Song Ke , Yang Fu Zeng , Liu Lin
Published: June 2017

The stress rupture life of DZ125 nickel-based superalloy that was prepared by directional solidification process under the temperature gradient of 500 K/cm has been studied at 900°C and 235MPa. The results showed that with the increase of directional solidification rate from 50 μm/s to 800 μm/s, the primary dendrite arm spacing reduced from 94 μm to 35.8 μm and γ' precipitates reduced and more uniformed in size. The high temperature stress rupture life of as-cast sample increased firstly and then decreased and reached its maximum at the solidification rate of 500 μm/s. The dislocation configuration of sample with refine dendritic structure after stress rupture was investigated and discovered that the dislocations in different parts of sample had different morphology and density, which indicated that the deformation of as-cast samples were uneven during high temperature stress rupture. A lot of dislocations intertwined around carbides and at the interface of γ/γ', and the dislocation networks were destroyed and the dislocations entered γ' precipitate by the way of cutting.
Effect of Solution Treatment Temperature on the Grain Growth Behavior of Fine Grained FGH96 Superalloy
Authors: Feng Ye Fei , Zhou Xiao Ming , Zou Jin Wen , Wang Xiao Feng , Tian Gao Feng , Wang Wu Xiang
Published: June 2017

The effect of solution treatment temperature on the grain growth behavior of fine grained nickel-base superalloy FGH96 has been investigated. The results showed that with the increase of solution treatment temperature, the grain growth of fine grained FGH96 alloy (<5μm) experienced 3 stages, the slow growth stage below 1120°C, the steady grain size stage from 1120°Cto 1250°C, which revealed the fine grained FGH96 alloy with wide solution treatment window compared to coarse grain, and the exponential growth stage. At the same time, the primary γ′ and MC carbides on impeding grain boundary migration to limit grain growth was demonstrated. The grain growth model has been established, and the activation energy of grain growth was calculated to be 288 KJ/mol through linear fitting.
Oxidation Behavior of a Disk Powder Metallurgy Superalloy
Authors: Dong Kai Xin , Yuan Chao , Gao Shuang , Guo Jian Ting
Published: June 2017

Oxidation behaviors of a spray-forming disk superalloy LSHR were investigated in the temperature range of 750-900°C. The composition and morphology of oxidation scales were investigated by X-ray diffraction (XRD), scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS), and electron probe microanalysis (EPMA). Oxidation kinetics was studied by the means of isothermal oxidation testing in air and weight gain measurement. The oxide scales were composed of Cr2O3, TiO2, Al2O3 and a small amount of NiCr2O4. The experiment results showed that oxidation kinetics and oxide layers followed a square power law as time extended from 750 to 900°C. With the oxidation temperature increasing, external scale thickness, and internal oxidation zone increased. The oxidation behavior was controlled by the diffusion of oxygen, chromium, titanium, and aluminum ions, as chromium, titanium, and aluminum ions diffused outward and oxygen diffused inward. Based on the standard HB5258-2000 spray-forming LSHR exhibited an excellent oxidation resistance in the whole test temperature range.