bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Doping Concentrations on Properties of Nb Doped ZnO (NZO) Ceramics Targets
Authors: Peng Wei , Xu Ting Ting , Zhu Zuo Xiang , Shang Fu Liang , Xie Sheng Hui , Gao Ling , Yang Hai Tao
Published: June 2017

Nb doped ZnO (NZO) ceramic targets were prepared by sintering in air for 3 hours. The morphologies, structure, densification behavior, mechanical and electrical properties of the sintered ceramic targets with different doping concentrations were investigated. The optimal doping concentration was obtained. The results indicated that the sintered NZO ceramic targets with doping amount of 1wt.% (1wt% Nb2O5) had optimum comprehensive properties, which was corresponding to an electrical resistivity of 1.87×10-2Ω·cm, a relative density of 99.1%, a Vickers hardness of 320MPa and a bending strength of 72.8MPa. The NZO ceramic target has a potential to be used as a high-quality sputtering target to deposit ZnO-based transparent conductive films.
Growth of Single-Crystalline Tris-(8-Hydroxyquinoline) Gallium Uniform Sub-Microrods and their Optical Properties
Authors: Dai Cheng Hu , Wei Zhi Xian , Pang Zhi Yong , Han Sheng Hao
Published: June 2017

One dimensional (1-D) organic materials have a bright prospect in the field of optoelectronics. Intrigued by these, 1-D uniform sub-micrometer tris-(8-hydroxyquinoline) gallium (GaQ3) rods were prepared with surfactant by an extremely facial method. The GaQ3 rods with hexagonal cross sections had excellent crystallinity and optical properties. The measurement of the absorption spectrum showed that there was an obvious blue shift comparing with the GaQ3 film. This can be explained by that the molecular packing in the α-phase rods has a looser interligand spacing compared with the GaQ3 film, consequently resulting in reduced orbital overlap and larger energy gap.
Synthesis and Fluorescence Properties of a Terbium Complex with Ferrocenylazobenzoic Acid in Nanoparticles
Authors: Lv Yu Guang , Wang Bo , Qin Yu Shan , Qi Xiao Li , Song Shan Shan , Song Di
Published: June 2017

Tb (AUFA)32H2O, a rare earth terbium complex,was synthesized by introducing 4-(11-azobenzene-undecyloxy) ferrocene acid (AUFA) as the ligand. This complex was characterized by elemental analysis, MS, IR, Raman, UV spectroscopy and fluorescence spectrophotometry. The complex exhibited ligand-sensitized green emission, and Tb (AUFA)32H2O had a higher sensitized luminescence efficiency and a longer lifetime than the other terbium complexes (DPC: 2, 6-Pyridinedicarboxylic acid, Aspirin: 2-ethanoylhydroxybenzoic acid). The organic-inorganic thin film of complexe Tb (AUFA)32H2O in nanoTiO2 was fabricated, and the nanoTiO2 has been used in the luminescence layer to change the luminescence property of complexes Tb (AUFA)32H2O. It was found that there was an efficient energy transfer process between the ligands and metal ions. Moreover, In an ITO/PVK/Tb (AUFA)32H2O/Al device, Tb3+ may be excited by intramolecular energy transfer from the ligand, as observed by electroluminescence. The main emitting peak at 545 nm can be attributed to the 5D4→7F5 transition of the Tb3+ ion, and this process results in the enhancement of the green emission from the electroluminescence device.
A Novel Way to Modify PTFE Membrane into Hydrophilicity
Authors: Liu Shi Jie , Cui Su Ping , Qin Zhen Ping , Fei Chua Jun , Wang Ya Li , Guo Hong Xia
Published: June 2017

Polytetrafluoroethylene (PTFE) membrane, with high resistances to acid, alkali and other chemical corrosion, is the ideal filter material in water treatment, which can be used in a variety of harsh environment. However, the hydrophobictity of PTFE membrane limits its wide application in water treatment. Thus, the hydrophilic modification of PTFE membrane attracts much attention. In this work, the microporous PTFE membrane was treated by a novel strategy for enhancing its hydrophilicity. The pristine microporous PTFE membrane was modified by assembly of fluorocarbon surfactant. The structure and morphology of the membranes were characterized by attenuated Fourier Transform Infrared spectroscopy (ATR-FTIR) and scanning electron microscope (SEM). The variation of wettability was evaluated by the change of water contact angle (WCA). And the influences of the concentration of fluorocarbon surfactant and modification time on PTFE WCA were also investigated as well. The WCA of the pristine PTFE membrane is 156°. After modified by 5.0 g/L of fluorocarbon surfactants, the WCA reduced to 4.3°, indicating that the hydrophobic PTFE membrane was transformed into a hydrophilic one. FTIR and SEM results indicated that there were hydrophilic groups, such as carbonyl (-C=O) and hydroxyl (–OH) existing on the surface of PTFE membrane after modification. And WCA of the hydrophilic membrane showed a slight increase from 4.3°to 8° after a week, indicating that the hydrophilic PTFE membrane exhibiting a persistent durability.
Effect of Sintering Temperature on the Structure and Properties of Attapulgite-Based Nanofibrous Membranes
Authors: Zhu Ye Kai , Chen Da Jun
Published: June 2017

Attapulgite (AT)-based nanofibrous membranes (NFMs) were fabricated via a facile papermaking procedure, and the AT-based NFMs were sintered at three different temperatures (240 °C, 400 °C, and 600 °C). The effect of sintering temperature on the structure and properties, such as specific surface area, pore size distribution, porosity, mechanical property, pure water fluxes of AT-based NFMs, were investigated. The results showed that average pore size, total pore volume, and porosity of AT-based NFMs increased with increasing of the sintering temperature, while specific surface area and flexural strength of AT-based NFMs decreased. The optimal sintering temperature for AT-based NFMs was 400 °C. In addition, it was also found that the swelling degree of AT-based NFMs in aqueous solutions was suppressed and the pure water fluxes of AT-based NFMs were improved by sintering process.
Sensing Mechanism of SnO2 (110) Surface to NO2: Density Functional Theory Calculations
Authors: Wang Xiaofeng , Ma Wei , Sun Kai Ming , Hu Ji Fan , Qin Hong Wei
Published: June 2017

It is necessary to develop NO2 gas sensors as NO2 is a pollutant. While, different from the reducing gases, oxidizing gas NO2 will put up a complicated sensing process. Density functional theory (DFT) calculations are necessary to be performed to understand NO2-sensing mechanisms at the atomic level. In this study we introduce NO2 to SnO2 (110) surface with oxygen species pre-adsorbed. The results show that NO2 sensing mechanism of SnO2 surface strongly depends on the concentration of oxygen in the ambient atmosphere (usually, no effects of temperature and pressure are considered). The direct interactions between NO2 molecule and SnO2 sub-reduced surface (with two rows of fold-coordinated bridging oxygens removed) for very low oxygen concentrations show that, NO2 gas molecules interact directly with Sn instead of reacting with oxygen species, resulting in an increase in resistance of SnO2. We investigate gas-sensing processes of interaction between NO2 molecule and SnO2 surface with pre-adsorbed oxygen species for the case of considerable high oxygen concentrations. Adsorbed molecular oxygen ions compete with adsorbing NO2 molecules for available surface sites and electrons from the SnO2. As the availability of oxygen ions on the SnO2 surface increasing, the interaction between NO2 and adsorbed oxygen species give rise to a reducing interaction, which brings a decrease in resistance of SnO2.
Hardening Performance and Mechanism of Fluosilicate Surface Treatment Agent on Cement-Based Materials
Authors: Liu Xiao , Guan Jia Nan , Zheng Yun Sheng , Wang Zi Ming , Shen He Qing , Ren Xiao Wei
Published: June 2017

Based on the theory of ecological resources recycling, the effects of matrix quality, surface treatment method, soaking time, age after treatment and fluosilicate cation on hardening cement based materials were investigated by using the byproduct of phosphate fertilizer production namely fluosilicate as the surface treatment agent of cement-based materials and changing different surface treatments. The results showed that the permeation capacity of surface hardener solution , the wear resistance and surface hardness of cement-based materials were significantly improved by the treatments of surface sanding and oven drying. Both surface spraying and submerging methods can promptly increase the hardening effect by more than 20%, manifesting as the rapid improvement of wear resistance in 1 day and the maintenance of that in 7 days. The effective spraying amount and soaking time were 100g/m2-200g/m2 and 6 h, respectively. The fluosilicate surface hardener exhibited better hardening effect than the silicate surface hardener for those matrix materials with different quality, especially for the matrix materials with low compactness. The magnesium fluosilicate displayed the best hardening effect. Besides, the mechanism of fluosilicate and silicate surface hardeners were discussed and compared. The results show that the fluosilicate surface hardener produced crystals and colloids by reacting with cement hydrates to fill the void and improve the compactness, other than the silicate surface hardener which produced calcium silicates by reacting with cement hydrates. As a result, the hardness and wear resistance of cement-based materials are improved, but also the probability of a potential alkali-aggregate reaction is substantially reduced.
Influence of Triethanolamine on the Properties of Cement-Based Materials
Authors: Wang Xiao Ying , Lan Ming Zhang , Hou Wei Fang , Xiang Bin Feng , Zhao Xu Dong
Published: June 2017

The effects of triethanolamine on the compressive strength and setting time of fly ash cementitious materials, slag cementitious materials, and limestone cementitious materials were investigated. The results show that the dosage of 0.04% of triethanolamine can significantly improve the 3d, 7d and 28d compressive strength of fly ash cementitious materials. It possesses less impact on the setting time. The dosage of 0.04% of triethanolamine can significantly improve the 3d and 7d compressive strength of slag cementitious materials while the effect of late strength is not obvious. It extends the initial setting time and the final setting time is not changed, which has retarding effect. The results of hydration heat and XRD show that triethanolamine extends the induction period of cement hydration, and gypsum is exhausted in advance during the hydration process. Triethanolamine promotes the transformation of AFt to AFm and there is no effect on the type of hydration products.
Structure and Compressive Property of Heterocyclic Aramid Fiber
Authors: Song Ying Deng , Li Bin Tai , Xing Li Ying
Published: June 2017

The F-3 fiber is a trade name of a recently developed type of heterocyclic para-aramid fibers in China. To investigate the relationship between structure and compressive properties for F-3 fiber, the structural parameters and compressive strength have been analyzed in detail compared with the Kevlar-49 fiber. The structural parameters were determined by wide-angle X-ray diffraction (WAXD) analysis and sonic velocity method. The results showed that the orientation of chains of F-3 fiber was higher than that of Kevlar-49 fiber. The results of the tensile recoil method showed that F-3 and Kevlar-49 fibers had approximate compressive strength. The analysis of relation between structure and mechanical properties suggested that the combination of orientation parameter and shear modulus between adjacent chains resulted in the approximate compressive strength of F-3 and Kevlar-49 fibers.
Copolymerization Modification of PPTA with 2,5-Furandicarboxylic Acid: Towards High-Performance Material with Enhanced Solubility
Authors: Luo Kai Ju , Wang Yan , Yu Jun Rong , Zhu Jing , Hu Zu Ming
Published: June 2017

The preparation and characterizations of soluble copolymers poly (p-phenylene terephthamide-co-furandicarboxylic p-Phenylenediamine)(PPTA-co-PPF) by direct polycondensation was described. The chemical structure of polyamides was investigated by 1H NMR and FT-IR. The good solubility of copolymers in organic solvents was certified at room temperature. Their thermal stability and mechanical properties were observed by TGA and tensile testing and then compared with that of traditional high performance aromatic polyamides (PPTA and PMIA, for example, with trademarks of Kevlar® and Nomex®). The furan ring incorporated polyamide was expected to form thermal reversible cross-linked polymer network through D-A reaction.
Photo-Induced Charge Generation of TiO2 Nanotube Modified with Polymer Containing C60 under Irradiation of Visible Light and its Applications
Authors: He Xiao Chun , Wang Meng , Qiu Jian Xun , Zhang Xin Tao , Gao Ming Jun , Lv Shi Sheng , Ma Xing Fa , Li Guang
Published: June 2017

Due to its excellent physical properties and inert chemical reaction activity of C60, it is possible to synthesize solution-processing polymer containing C60 utilizing the inclusive characteristics of polymer chain segment, and then to prepare organic/inorganic nanocomposites with enhanced some key properties. In order to harvest the visible light of TiO2 effectively the surface modification of TiO2 nanotube with polymer containing C60 was carried out in this study. A series of characterizations were performed by SEM (scanning electron microscopy), TEM (transmission electron microscopy), Fourier-Transform Infrared (FTIR) spectra, UV-Vis (Ultra-violet visible spectroscopy), XRD patterns analysis. The results showed that the UV-Vis of resulting nanocomposite was almost covered the whole region of visible light. The photoconductivity response to visible light with low-power were studied based on interdigital electrodes of Au on flexible PET (polyethylene terephthalate) film substrate with casting method. The results indicated that the photoresponses of two kinds of polymer containing C60 to weak visible light emerged photo-switching behavior, its recoverability was also rapidly, and the photoresponse of TiO2 nanotube modified with two kinds of polymer containing C60 to weak visible light also changed greatly. This illustrated that the organic-inorganic nanocomposites showed good activities to weak visible light. Photocatalytic efficiency was examined by selecting typical organic pollutants, some good results were obtained. It may develop organic-inorganic nanocomposites with external stimuli response, photocatalyst, et al.
Preparation of Nano Cu-ZnO/PET Fiber for Antibacterial Application
Authors: Jin Jin , Fang Ling Jie , Tang Lian , Ji Peng , Wang Chao Sheng , Wang Hua Ping
Published: June 2017

Polyethylene terephthalate (PET) fiber is applied to clothing, home textiles and other fields because of its low cost, high strength, quick-drying and stable structure, etc. Polyester fiber generally doesn’t have the ability to kill bacteria, and it is a kind of porous material which is conducive to the microbial adhesion and spread of bacteria. In the present study, Cu-ZnO and its antibacterial PET fibers were prepared by sol–gel method and melt spinning, respectively. The structures and compositions of Cu-ZnO were characterized by X-ray diffraction (XRD) and Fourier transform-infrared (FT-IR) spectra. The crystallization and melting behavior of the PET/Cu-ZnO (0.05:1) composites were tested by differential scanning calorimetry (DSC) to determine the temperate of melt spinning. The morphologies and mechanical properties of antibacterial polyester fiber were studied by field emission scanning electron micrographs (FE-SEM) and strength machine, respectively. The antibacterial properties of the samples on E. coli and S. aureus were determined using powder inhibition zones and antibacterial rate. The results show that the fibers exhibited excellent antibacterial activity, it had obvious inhibiting effects on E. coli and S. aureus and the antibacterial rate were both above 90%.
Effect of Different Factors on the Fibrillation Degree of Lyocell Fiber Based on Homogenization Treatment
Authors: Li Qiao , Jiang Chen , Yang Ge Sheng , Zhang Hui Hui , Yu Min Min , Shao Hui Li
Published: June 2017

The homogenization treatment was performed to fibrillate Lyocell fiber, and then the effects of different factors including NaOH concentration, homogeneous time, temperature and bath ratio on the fibrillation degree of Lyocell fiber were investigated through the orthogonal experiment. Various characterization techniques were employed to compare the fibrillation degree of Lyocell fiber. The polarized light microscope (POM) and scanning electron microscope (SEM) were used to observe the appearance of the fiber after different treatment, and the results showed that it was a quick and efficient approach to obtain the fibrillated Lyocell fiber by homogenization treatment, and the fibrillation degree of fibers varied with different treatment conditions. The results of water retention value (WRV) and the characteristic parameter of the fibrillation degree revealed that the ranking of factors affecting the fibrillation degree of fibers was NaOH concentration > homogeneous time > temperature > bath ratio, using the extreme difference analysis and variance analysis methods. The degree of fibrillation was influenced dominantly by NaOH concentration, rather than any other three factors. By means of BET test, the specific surface area of treated fiber showed a similar trend with WRV, and they matched well with fibril amount on the fibers observed by SEM.
Functionalization of α-ZrP by 1,2-Epoxypropane for Further Modification
Authors: Hossamaldin Ahmed , Liu Ping , Du Ya , Jiang Xiao Ze , Sun Bin , Yang Wei Zhong , Zhu Mei Fang
Published: June 2017

To prepare alpha zirconium phosphate (α-ZrP) with high interlayer distance, grafting ratio and thermal stability, 1,2-epoxypropane was used to modify α-ZrP as the epoxy group reacting with P-OH on the external and internal surfaces of α-ZrP to form P-O-C bonds after small amines pre-intercalation. Different characterization techniques were used, including X-ray Powder Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Thermo-Gravimetric Analysis (TGA) and Carbon Mass Nuclear Magnetic Resonance (13C MAS NMR). The results of XRD confirmed the pre-intercalation of amino-propane and the intercalation of 1,2-epoxypropane, as the interlayer distance increased from 7.5 Å to 16.9 Å and 15.3 Å, respectively. FT-IR and 13C MAS NMR results confirmed the formation of P-O-C bonds between 1,2-epoxypropane and α-ZrP. TGA analysis showed that the grafting ratio of 1,2-epoxypropane was 19.44%.
Doxorubicin Loading Capacity of Shell Cross-Linked Micelles with pH-Responsive Core as Anticancer Drug Delivery Nanocarriers
Authors: Zhu Shu Yu , Niu Zhong Li , Zhang Xiao Ting , Wang Dan Yue , Xu Jia Ming , Sun Bin , Zhu Mei Fang , Jiang Xiao Ze
Published: June 2017

Detailed studies were performed to probe the effects of the cross-linking layer microstructure of pH-responsive shell cross-linked (SCL) micelles on the loading capacity of doxorubicin (DOX). Well-defined poly [(ethylene glycol)-block-2-(dimethylamino) ethyl methacrylate-block-2-(diethylamino) methacrylate] (PEG-b-P(DMA- co-QDMA)-b-PDEA) copolymer with “clickable” moieties in the middle block by the quaternization with propargyl bromide dissolved molecularly in acidic solution; micellization occurred at alkaline solution to form three-layer “onionlike” micelles constituting PDEA cores, P(DMA-co-QDMA) inner shells, and PEG coronas. Two types of cross-linker bearing azide group: 1,6-bisazidehexane and bis-(azidoethyl) disulfide were utilized to prepare the SCL micelles with different cross-linking layer microstructure via click chemistry at basic aqueous media. The results showed that two types of SCL micelles possessed excellent stability. In neutral solution, these SCL micelles still maintained structural integrity, and the average hydrodynamic diameter of SCL micelles 1 and SCL micelles 2 increased to 80 nm and 90 nm, respectively. In the acidic solution, due to the complete protonated of the PDEA core, the sizes of the two types of SCL micelles increased to 95 nm and 110 nm, respectively, which were favorable for the diffusion of the encapsulated drug in the core. Moreover, the cross-linking degree had no effect on the size of SCL micelles. The loading efficiency and loading content of the SCL micelles were significantly better than those of the uncross-linked micelles, and loading capacity did not vary with degree of cross-linking. However, the SCL micelles 1 demonstrated better loading capacity. This study could be a guidance for the future research on the effects of the cross-linking layer microstructure on controlled doxorubicin release.
Electromagnetic Shielding Effect of Aluminum Foam in 10~500 kV Electrical Substations
Authors: Yang Qian Qian , Qian Wen Xiao , Liu Jing Yuan , Chen Ming , Li Hao , Zhang Yang
Published: June 2017

With the growing attention drawn to the electrical substation electromagnetic environmental problem, the application of material with electromagnetic shielding effect gains more and more popularity. This work evaluated the electromagnetic shielding effect of aluminum foam in 10 kV Xifaxian transformer dado and three electrical substations, a 66 kV Niluo substation, a 220 kV Hexi substation and a 500 kV Keerqin substation. 304L stainless steel and its composite material were also used as a comparison. By comparing with the environmental data, it showed that the power frequency electric field intensity next to the transformer of 500 kV Keerqin substation was slightly higher than the national standard, whereas the other power frequency electric field and magnetic induction intensities were lower than the limit values. The power frequency electric field and magnetic induction intensities attenuated with the increase of measuring distance from enclosing wall. 304L stainless steel, aluminum foam and their composite materials all had certain electromagnetic shielding effect. Aluminum foam and composite materials had almost the same shielding effect for power frequency electric field, which was slightly better than 304L stainless steel. Unlike the electric shielding effect, the magnetic shielding effect of aluminum foam was significantly superior to that of the 304L stainless steel. Meanwhile, their composite material had the best one.
Effect of A-EMS above Liquidus Temperature on Structure Refinement of Al-11%Zn-3%Mg-1%Cu-0.13%Zr Alloy
Authors: Guan Tian Yang , Zhang Zhi Feng , Bai Yue Long , Wang Ping
Published: June 2017

The application of Annular Electromagnetic Stirring (A-EMS) for production of high-quality slurry has been examined. Al-11%Zn-3%Mg-1%Cu-0.13%Zr alloy was used to investigate the effect of A-EMS at various temperatures above liquidus on structure refinement. The results indicate that the grain size was reduced greatly and the homogeneous structure was achieved. Instead of the case in tradition, the nucleation particles gradually formed and the enhanced grain refining efficiency can be mainly attributed to an instantaneous nucleation of numerous heterogeneous nucleation of Al3Zr in the superheating melt under A-EMS.
Online Measuring Method of Interlaminar Cracks of Laminated Composite Based on Image Processing Technology
Authors: Yan Li Li , Zhang Yun He , Li Ke Xin , Fang Jing , Wang Qing Wen , Zhu Bo Lin
Published: June 2017

In order to obtain a real-time interlaminar crack fracture behavior of the laminate composites, in this paper we propose a method of extracting and measuring of interlaminar crack of laminated composite materials based on 2D image analysis via the Matlab software. Extracting the main crack image were conducted using the Matlab script including four different algorithms: the binarization, region growing, morphological, and skeleton thinning, and then a main interlaminar crack image with 1 pixel width were obtained. The length of the main crack was calculated through the sum of pixels of the skeletonized object. The calculated result was closed to the measured result, and the difference between the calculated value and measured value was 0.2%, which can prove the accuracy of the method in present work. The proposed method is of high precision, with strong anti-inference ability and experimental data is stable and reliable, which is helpful to study the crack propagation behavior of laminated composite materials.
Extraction of the RO Phase from Steel Slag
Authors: Cui Su Ping , Wang Xue Li , Wang Jian Feng , Liu Hui
Published: June 2017

Through the XRD and XRF analysis of the converter steel slag, we can identify the chemical components and the mineral phase and ensure the extraction method of RO phase from steel slag. The possibility of the extraction of silicate phase from steel slag with Salicylic acid ethanol (SAE) solution was studied firstly. Then, the effect of dissolution temperature of steel slag, dissolution time of the samples, concentration of salicylic acid and specific surface area of steel slag on the extraction mass of silicate phase were analyzed by orthogonal experiment, and the optimum experiment conditions of the extraction of silicate phase from steel slag with SAE solution were concluded. Finally, the RO phase was obtained by the extraction and separation of the intermediate phase from steel slag using potassium hydroxide-sucrose (KOSH) solution. The effect of extraction was determined by detecting the chemical and mineral composition of the extracted residue with XRD and XRF. The results show that the SAE solution can be used to extract the silicate phase from steel slag and the best extraction conditions were 40 degrees of dissolution temperature, 3 h of solution time, salicylic acid concentration 0.2 g/ml and the specific surface area of steel slag 600 m2/kg. Then the intermediate phases (mainly C2F) from steel slag were extracted by KOSH solution, which can get a relatively pure RO phase. The experiment provides a basis for further exploring the cause of the difference in activity of RO phase and improving the utilization ratio of steel slag.
Influence of Yb Modification on the Microstructure and Mechanical Properties of A356.2 Aluminum Alloy
Authors: Zhang Shao Chen , Leng Jin Feng , Li Chen Xue , Teng Xin Ying
Published: June 2017

A356.2 aluminum alloy (Al–7Si–0.35Mg) has been widely used in automotive and aircraft industries. Previous studies found that the metamorphism effect of rare earth is better than other type of elements because of long modification time and good stability. The influence of Yb addition (0%, 0.2%, 0.4% and 0.6%) and T6 heat treatment on A356.2 alloy has been investigated in this work. The microstructures and mechanical properties of the specimen after T6 treatment were examined by optical microscope, scanning electronic microscope and tensile tests. Experimental results showed that Yb could reduce the size of α-Al and change the Si morphology from needle-like to fine spheroidal particles. With the increase of Yb content, the ultimate tensile strength increased gradually. When adding 0.4%Yb, the alloy achieved the highest ultimate tensile strength (252 MPa) and hardness (97.3HB), 10.12% and 37.66% higher than the alloy with no Yb addition. Tensile fracture analysis showed that the fracture mechanism for A356.2 aluminum alloy after T6 treatment is transgranular/intergranular mixed mode of fracture.
Microstructure Evolution and Mechanical Properties of AZ61 Mg Alloy Processed by Two-Pass Friction Stir Processing
Authors: Luo Xi Cai , Zhang Da Tong , Zhang Wen , Qiu Cheng
Published: June 2017

Friction stir processing (FSP) has been considered as a promising technique for grain refinement. In this study, two-pass FSP was conducted under water to enhance the cooling rate during processing, and a fine-grained AZ61 magnesium alloy was prepared through this method. Compared with one-pass FSP, the microstructure of two-pass FSP alloy is more homogeneous and finer, with an average grain size of 1.8 μm. Both the tensile strength and ductility of the two-pass FSP sample are improved due to grain refinement. A tensile elongation of 31.8% was achieved in the two-pass FSP sample. The microstructure evolution mechanism during the processing was discussed based on the microstructure examination.
The Effect of the Erbium Content on the Microstructure and Mechanical Property of 6061 Aluminum Alloys
Authors: Lv Wen Jian , Li Bo Long , Qi Peng , Nie Zuo-Ren
Published: June 2017

The 6061 aluminum alloys with different content of erbium were prepared. The erbium content was optimized by measurement of grain refining effects and tensile strength. After solid solution treatment of the alloy with optimized erbium content at 505 °C ~ 595 °C for 4 h. and then ageing at –160 °C ~ 200 °C for 3 h., the grain size decreased with the content of erbium, achieving the most effective grain size refinement at the erbium content of 0.15wt.%. The tensile strength of as-cast alloy could reach up to 243 MPa at the erbium content of 0.15%. -Combined with the microstructures and mechanical properties, the erbium content of 0.15% was the optimized content, and heat treatments of ageing at 180 °C for 3 h. followed by solid solution at 565 °C for 4 h were suggested.
Effects of La Microalloying on Microstructure Evolution of Pure Copper
Authors: Wu Jin Hu , Zhang Shi Hong , Chen Yan , Li Hai Hong , Liu Jin Song
Published: June 2017

The absorptivity of La in pure copper and the effects of La microalloying on microstructure evolution of pure copper were studied by adding different La contents to pure copper under vacuum condition. The microstructure of copper ingots with different La contents were synthetically analyzed by means of optical microscope (OM) and scanning electron microscope (SEM), and the content of La in ingots was tested using inductively coupled plasma-atomic emission spectrometry (ICP-AES). The results showws that the absorptivity of La in pure copper was more than 90% under vacuum condition and the burning rate was mainly determinated by autoxidation of La and the reaction with impurity elements in copper. The microstructure of copper ingot was refined with La addition. The columnar to equiaxed transition (CET) occured with 0.14% La addition and the microstructure of copper ingot was full equiaxed grains when La content was 0.16%. The CET mechanism was that the constitutional supercooling in copper melt was increased with La addition. The tensile strength of copper alloys could be improved slightly, while the elongation was decreased a little after La alloying.
Evolution of LPSO Structure of Mg-11Gd-4Y-2Zn-0.5Zr Alloy during Hot Compression Deformation at Different Temperatures
Authors: Yin Xue Yan , Yu Jian Min , Zhang Zhi Min , Qi Hong Na
Published: June 2017

The deformation behavior and microstructure evolution of LPSO phase of Mg-11Gd-4Y-2Zn-0.5Zr magnesium alloy were investigated. This alloy was deformed by hot compression using Gleeeble 3500 thermal simulation machine at different temperatures. The microstructure was analyzed by optical microscopy (OM), scanning electron microscopy (SEM) with spectroscopy (EDS) and XRD. The results showed that the kink bands of LPSO structure of Mg-11Gd-4Y-2Zn-0.5Zr alloy, after thermal compression processing, aggravated as temperature increasing. The fine lamellar LPSO phase could be observed in the alloy. At 450 °Cand 500 °C, some fine lamellar LPSO phase in the grain had been broken into short rod or small block forms, meanwhile, a new rod-like LPSO structure appeared along the grain boundary. Moreover, the decomposition of LPSO structure was more obvious with the increasing of temperature. During hot compression deformation, the segregation of Y, Zr had eliminated partially and the diffraction peaks of W-phase had disappeared. Moreover, there was an increase in hardness as the dispersion distribution of LPSO phase increased.
Thermal Stability of Nanocrystalline Ti6Al4V Produced by Surface Mechanical Attrition Treatment
Authors: Yao Quan Tong , Xing Meng Nan , Zhang Guang Lan , Tong Wei Ping
Published: June 2017

A pollution-free nanocrystalline layer was prepared on the surface of Ti6Al4V by surface mechanical attrition treatment (SMAT). The nanocrystalline samples were vacuum annealed at various temperatures and for different periods of time. The microstructure and thermal stability were characterized by X-ray (XRD), scanning electron microscopy (SEM) and, transmission electron microscopy (TEM). The results showed that the nanocrystalline Ti6Al4V presented a satisfactory thermal stability with the annealed temperature below 650°C. The critical growth temperature for nanocrystalline Ti6Al4V is 100°C higher than that for pure titanium.
Effect of Trace Ce and B Additions on the Mechanical Properties of Nb-3Si-22Ti Alloys
Authors: Wu Mei Ling , Guo Feng Wei , Li Ming , Kang Yong Wang , Han Ya Fang
Published: June 2017

The Nb-Si system ultrahigh temperature alloys were prepared by vacuum non-consumable arc melting. The influence of micro-alloying elements of B and Ce on the hardness, room-temperature fracture toughness and compressive strength at 1250°C of the Nb-22Ti-3Si alloys was investigated and estimated systematically. The results showed that the hardness of the Nb-22Ti-3Si alloy increased obviously with trace B addition, but decreased slightly with trace Ce addition. The room-temperature fracture toughness of the Nb-22Ti-3Si alloy was degraded by the Ce addition but improved by the trace addition of B. The trace addition of B improved the compressive strength of the alloy at 1250°C. In contrast, the trace Ce addition degraded the compressive strength at 1250°C. The relationship between the microstructure and the mechanical properties was discussed.
Effect of Homogenization Temperature on the Microstructure and Property of 6061 Aluminum Alloy with Erbium
Authors: Dong Sha Sha , Li Bo Long , Lv Wen Jian , Qi Peng , Nie Zuo-Ren
Published: June 2017

The microstructure and mechanical properties of as-homogenized 6061 aluminum alloy with 0.2wt.% Er were investigated. The microstructures of the as-casted and homogenized alloys were analyzed using optical microscopy (OM) and scanning electron microscopy (SEM). Energy dispersion X-ray spectroscopy (EDS) was used to analyze the phase chemical composition. The results showed that the homogenizing treatment had a significant influence on the precipitate morphology of the alloy. With increasing homogenization temperature, the long strip-like Fe-rich grain distributed on the boundary phase became discontinuous and sparseness, transforming to short rod and granular shape. In addition, the Fe-rich phase with a large fish-bone structure became smaller. During homogenizing treatment, a large number of dispersive Mg2Si phase appeared inside grains, and large number of the phases containing Er were dissolved into the matrix.
Influence of Heat Treatment Temperature on the Microstructures and High Cycle Fatigue Properties of DD6 Single Crystal Superalloy
Authors: Xie Hong Ji , Li Jia Rong , Yue Xiao Dai
Published: June 2017

The effect of heat treatment temperature on the microstructure and the high cycle fatigue property of DD6 single crystal superalloy was investigated. After standard heat treatment, the alloy was hold at 1200°C and 1300°C for 1h respectively, and then air-cooled. The results showed that after heat treatment at 1200°C for 1h, the size of γ′ particles became slightly larger and quite unevenly, at the same time, the serrated γ/γ′ interface appeared. After heat treatment at 1300°C for 1h, the small irregular γ′ particles re-precipitated. In addition, a small number of fine secondary γ′ particles were also observed in the matrix channel of the alloy after primary aging of 1200°C/1h and 1300°C/1h. The high cycle fatigue properties of the alloy by standard heat treatment were higher than that of the alloy by 1200°C/1h and 1300°C/1h, but the decreased degree of 1200°C/1h was much bigger than that of 1300°C/1h. Analysis on fracture surfaces of the alloy at 800°C demonstrated a quasi-cleavage mode.
Hot Deformation Behavior of AA-FGH720Li Superalloy
Authors: Wang Xu Qing , Peng Zi Chao , Zhang Min Cong
Published: June 2017

The hot deformation behavior of FGH720Li superalloy was investigated by hot compressive tests on Gleeble-1500D thermal simulation test machine in different temperatures and strain rates. The true stress-strain curves were obtained, and based on the deformation data, the constitutive equation of FGH720Li superalloy was built. The Deformation Active Energy of FGH720Li was determined to be Q=787.6KJ/mol. The main deformation modes were dislocation glide and twinning. At the beginning of the deformation, a large number of dislocations generated, glided and scrambled in the alloy, then entwisted to form dislocation cells, which were the recrystallization nucleus. At the later period of the deformation, the dislocation would rotate to easy glide direction through twinning, inducing that the deformation of the alloy ensued. At the same time, the deformation had significant effect on grain refinement and the crushed of the primary particle boundary.
Effect of Annealing on Microstructure and Tensile Properties of Ti-6.5Al-2Sn-4Zr-2Mo-2Nb-1W-0.2Si Alloy
Authors: Zhang Wen Jing , Song Xiao Yun , Hui Song Xiao , Ye Wen Jun
Published: June 2017

The effects of single annealing on microstructure and mechanical properties of an (α+β) high-temperature titanium alloy (Ti-6.5Al-2Sn-4Zr-2Mo-2Nb-1W-0.2Si) were studied by optical microscopy (OM), scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and tensile testing. The results showed that with annealing temperature increasing the volume fraction of primary α phase decreased gradually, while the volume fractions of transformed β structure and secondary α phase increased, and the sizes of these phases became coarse. Elevating the annealing temperature, the room temperature strength didn't change at first and then decreased, the high temperature strength increased gradually, and the ultimate tensile strength and yield strength at 650°C can reach more than 700 MPa and 500 MPa, respectively. Meanwhile, both room temperature and high temperature ductility decreased with the annealing temperature increasing. In order to acquire good strength at high temperature and plasticity at room temperature, the best single annealing temperature is 980°C.
Hot Deformation Behavior and Processing Map of a New High-Temperature Titanium Alloy
Authors: Shi Shao Hui , Chai Li Hua , Li Tao , Cui Yong Shuang , Shi Guo Dong , Xiang Zhi Lei , Chen Zi Yong
Published: June 2017

Isothermal constant strain rate compression testing of a new as-cast high-temperature titanium alloy Ti-6.5Al-11.5(Sn,Zr)-2.5(Mo,W,Nb)-0.25Si-0.1Er was carried out at the deformation temperatures range from 900°C to 1100°C, strain rate range from 0.001 to 1 s-1 and 60% of engineering strain. The deformation behavior of this high-temperature titanium alloy was analyzed based on the stress-strain result, and the constitutive equation based on the hyperbolic sine model and the parameters of Zener–Hollomon was established, showing a close accordance with the experimental value. The hot processing maps based on the dynamic material model and the Prasad’s instability criterion were constructed at strains of 0.3 and 0.6. The maps exhibit two stable deformation domains in the temperature range of 940~960°C and strain rate range of 0.001~0.002s-1, and in the temperature range of 1030~1070°C and strain rate range of 0.02~0.06s-1 with the power dissipation efficiency of 58.5% and 54.5%, respectively.
Effect of Cooling Rate on Hot Tearing Behavior of Mg-9Al-1Zn-0.8Ce Alloy
Authors: Liu Wen Jun , Jiang Bin , Yu Xiao Wei , Pan Fu Sheng
Published: June 2017

The influence of cooling rate (1.5, 0.3 and 0.1 °C/s) on the hot tearing susceptibility (HTS) of Mg-9Al-1Zn-0.8Ce alloy was investigated by taking advantage of numerical simulation and experimental methods. Filling and solidification processes were observed directly using AnyCasting software. The results demonstrated that the reduction of cooling rate increases the residual melt modulus, deteriorate strain and stress concentration at last stage of solidification, and decrease the hot tearing resistance of alloy finally. The maximum value of HTS was obtained at the average cooling rate of 0.1 °C/s owing to the coarse microstructures and bulk Al11Ce3. The minimum value of HTS appeared at the rate of 1.5 °C/s thanks to the finest microstructures and a large amount of eutectic. With the increase of cooling rate, hot tearing susceptibility of the alloy shows a rapid reduction at beginning, and a slow decline followed. Besides, morphology of fracture surface and distribution of secondary phase were further discussed.
Electrical Resistance Relaxation in La55Al25Ni10Cu10 Bulk Metallic Glass
Authors: Liu Bo Yang , Liu Bin Bin , Ye Feng
Published: June 2017

Electrical resistance is always related to the electronic structure of metallic glass and sensitive to structural changes, which provides a more intuitive approach to investigate structure evolution of metallic glasses upon structural relaxation. Electrical resistance relaxation of the La55Al25Ni10Cu10 bulk metallic glass was studied using the standard four-probe method. The electrical resistance of La55Al25Ni10Cu10 bulk metallic glass decreases significantly with the structural relaxation below the glass transition temperature at 445 K. During the subsequent continuous heating, the relaxed specimen shows a reduction in the resistivity decrease at the glass transition. The relaxed electrical resistance caused by the structural relaxation during the isothermal measurement equals the changes of the electrical resistance reduction in the glass transition region in the subsequent isochronal measurements. The calculated relaxed electrical resistance as a function of the annealing time can be fitted by Kohlrausche-Williams-Watts (KWW) equation. The equilibrium value, time constant and the stretched exponent for the isochronal electrical resistance measurements at 445 K are 0.0384, 2390s and 0.66, respectively. The in-situ electrical resistance data recorded in the isothermal annealing process show the same relaxation behavior with fitting parameters 0.0362, 2033 s, and 0.74, respectively.
Research on Mechanical Properties and Wear Behavior at Extremely Low Temperature of a 16Cr-6Ni Austenitic Steel
Authors: Zhao Wei Gang , Xie Guo Liang , Wang Qiang Song , Liu Dong Mei
Published: June 2017

The tensile strength and plastic behavior of the Cr16Ni6 steel were investigated at 298K (298K) and 76K. The yield strength and tensile strength of the alloy increased significantly with lower temperatures, from 990 MPa to 1350 MPa and from 1313 MPa to over 1800 MPa, respectively. Young’s modulus and impact behavior were found when testing temperature decreased. It was revealed from the microstructure observation conducted by scanning electron microscopy (SEM) and x-ray diffraction technique (XRD) analysis that the face-centered-cubic (FCC) structure of the matrix remained stable with a very small amount of tangent phase transformation to martensitie during the tensile tests at 76 K. The matrix grains deformed at 298K were cut apart into many small sub-grains with similar crystallographic orientation in the size of only 60-200 nm wide. Very small amount of dislocation cells or bands observed in the specimens deformed at 76 K, although many sub-grains and areas containing dislocation network were found. The formation of twin-structures along the 1/3(420) planes was found in the deformation areas at 76 K. The improvement of strength was mainly attributed to the fact that it was more difficult for the dislocation slipping along lattice planes at 76 K than at 298K, due to the reduction of the movement and diffusion abilities of atoms. The friction coefficient was found to be a little higher at 93 K than at 298 K due to the bad lubricity of the graphite material at cryogenic temperature.
Numerical Simulation on Filling Process of SiCp/A357 Composites
Authors: Zhang Hao , Zhang Zhi Feng , Zhang Zhen Lin , Bai Yue Long , Xu Jun
Published: June 2017

With high module, high strength and good isotropy, SiCp/Al composite has been widely applied in the fields such as airspace, transportation vehicle and electronic packaging. Stir casting process with advantages of low cost, high efficiency and near-net shape has become a main production method, but the two-phase flow behavior of the SiCp/Al composite during casting process has greatly effect on particle distribution and ultimate properties of casting. In this work, a two-phase flow computational model was developed, and the filling flow process of SiCp/A357 composite based on a benchmark test die was numerically simulated with commercial software Fluent. The effects of SiCp volume fraction and SiCp size on the flow field of SiCp/A357 composite were investigated. The results showed that there existed difference of flow fields between A357 alloy and SiCp/A357 composite, and the simulation results would be helpful to optimize the casting process.
Preparation of AlB12-Type Al-B Alloys
Authors: Wang Qing Liang , Zhang Xing Zhong , Huang Hua Gui , Shen Li , Zhao Jiu Zhou
Published: June 2017

AlB12-type Al-B alloys were prepared by high temperature treatment of AlB2-type Al-B alloy melts with different distribution morphologies of borides. The results show that when using the “immersion” method, the produced AlB2-type Al-B alloy melt (“alloy melt 1”) contain a small amount of AlB12 phase and many boride agglomerations. The AlB2-type Al-B alloy melt produced by using the “vortex” method (“alloy melt 2”) contains no AlB12 phase and exhibits a well dispersion of AlB2 particles. During the high temperature treatment, the AlB2 particles in close contact with each other in the alloy melts are prone to coalescence, causing the formation of relative large AlB12 particles. The high-speed stirring adopted during the high temperature treatment has an effect of prohibiting the coalescence of AlB2 particles in boride agglomerations.
Process and Properties of Ultrafine Silver-Coated Electrolytic Copper Powders
Authors: Meng De Rong , Wang Li Min , Zhang Jing Guo , Hu Qiang , Wang Li Gen , Li Chen Fei
Published: June 2017

The ultrafine electrolytic copper powders were coated by silver using a combination of displacement reaction and reduction method, and the bimetallic core-shell powders with a 10wt.% addition of silver were obtained. The effects of concentration of complexing-dispersing agent and reducing agent on the silver coating layer were studied. The morphology, composition and structure of bimetallic core-shell powders were characterized by scanning electron microscopy, X-ray diffraction and energy dispersive spectroscopy. The oxidation resistance and electric conductivity of the coated powders were also investigated. The experimental results showed that the powders have a better oxidation resistance and higher conductivity using the complexing-dispersing agent of 10g/L EDTA-2Na and the reducing agent n of 30 g/L formaldehyde.
Hot Deformation Behavior and Constitutive Equation of 5E61 Aluminum Alloy
Authors: Liu Ya , Huang Hui , Liu R. , Wen Sheng Ping , Wu Xiao Lan , Gao Kun Yuan , Nie Zuo-Ren
Published: June 2017

The hot deformation behavior of aluminum alloy 5E61 was studied by hot compressive tests using a Gleeble-1500 thermal simulator. The tests were performed at temperatures varying from 250°C to 500°C and strain rates ranging from 0.001 s-1 to 10s-1. The results achieved in the present study showed that the steady flow stress increases with decreasing temperature and increasing strain rate, in accordance with the Zener-Hollomon parameter. The related microstructure is sensitive to deformation temperature, strain rate and strain. The constitutive equation based on true stress-true strain curves has been developed by hyperbolic sine equation with the hot deformation activation energy of 153.907KJ/mol. The softening mechanism could be ascribed dominantly to dynamic recovery. The results of TEM observation suggested that Mn-containing particles and Al3(Er,Zr) phase have precipitated in the aluminum matrix and pin the dislocations, which could effectively inhibit the dynamic recrystallization.