bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Al-Ti-B-Sr Master Alloy on the Microstructure and Mechanical Properties of A356 Alloy
Authors: Wu Jian Hua , Zhao Hou Liang , Zhou Ji Xue , Li Wei Hong , Wang Jin , Zhang Lin Lin
Published: June 2017

A356 alloy was refined with a new master alloy of Al-5Ti-B-10Sr. The microstructure and mechanical properties of the refined A356 alloy with different content of master alloy (0, 0.1, 0.3, 0.5 and 0.7 wt.%) were investigated. The results show that the refining effect becomes stronger as the master alloy content increasing from 0.1 to 0.3 wt.%, and then shows slight decrement until 0.7 wt.%. An optimal combination of the tensile strength (193 MPa) and the elongation (17.8%) of as-cast A356 alloy was achieved with 0.3 wt.% of refining master alloy. Compared to the non-modified A356 alloy, the tensile strength and the elongation were improved by 10% and 242%, respectively.
Strengthening Effects of Single Particle with Different Mechanical Property on Ultra-Thin Rolling of AA1235 Aluminum Alloys
Authors: Xia Cheng Wei , Zhu Y.Z. , Liu Ran , Fan Wei Long , Li Xiao Hui
Published: June 2017

In aluminum foil rolling, the secondary particles may lead to stress concentration at the boundary between these particles and the matrix. Different types of particles would result in stress concentration at different levels. The three dimensional finite element modeling (3D-FEM) was used to simulate the effect of the particles with different hardness on mechanical properties of the matrix of AA1235 aluminum foils in its foil rolling process. The hardness ratio was used to evaluate the mechanical property of foils. It has been found that when the hardness ratio of the particle was similar to that of the matrix (R=1), the interaction mechanism of the dislocations with the particle was dislocation cutting way. When the hardness ratio of the particle to the matrix increased from 1 to 6, the interaction mechanism of the particle with the matrix changed from the dislocation cutting way to the Orowan dislocation bypass way. When the hardness ratio increased to as high as 6, dislocation interacted with the particle only by the Orowan dislocation bypass way.
A Description of Preferential Sites for Vacancy Formation on Grain Boundaries in Copper by Structural Unit Model
Authors: Tong Ke , Ye Fei , Wang Ya Kun , Zhou Feng
Published: June 2017

The preferential sites for vacancies on a series of symmetric tilt grain boundaries in copper have been investigated by molecular dynamics simulation. The regularity of preferential sites for vacancies on these boundaries can be described by the structural unit model. This is essential because of the correspondence between the geometries of the structural units and the local stress field. The vacancies are energetically preferred at the sites with relatively large tensile stress, and these sites are the corner sites of the structural units. Moreover, these preferential sites are mainly related to the structural unit types irrespective of which grain boundary that the structure units locate in. Therefore, the preferential sites for vacancies on various grain boundaries formed by combinations of certain structural units can be readily described and predicted by the structural unit model.
Grain Size and Adhesion Strength of the V8C7 Coatings Produced In Situ
Authors: Wang Xin , Zhong Li Sheng , Zhang Xi , Xu Yun Hua , Wu Hong , Fu Yong Hong
Published: June 2017

The vanadium carbide (V8C7) coating was fabricated by in situ reaction which used gray cast iron and vanadium plate as raw materials providing carbon and vanadium sources, respectively. The microstructure, phases, and adhesion strength of V8C7 coating were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD) and a single scratch test. The XRD results showed that the coating consisted of V8C7 and α-Fe, with the peaks of (222), (400), (440), (622) and (444) of V8C7 phase were confirmed. Moreover, the average diameter (D) of the V8C7 particles in the range of 432~582nm was calculated on the basis of the Scherrer and Halder-Wagner equations. The critical load of interface between V8C7 and substrate was 98.3 N, which implied that the interface of V8C7 coating /substrate had excellent adhesion strength.
Electrodepositing Process of Ni-W-P/Graphene Composite Coatings
Authors: Lu Yu Xiang , Li Xian Ping
Published: June 2017

The Ni-W-P/graphene composite coatings were prepared in the Ni-based electrodepositing solution and graphene oxide mixture, the effect of stirring modes (including no stirring, mechanical stirring or ultrasonic stirring) on the surface quality of the composite coatings was investigated and the optimum formula of the electrodepositing solution of the Ni-W-P/graphene composite coatings was obtained through the orthogonal experiments in 4 factors and 4 levels. It was determined that ultrasonic stirring was the optimum stirring mode during electrodeposition. The Raman spectrum and EDS have shown that there existed graphene, in addition to Ni, W and P in the Ni-W-P/graphene composite coatings. The surface of the Ni-W-P/graphene composite coatings was smooth and the structure was compact. The average microhardness of the Ni-W-P/graphene composite coatings was improved by 26.7% higher than that of the Ni-W-P coatings after the heat treatment of 600°C.
New Equipment for Production of Super Hard Spherical Tungsten Carbide and other High-Melting Compounds Using the Method of Plasma Atomization of Rotating Billet
Authors: Korzhyk Volodymyr , Kulak L.D. , Shevchenko V.E. , Kvasnitskiy V.V. , Kuzmenko N.N. , Liu X. , Cai Yi Xiang , Wang L. , Xie H.W. , Zou Li Ming
Published: June 2017

In order to ensure high wear resistance of parts and tools, operating at significant dynamic loads in the extreme conditions, the layers different in their function purpose obtained using surfacing methods are widely used. In such surfacing compositions, the powders of high-melting compounds characterized by high hardness and strength, are used as a wear resistant component, for example, alloys of tungsten carbide WC + W2C (cast tungsten carbide), and as binder matrix the plastic and metal alloys are used.The great interest is the development of methods allowing producing powders of cast tungsten carbide and other high-melting-point materials of uniform composition, characterized by a high sphericity of the particles and having higher physical-mechanical properties. The spherical tungsten carbide was produced by plasma atomization of rotating billet. The universal installation for production of super-hard spherical tungsten carbide and other high-melting-point compounds by plasma atomization of rotating billets was designed for industrial application. The results showed that the application of the technology of plasma rotary atomization of rotation billet to obtain granules of powders of high-melting-point materials was promising, in particular tungsten carbide with sphericity over 90%, microhardness HV0.1 more than 3000 kg / mm2 characterized by high flow ability more than 7.5 s/ 50 g. Due to the use of new materials and innovative design and technological solutions the high reliability, maximum interval of technical service, high resource of operating units and executing mechanism of the equipment were ensured. Due to the use of new high-power plasma system with power supply source with high efficiency coefficient and improved dynamic characteristics, the system of preliminary heating of billets, innovative gas systems, high performance vacuum system, the developed universal system for the production of granules of powders of high-melting-point material were also applicable for the manufacture of spherical powders of metals and alloys, including highly active, and provided lower costs of products (powder) with an increased productivity, economic efficiency of the atomization process and reduced the impact of atomization process on the environment.
Structure Stability and Mechanical Property of Y2O3 Thin Films Deposited by Reactive Magnetron Sputtering
Authors: Yu Peng Fei , Zhang Kan , Du Su Xuan , Ren Ping , Wen Mao , Zheng Wei Tao
Published: June 2017

Y2O3 has a great application potential at reaction barrier coating of high-temperature composites due to its high thermodynamic stability and high melting point, and the phase structure stability at high temperature and structure dependent mechanical property are key parameters for this application. Y2O3 thin films were deposited on silicon (100) wafers by DC magnetron sputtering with various oxygen partial pressure and substrate bias, and then vacuum annealing at 1000°C was performed to investigate the phase structure stability. The microstructure, stress and hardness of as-deposited and annealed Y2O3 thin films were explored by X-ray diffraction, transmission electron microscope, and nanoindenter. The result showed that as-60 bias voltage was applied to substrate, cubic-c phase formed regardless of variation of oxygen partial pressure, and the cubic-c phase remains stability and crystallinity became better after annealing at 1000 °C.In addition, the hardness and modulus also just had minor changes as a function of oxygen partial pressure. As oxygen partial pressure was kept at 0.043 Pa, phase transition from cubic-c to monoclinic-b phase took place with increasing substrate bias, accompanying by the increment of hardness and modulus, and 1000 °Chigh-temperature annealing resulted in that as-deposited monoclinic-b phase transforms to cubic-c phase.
Preparation and Properties of Heat-Dissipation Coating Filled with Carbon-Based Filler
Authors: Gao Yue , Mao Qian Jin , Wang Hai , Wang Zi Ming , Cui Su Ping
Published: June 2017

Aiming at the heat dissipation of equipment, and based on ANSYS finite element simulation of thermal conductivity of coatings, the heat-dissipation coating filled with graphite and carbon nanotubes respectively, which integrates heat conduction (high thermal conductivity) and radiation (high emissivity), was successfully prepared by the method of solution mixing. Meanwhile, the effects of filler content, type and shape on thermal conductivity and emissivity of the coating were also investigated. The results indicate that the rising tendency between the simulated data by FEM and experimental value is consistent, which has a certain directive significance. In addition, graphite can improve the thermal conductivity and emissivity of the coating effectively; however, the emissivity decreases when the content exceeds 23.08%. The carbon nanotubes can improve the thermal conductivity and emissivity simultaneously, the thermal conductivity is 2.3 times that of pure resin, and the emissivity is up to 0.91 at the 2.0% mass fraction of carbon nanotubes.
Dielectric and Conduction Properties of Lu3NbO7 Transparent Ceramic
Authors: An Li Qiong , Wang D.S. , Fan Run Hua , Dong Li Hua
Published: June 2017

The dielectric response and electrical conduction of Lu3NbO7 transparent ceramic produced by spark plasma sintering were investigated. Lu3NbO7 transparent ceramic exhibited low frequency dielectric dispersion and a peak in dielectric loss, shifting to higher frequency at high temperatures. This indicated space charge polarization and broad relaxation time, confirmed by impedance and modulus spectra. The Nyquist plot shows the dominant grain effect in the electrical conduction. The AC conductivity of Lu3NbO7 transparent ceramic is 4.18×10-2 S m-1 at 1073 K, with an activation energy of 1.30 eV.
Multi-Walled Carbon Nanotube-Alumina Nanocomposites with Dielectric Resonance-Induced Negative Permittivity Behavior
Authors: Cheng Chuan Bing , Fan Run Hua , Qian Lei , Wang Zhong Yang , Xie Pei Tao , Dong Li Hua , Yin Yan Sheng
Published: June 2017

The multi-walled carbon nanotube/alumina (MWCNTs/Al2O3) nanocomposites embedded with the shortened MWCNTs were prepared by pressureless sintering. The microstructure, conductive behavior and complex permittivity spectra of the composites were investigated. It was found that MWCNTs, which were shortened to low aspect ratio by the controllable acid and ultrasonic treatment, uniformly dispersed in the Al2O3 matrix. A unique dielectric resonance-induced negative permittivity behavior was observed in the composites with high MWCNTs content. The negative magnitude of permittivity was small (~-50) in the testing frequency. The dielectric loss peaks being accompanied by dielectric resonance moved to the higher frequency with increasing MWCNTs content. Those composites underwent a capacitive-inductive transition with increasing frequency and their conductive mechanism was hopping conduction. This work is beneficial to explore the generation mechanism of negative permittivity, and will greatly facilitate the practical application of metamaterials.
Carbon-Doped Sb-Rich Ge-Sb-Te Phase Change Material for High Speed and High Thermal Stability Phase Change Memory Applications
Authors: Li Tao , Wu Liang Cai , Song Zhi Tang , Song San Nian , Rao Feng , Liu Bo
Published: June 2017

Carbon-doped Sb-rich Ge-Sb-Te (Sb-CGST) is proved to be a promising candidate for phase change memory because of it high crystallization temperature (higher than 200°C) and 10-year data retention temperature (higher than 120°C). The carbon-doped Sb-rich Ge-Sb-Te (Sb-CGST) films were deposited on SiO2/Si (100) substrate by RF magnetron co-sputtering using CGST alloy target (a GST target containing 16 at. % C) and Sb targets at room temperature. The content of Sb in the films was controlled by adjusting the sputtering power ratio of CGST and Sb. The results showed that both of these two properties increase firstly and then decreases with increasing the content of Sb, which are superior to that of Ge2Sb2Te5. Furthermore, Sb-CGST based PCM cells were fabricated to investigate the property of material. 6ns pulse could realize SET operation, and 3.2 x 10-11J energy can realize RESET operation.
Surface Plasmon Resonance Effect of the MoS2/Ag System
Authors: Ma Xi Ying , Mao Hong Ming , Meng Miao Fei
Published: June 2017

Detection of organic materials or heavy ions using the surface plasmon resonance (SPR) effect of the MoS2/Ag system was studies. We found that the reflectivity of the SPR system was sensitive to the incident angle of light, dielectric constant of the detected samples, wavelength of light, and thickness of the Ag film. It reached an extreme minimal value (EMV) at an extreme angle θ. As the dielectric constant of the samples was increased from 1.0 to 3.25, θ increased, enabling high-resolution detection. θ slightly decreased with the thickness of the Ag film changed from 300 to 700 nm for a given detected sample while the EMV of reflectivity increased. Moreover, the reflectivity curves were overlapped when the wavelength of light and the thickness, d of the Ag film both increased from 400 to 700 nm, showing synchronous effect. The results showed that MoS2 was a suitable material for the detection of a wide range of samples and could replace the prism.
A New Green Approach for Recovery of Metallic Tungsten through Electrolysis of Tungsten Carbide Scrap Anode in Molten Salts
Authors: Li Ming , Liu Qing Qing , Xi Xiao Li , Nie Zuo-Ren
Published: June 2017

In this study, a new green approach has been developed for the recovery of tungsten by using tungsten carbide (WC) scrap material as consumable anode in LiCl-KCl molten salts at 773 K to produce metallic tungsten. The feasibility of the direct electrochemical dissolution of WC anode into metallic tungsten was evaluated based on the experimental verifications and electrochemical methods. The effects of the main technical parameters, including the cell voltage, electrolysis time and electrolysis temperature, on the dissolved condition of anode were studied and the optimal anode parameters were obtained. It was found that a large electrolytic voltage, high electrolytic temperature and long electrolysis time would be favorable for the dissolved state of the tungsten carbide anode under the same conditions. The cathode product was analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that the tungsten particles with a diameter of 100 nm could be prepared by this process in a molten salt bath. Linear sweep voltammetry was applied to investigate the dissolution of WC anode, and showed that the WC scrap material could be used as consumable anode to produce tungsten powder. Other electrochemical techniques including cyclic voltammetry , square-wave voltammetry and chronopotentiometry were employed to explore the electrochemical properties of tungsten ion derived from WC anode in LiCl-KCl melts. These results confirmed that electroreduction of tungsten ion in the melts proceeded in one step with four exchanged electrons.
Modification of Nano Spherical-Like MnOx/TiO2 Catalysts with F-Doped
Authors: Xie Jun Lin , Li Feng Xiang , Cui Hai Feng , He Feng , Qi Kai
Published: June 2017

A series of spherical-like MnOx/TiO2 catalysts with F-doped were prepared by using sol-gel method and investigated for low-temperature selective catalytic reduction (SCR) of NOx with NH3 at the temperature ranging from 100 °C to 200 °C. The 0.07Ce-MnOx/TiO2 catalyst shows the highest activity and yields 95% NO conversion at 200 °C. With the help of XRD, TGA, H2-TPR, NH3-TPD, BET and TEM, the structures and properties of the catalysts were characterized. The results show that it is a fine modifier for TiO2 support with appropriate amounts of F doping, and F ions can enter into TiO2 lattice, reducing the formation of rutile TiO2 and the crystallization of MnOx. However, MnTiO3 was generated in the catalysts with excess F doping. This would cause larger diameter of spherical particle and smaller surface area. But the amounts of the surface acid sites increased, and the reduction ability of catalysts was enhanced, which is beneficial for catalytic activity of the catalysts.
Fabrication and Stability of CoAl2O4 Ceramic Pigment for 3D Printing
Authors: Song Yuan , Zheng Yuan Lin , Tang Yu Fei , Yang Hai Bing
Published: June 2017

Ceramic pigment is the key component of the ink color in the 3D printing process of ceramic products. The color performance and stability of ceramic pigments after calcination still need to be improved. In the present study the cobalt aluminate (CoAl2O4) ceramic pigment powders were fabricated by sol-gel method. The effects of fabrication processes on color properties of CoAl2O4 ceramic pigments were investigated. The compositions and morphologies of CoAl2O4 ceramic pigment powders were characterized. The stability of CoAl2O4 ceramic pigments was discussed. The results showed that the CoAl2O4 ceramic pigment with high chroma was obtained at calcination temperature of 1200°C and the Co/Al ratio is 1:3. The Zeta potential of the fabricated CoAl2O4 ceramic pigment powders in aqueous solution was-66.2 mV, which represented good dispersion stability. The chroma and saturation of the CoAl2O4 ceramic pigment increased owing to that the oxide solid solution in the spinel structure increased after being sintered at 1300 oC.
Effects of Aging on the Low Temperature Properties of Asphalt Binder and its Mixture
Authors: Cui Zhang Chao , Pang Ling , Zhang Nai Zhi , Zhang Xue Mei , Li He Chuan
Published: June 2017

Effect of aging on physical properties of asphalt binder was studied. The relationship between degradation of the low temperature properties of asphalt binder and asphalt mixture was also investigated. After the thin film oven test (TFOT) with different aging time, the AH-70 binder and the SBS modified asphalt binder were used to prepared asphalt mixture samples. The binder was characterized using penetration, ductility and Beam Bending Rheometer (BBR), and the low temperature cracking resistance of asphalt mixture was studied by Three-point Bending Fracture (TBF). The correlation between different physical parameters of binder, as well as between different aging properties of the binder and asphalt mixture, was examined. The results showed that aging influenced binder physics significantly, and resulted in a decline in the properties of low temperature cracking resistance of asphalt mixture. Although, aging susceptibility of binder and asphalt mixture may be ranked differently when different evaluation methods ware used, a strong correlation was observed between the aging of binder and asphalt mixture.
Influence of Quality and Replacement Rate of Recycled Coarse Aggregate on the Frost Resistance of Recycled Concrete
Authors: Yue Gong Bing , Li Qiu Yi , Luo Jian Lin , Guo Yuan Xin
Published: June 2017

Compared with natural aggregate, the content of hardening cement in recycled aggregate is larger, which leads that the water absorption of recycled aggregate is larger and its performance such as robustness is poorer. And the engineering field pays much attention to the problem of the recycled fine aggregate which can be used in the durability requirements of recycled concrete or not. Using the method of fast freezing and thawing the influence of quality and replacement ratio of recycled coarse aggregate on the frost resistance of recycled concrete was researched basing on ordinary concrete frost resistance performance. The results showed that, in terms of the frost resistance capacity, the order is in: ordinary concrete>high-quality recycled coarse aggregate concrete>normal quality recycled coarse aggregate concrete. After 250 freeze-thaw cycles, the mass loss rate of general quality recycled coarse aggregate concrete is 5%, relative dynamic elastic modulus is 60% when replace rate was 100%.
Electromagnetic Shielding Effectiveness of Nickel Fiber-Reinforced Cement Composites
Authors: Yao Wei Lin , Xiong Guo Xuan , Yang Ying
Published: June 2017

The nickel fiber was added into the cement-based composite materials as a shielding medium. Influences of the three different types and amount of dispersants and weight fraction of nickel fiber on the electrical conductivity and electromagnetic shielding effectiveness of the cement matrix composite were discussed. The conductivity of cement based composite materials and the uniformity distribution of shielding medium were characterized by four-point probe meter and scanning electron microscopy, respectively. Electromagnetic interference shielding effectiveness in the frequency range of 1 MHz to 1500 MHz was characterized by coaxial cable method. The results indicated that the improved dispersion of nickel by incorporation of dispersants might yield the enhancement of the electrical properties of nickel fiber-reinforced cement composites. When the dosage of methyl cellulose reaches 0.4 wt.%, the pre-dispersing nickel fiber enhances the electrical conductivity of the cement-based composite materials significantly. With the increase of fiber volume fraction, the shielding effectiveness and trend of frequency change of the corresponding fiber-reinforced concrete were enhanced. When the content of nickel fiber powder was 9.0 vol.%, the conductivity was 2.65×10-3 s·cm-1, and the average shielding effectiveness of the specimen in 1MHz-1500 MHz was about 21.78 dB, with the maximum shielding effectiveness of 24.48 dB and the minimum shielding effectiveness 19.85 dB.
Microstructure and Properties of C-S-H/PCE Nanocomposites
Authors: Shen He Qing , Wang Zi Ming , Liu Xiao , Pang Xiao Fan , Xue Long
Published: June 2017

Different dosage of TPEG-polycarboxylate (PCE) copolymers were used to prepare the calcium-silicate hydrated (C-S-H)/PCE nanocomposites by precipitating C-S-H from Na2SiO3·9H2O and Ca (NO3)2·4H2O in the PCE solution. The composition and structure of the prepared C-S-H/PCE nanocomposites were characterized by XRD, SEM, FTIR methods, and the early strength of mortars was measured. The results show that structural investigation of the C-S-H/PCE nanocomposites via X-ray diffraction revealed a semi-crystalline composition, and the PCE polymers were adhered the surface of C-S-H particles in the composite. The preparation of C-S-H /PCE nanocomposites enhanced markedly the early strength of mortar, and when the dosage of PCE copolymers was up to 30%, the early strength enhancing effect was the highest, the early flexural strength increased up to 100%, and early compressive strength increased up to 120%. Therefore, C-S-H /PCE nanocomposites can improve the early strength of mortar effectively since it can lower the barrier of nucleation of the products, promote the nucleation and inhibit the growth of large grains effectively.
Dielectric Behavior of Barium Titanate/Carbon Fibers Composites
Authors: Wang Zhong Yang , Li Xin Yan , Fan Run Hua , Xie Pei Tao , Sun Kai , Fan Guo Hua , Hou Chuan Xin , Zhang Xiang
Published: June 2017

Conductor–insulator composites have been extensive researched for high dielectric constant. Most of them concentrated on metal polymers or metal ceramics. Barium titanate–carbon fibers composites were prepared by using a solid state reaction process with carbon fibers contents ranging from7 vol% to 23 vol%. Due to the high-aspect-ratio of carbon fiber, it was easy to produce a conducting network at much lower volume fraction. FESEM images illustrated that the carbon fibers influenced the densification and microstructure of the ceramics. Besides, addition of carbon fibers led to increase in dielectric permittivity, also had effects on the dielectric loss and ac conductivity. The dielectric and conductivity properties as a function of carbon fibers volume fraction were explained by the percolation theory.
Effects of Co, Zr Additions on the Magnetic Properties of Nanocomposite Nd2Fe14B/α-Fe Magnets
Authors: Li Bing Bing , Ma Yi Long , Li Chun Hong , Yin Xue Guo , Zheng Qiang , Sun Jian Chun , Guo Dong Ling , Shao Bin , Zeng Wen
Published: June 2017

The effects of the additions of Co, Zr on microstructure and magnetic properties were studied for hot-deformed (HD) nanocomposite Nd11.5Fe81.5-xNb1CoxB6 (x=0, 2, 4, 8) and Nd11.5Fe82.5-xZrxB6 (x=0, 1) magnets, respectively. The remanence of hot-pressed (HP) magnets increased with increasing Co content firstly, but decreased when Co content was more than 2 at. % for HD magnets. Also the intrinsic coercivity (Hci) and maximum energy product ((BH)m) of HD alloys increased firstly, and then decreased with further increasing Co content. The maximum (BH)m of 24 MGOe was obtained at 2 at.% Co addition. Zr addition can improve significantly the c-axis alignment and magnetic properties of HD nanocomposite magnets, and HD Nd11.5Fe81.5Zr1B6 magnet with 1.5 wt.% Zn addition showed enhanced properties with Hci of 7100 Oe and remanent magnetization (Mr) of 1.06 T. The alloys have the structure of plate-like grains, but there are still many coarse grains, which may result from the un-uniform composition in the alloy.
Precipitation Kinetics Analysis of the Cooling Process Following the Solid Solution Treatment of 7B50 Aluminum Alloy
Authors: Kang Lei , Cui Yuan Jun , Zhao Gang , Tian Ni
Published: June 2017

Based on the TTP curves of 7050 alloy, and the continuous cooling curves of 7B50 alloy at different positions of Φ70 mm improved Jominy specimen, the hardness distribution along the thickness direction of 7B50 alloy thick plates was analyzed and predicted by means of the isothermal precipitation kinetics and the quench factor analysis method. The results show that when 7050 alloy is isothermal treated at 200°C~400°C, the exponent n in its Johnson-Mehl-Avrami equation is close to 1, which indicates that the nucleation process of new precipitates is stable. In this equation the coefficient k is 7.420E-03 at 350°C, which indicates that the nucleation and growth rates of new precipitates are very fast. The hardness distribution along the axial direction of the improved Jominy specimen of 7B50 alloy is predicted by the quench factor analysis method. When the distance is no more than 65 mm from the spraying surface of the improved Jominy specimen, the deviation between the predicted and measured hardness of 7B50 alloy in T6 temper is less than 5%. The quench factor analysis method is feasible to predict the hardness distribution along the thickness direction of 7B50 alloy thick plates after quenching and aging. When the quench factor analysis method is extended to predict the actual water spray quenching process of 7B50 alloy thick plates, the average cooling rate is 21.6°C/s in the quench sensitive temperature range of this alloy, at 15 mm from the spraying surface of the plate. At the same position, the corresponding quench factor is equal to 6 and the predicted hardness is 187.4 HV which is equivalent 98.5% of the Hmax (the maximum hardness) of 7B50 alloy in T6 temper.
Impregnation Behavior of Polyamide 6 in Carbon Fibers and the Properties of their Composites
Authors: Hu Yu Fei , Zhang Jian , Wang Biao , Zhang Xue Na
Published: June 2017

Unidirectional carbon fiber (CF) / Polyamide 6 (PA6) composites were prepared by stacking fabrics method. Due to the effect of the textile structure and rough surface of PA6 fabrics, slipping of carbon fibers (CFs) during the stacking process was prevented and uniformity of impregnation was improved. Meanwhile, the usage of PA6 fabrics resulted in the minimum level of void content of composites, which improved the mechanical properties of composites. Additionally, the void content of materials was associated with the mechanical properties of composites. The flexural strength of composite reached 819.58 MPa when its void content was 3.49%. Moreover, a model based on Darcy’s law was developed to simulate the impregnation behavior of PA6 in CFs which was made by stacking fabrics method. The resin flow was observed by using optical microscopy. The evolution of void content in composites was related to the processing parameters (holding time, processing temperature and processing pressure).The comparison between the experimental and simulated data showed that the model was reliable to describe the impregnation process.
Effect of Draw Ratio on the Microstructure of Silk Fibroin/Graphene Oxide Hybrid Fibers
Authors: Zhang Chao , Shao Hui Li , Hu Xue Chao , Zhang Yao Peng
Published: June 2017

In order to fabricate high performance artificial silk, hybrid fibers were dry spun from regenerated silk fibroin (RSF) aqueous solution mixed with graphene oxide (GO) nanosheets. The influence of draw ratio on the microstructure and mechanical properties of RSF/GO hybrid fibers was studied through Fourier transform infrared spectroscopy (FT-IR), synchrotron radiation wide-angle X-ray diffraction, Raman spectroscopy and mechanical testing. The results showed that with increasing draw ratio, both amorphous phase and mesophase of the dry-spun artificial fiber gradually converted to crystals. The orientation of crystals and mesophase changed slightly at low draw ratio, but increased significantly at draw ratios of 3 and 4X. The β-sheet content of silk fibroin and the disorder degree of GO sheets in the fibers also increased with the increase of draw ratio. The initial modulus, breaking strength and breaking energy of the hybrid fibers achieved great improvement at a draw ratio of 4X. The structure evolution of the RSF/GO hybrid fibers may benefit the understanding of the structure-property relationship of other composite fibers.
Preparation and Characterization of Antibacterial Nylon 6 Fiber
Authors: Tang Lian , Wang Dan Yue , Xu Qiu Shu , Wang Chao Sheng , Wang Hua Ping , Huang Qing
Published: June 2017

Due to its excellent mechanical property, dye ability and skin affinity, PA6 has been widely used in apparel, home textiles, military products, etc. However, PA6 fiber is easy to breed bacteria and corroded by bacteria in humid environment. One of development tendency of functional PA6 fiber is to design and develop nylon 6 fiber with excellent antibacterial properties, which is also the research target of this paper. In the present investigation, ZnO antibacterial agent was prepared through sol-gel method, and antibacterial masterbatch was acquired via blending antibacterial agent with PA6 using a twin-screw, then antibacterial PA6 fiber was obtained through melt spinning. The thermal properties, crystallization property of antibacterial PA6 masterbatch were discussed. The effect of drawing ratio on fiber strength, elongation of break, orientation and crystallization was also investigated. The antibacterial properties of antibacterial agent and antibacterial PA6 fiber was analyzed by agar diffusion method. The results of Differential Scanning Calorimetry (DSC) suggests that the antibacterial agent causes the rise of crystallization temperature and crystallization rate. X-Ray Diffraction (XRD) and mechanical testing results reveal that the higher drawing ratio leads to higher orientation and strength of PA6 fiber, lower elongation at break. The addition of antibacterial agent increases the degree of orientation and crystallization, reduces the strength of fiber and tends to form α crystalline in PA6 fiber. Antibacterial tests show that antibacterial PA6 fiber has a good antibacterial performance against Staphylococcus aureus.
High Temperature Resistance of Polyborosilazane/Epoxy Resin Curing System
Authors: Zhang Chen Yu , Liu Yong , Han Ke Qing , Chang Xue Feng , Yu Mu Huo
Published: June 2017

In this paper, Polyborosilazane (PBSZ) was successfully synthesized and used as curing agents for epoxy resin. FTIR, TGA, XRD, SEM were used to analyze the curing mechanism, curing temperature and thermal stability of the curing system. The results indicated that PBSZ could be used as curing agents for bisphenol A epoxy resin when its usage amount was 30-60 wt.% at the temperature between 100 ∼ 150 °C. Additionally, the thermal stability of PBSZ cured epoxy resin samples were better than that of epoxy resin cured with 4, 4-diaminodiphenylsulfone (DDS), showing a higher residual weight at 900°C. As PBSZ content increased, the residual weight of PBSZ cured epoxy resin at 900°C increased. When PBSZ content was 30%, the surface of cured epoxy resins was smooth without obvious defects. However, the surface became coarse when PBSZ content was further increased.
Cellulose/Paraffin Composite Fibers for Thermal Energy Storage and Temperature Regulation
Authors: Xia Wei , Xiang Heng Xue , Chen Wen Ping , Li Yan , Chen Wei , Chen Li Jun , Zhao Jie , Zhu Mei Fang
Published: June 2017

Cellulose is a good bio-based material for rich resources and recyclability. Paraffin is widely used in the field of energy storage and temperature regulation due to its excellent heat storage properties and mature preparation technology. In this paper, the cellulose fibers with energy storage and temperature regulation were prepared by wet spinning process using paraffin as phase change material. Field Emission Scanning Electron Microscope (FE-SEM), X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC) and Thermal Gravimetric Analysis (TGA) were utilized to characterize the morphology structure, crystalline properties, phase transition properties and heat resistance of fibers and so on. The results showed that the fiber surface without holes and paraffin was uniformly distributed in the cellulose matrix, and paraffin was not easily overflow during the process of phase change. Paraffin and cellulose substrate had good compatibility due to the interaction of hydrogen bonding, and 30% of paraffin did not cause a significant impact on the degree of crystallinity and thermal stability of cellulose fibers. Enthalpy of the resultant functional fibers could reach 27.44 J/g, and the thermal decomposition temperature was over 300 °C. The fibers possessed the phase change ability and certain mechanical properties. Furthermore, it was found that the fibers still had good resistance to washing under extreme conditions.
Preparation and Characterization of Stimuli-Responsive Poly(N-Isopropylacrylamide)/Ca-Alginate Hydrogel Fiber by Microfluidic Spinning
Authors: Peng Li , Huan Jia Ni , Gong Jing Hua , Ma Jing Hong
Published: June 2017

Smart hydrogel is a kind of new soft and wet material which can be responsive to external stimuli. Hydrogel fiber owning one dimension size can significantly improve response speed and be easily formed into higher-order assemblies. N-isopropylacrylamide/calcium alginate (NIPA/Ca-alginate) as-spun fiber was generated via microfluidic spinning. Then PNIPA/Ca-alginate hydrogel fiber was prepared through off-chip free radical polymerization of NIPA in the presence of Ca-alginate. The structure and morphology of the hydrogel fiber were characterized by FTIR and SEM. The swelling property and temperature-/pH-response behaviors were also investigated. The PNIPA/Ca-alginate hydrogel fiber had a 3D network porous structure. The thinner the hydrogel fiber, the faster the swelling speed was. Meanwhile, the hydrogel fiber exhibited temperature and pH response.
Allocation of the Environmental Impact in Iron and Steel Industry
Authors: Zhang Yan Jiao , Gao Feng , Wang Zhi Hong
Published: June 2017

Life cycle assessment (LCA) can provide technical support for environmental management in China. However, there is no consensus on allocation method in inventory analysis. According to the World Steel Association (WAS), the environmental impact, life cycle environmental load and environmental benefit of China's iron and steel industry should be considerd when investing scrap iron and steel. The results of this study show that according to the different allocation methods, the environmental impact of China's iron and steel industry will be divided into 3 methods: 1) not considering environmental load and environmental benefit of the environment (Cut-off approach); 2) considering the environmental load or environmental benefits (Waste evaluation method) and 3) considering environmental load and environmental benefits (Recycling benefits method). The environmental impact of Electric Arc Furnace (EAF) steel billet is raising by using the waste evaluation method compared with that of basic oxygen furnace (BOF), which are all decreased by using the cut-off approach. Recycling benefits method compared with Cut-off approach that the BOF hot rolled steel coil (HRC) environmental impact, the environmental impact of EAF steel billet all decreased, and leading the BOF hot rolled steel coil environmental impact to a larger proportion of the environmental impact.
Microstructure and Mechanical Properties of ZK60 Magnesium Alloy Prepared by Multi-Pass Friction Stir Processing
Authors: Lin Jun , Zhang Da Tong , Zhang Wen , Qiu Cheng
Published: June 2017

Friction stir processing (FSP) is a novel severe plastic deformation technique developed in recent years to produce fine-grained structural materials. In this paper, the microstructure and mechanical properties of ZK60 magnesium alloy prepared by the single-pass and two-pass FSP were studied. The first-pass was subjected with 800r/min-100mm/min and the second-pass was subjected with 600r/min-100mm/min. The results show that the coarse second phase was dissolved into magnesium matrix and the α-Mg grains were remarkably refined in stir zone after FSP. The average grain sizes of the single-pass and two-pass FSP alloys were 6.8μm and 6.0μm respectively. The microhardnesses of the specimens were 70HV and 65HV, the ultimate tensile strengths were 276MPa and 272MPa, and the elongations were 31.6% and 42.5%, respectively. Through increasing the processing pass, the microstructure became finer and the second phase is dissolved more thoroughly. The combined effect of grain refinement and second phase dissolved was responsible for the change of mechanical properties.
Effect of TiB on the Nucleation and Growth of α Phase in Ti-6Al-4V-0.1B Alloy
Authors: Yu Yang , Li Hong Jiang , Mi Xun Jun , Gao Qi
Published: June 2017

The effect of TiB on the nucleation and growth of α phase both in as-casted and as-annealed Ti-6Al-4V-0.1B alloy by optical microscopy and EBSD technique. The results show that during the solidification α phases nucleate and grow up in the β phase matrix and the interface between beta matrix and TiB phase. TiB phase acts as a nucleation site for α phase and promotes the nucleation and growth, resulting in refined α colonies in as-cast microstructure. During the furnace cooling process from above β transus temperature, α precipitates is a consequence of its orientation relationship with TiB, which restraints the lath growth. Equiaxed α phase precipitates during the furnace cooling from the above β transus temperature.
Microstructure, Mechanical and Corrosion Properties of 5E61 Alloy
Authors: Liu Pei Liang , Wu Xiao Lan , Wen Sheng Ping , Huang Hui , Gao Kun Yuan , Nie Zuo-Ren
Published: June 2017

The microstructure of Al-6Mg-0.9Mn-0.07Zr-0.2Er (wt.%), registered as 5E61 alloy, were investigated using optical microscopy, scanning electron microscopy and transmission electron microscopy. The results showed that the addition of 0.2 wt.% Er can refine the dendritic structure and form fine and coherent L12 structured Al3(ErxZr1-x) precipitates in the alloy. After a two-stage homogenization (280°C/10h, 460°C/36h), the recrystallization temperature of the alloy with 0.2 wt.% Er is about 15°C higher than that of the alloy without Er. The better recrystallization resistance may be related to the Al3(ErxZr1-x) precipitates, which can pin on dislocations and sub-grain boundaries. The hardness of the cold-rolled alloy with 0.2 wt.% Er is 143HV, which is 5% higher than the alloy without Er. The exfoliation corrosion and nitric acid mass loss test were also performed. The exfoliation corrosion of the alloy is N grade, and the mass loss is only 9.84mg/cm2.
Effect of Trace Element Hf on the Precipitation Process and Recrystallization Resistance of Al-Er-Zr Alloys
Authors: Liu Tong Hui , Wen Sheng Ping , Wu Xiao Lan , Huang Hui , Gao Kun Yuan
Published: June 2017

Vickers hardness and electric conductivity measurements as well as micro-structure analysis were used to investigate the effects of trace element Hf atoms on the precipitation and recrystallization resistance in Al-Er-Zr alloys. The results of the present study indicated that the behaviors of precipitation process in Al-0.04Er-0.08Zr and Al-0.04Er-0.08Zr-0.05Hf (at. %) alloys are similar. When alloys were annealed at 350 °C for 96h, the nanoscale and coherent Al3(Er, Zr) and Al3(Er, Zr, Hf) precipitates form, corresponding to the peak hardness values of 56.2 ± 0.9 (ternary alloy), 58.9 ± 1.5 HV (quaternary alloy), respectively. The higher peak hardness in Al-0.04Er-0.08Zr-0.05Hf alloys mainly benefit from the decomposition of Hf. It was shown that the existence of precipitates could improve the recrystallization resistance obviously. Due to the similar retarding force, recrystallization temperatures of both alloys are almost the same, approximate 450 °C.
Investment Casting Defects of a Turbine Nozzle Made by K465 Alloy
Authors: Li Yang , Li Pei Jia , Chen Xing Fu , Liu Hao Ran , Wu Jian Tao , Li Jun Tao
Published: June 2017

The investment casting defects in a turbine nozzle with size of φ 331mm and thickness 0.7 mm and the number of vanes of 31 have been studied in two aspects, which were the porosity of the turbine nozzle’s inner cone and the cracks of the turbine nozzle’s vanes. ProCAST software was used to analyze the nozzle’s solidification process. A suitable gating system was used to solve porosity issues effectively by changing local thickness and improving solidification conditions. The crack on the nozzle’s vanes was studied and a kind of grain refiner was used to solve crack issues by improving shell strength. In order to manufacture castings with high metallurgical quality and meet the design and use demands, a reasonable gating system and a moderate shell process were used.
Influences of W and Al on the Microstructure and Stress-Rupture Property of Re-Free Ni-Based Single Crystal Superalloys
Authors: Chen Jing Yang , Li Qing , Zhang Ming Jun , Tang Xin , Xiao Cheng Bo
Published: June 2017

The influence of W and Al on the solidus and liquidus temperatures, microstructure and stress-rupture property at 980 °C/250 MPa was investigated in three Re-free experimental Ni-based single crystal superalloys. The results indicated that the solidus temperature increased for 14.0 °C and 9.8 °C by adding 0.84 wt.% W only and adding 0.45 wt.% Al and 0.44 wt.% W to the base alloy, respectively. The γ′ morphology changed from nearly cuboidal in the base alloy to cuboidal by adding 0.45 wt.% Al and 0.44 wt.% W. The volume fraction of γ′ precipitates increased, while the γ channel width decreased after adding Al and W. The additions of Al and W improved the stress-rupture life at 980 °C/250 MPa because of higher γ′ volume fraction, narrower γ matrix channel and more complete rafting structure.
Characteristics of Microscopic Inclusions and their Influence on Fatigue Crack Propagation in FGH96 Superalloy
Authors: Hou Jie , Dong Jian Xin
Published: June 2017

FGH96 superalloy has been used in aircraft engine turbine discs due to the superior damage tolerance. This work investigated the characteristics of microscopic inclusions and their influence on fatigue crack propagation in hot isostatic pressed and heat treated commercial FGH96 superalloy. Low cycle fatigue crack growth tests were conducted. Several kinds of microscopic inclusions were identified by optical microscope (OM), scanning electric microscope (SEM) and energy dispersive spectrometer (EDS). Microscopic inclusions and secondary cracks were analyzed near the main cracks. Combined with the finite element method (FEM) results, it can be proposed that the microscopic inclusions have no critical influence on fatigue crack propagation in the specimens.
Microstructure and Mechanical Properties of Ti62421S High Temperature Titanium Alloy with Different Heat Treatments
Authors: Song Xiao Yun , Wang Yong Ling , Zhang Wen Jing , Ye Wen Jun , Hui Song Xiao
Published: June 2017

In this paper, three different double annealing treatments were applied on the 3mm-thick Ti-6Al-2Sn-4Zr-1Mo-2Nb-0.2Si (Ti62421S) alloy plate. Optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tensile tests were used to investigate the microstructure and mechanical properties under different temperatures of Ti62421S alloy. The results show that the content of primary α phase (αp) decreases while transformed β structure (βt) increases with the increasing first-stage annealing temperature. After double annealing treatment, ordered α2 phase particles precipitate within αp and the size increases with first annealing temperature. This leads to that with increasing first annealing temperature, ultimate tensile strength (UTS) at 600~650°C increases while elongation decreases. After 1000°C/1h/AC+ 750°C/2h/AC annealing, Ti62421S alloy plate exhibits superior combination of mechanical properties at room and elevated temperatures.
Effect of Rare Earth Er on the Microstructure and Mechanical Properties of High Temperature Titanium Alloys
Authors: Li Bo Long , Wang Tong Bo , Han Peng , Wang Zhen Qiang , Nie Zuo-Ren
Published: June 2017

The microstructures and mechanical properties of the high temperature titanium alloys containing Er, i.e. Ti-6Al-2.5Sn-4Zr-0.3Mo-1Nb-0.35Si-xEr (x=0, 0.1, 0.3wt%), were investigated. Both the grain size and lamellar structure inside grains were significantly refined with the addition of Er in as-cast alloys. Lamellar and duplex microstructures were obtained after forging and heat treatment. Silicide precipitates were generated in the boundary of lamellar α phase after aging treatment. Meanwhile, a few α2 phase were precipitated in the alloys after aging treatment. After 600°C /100h thermal exposure, the α2 phases with a mean size of 7nm and spacing of 10 nm were precipitated homogeneously in α lamellar. The creep properties were significantly improved by the addition of rare earth Er due to the formation of the second phase containing Er, silicide and α2 phase.