WANG Xu-dong, YI Zhong, SHEN Zi-cai, GU Peng-fei. Proton Radiation Damage in ZnO-pigmented White Paints and Optical Degradation Mechanisms[J]. Journal of Materials Engineering, 2013, 0(5): 1-5.
S781 white paints were irradiated with 150-keV protons in a simulated space environment, in order to elucidate more definitely the irradiation damage and optical degradation mechanisms for ZnO-pigmented white paints. After proton irradiations, the degradation in spectral reflectance and solar absorptance was measured in situ. The interaction between the protons and S781 white paints, and the irradiation-induced defects, were also studied through simulations and photoluminescence. The results show that the zinc vacancies in the 1-charge state are due to the ionization of the ZnO pigments, and are responsible for the b band absorption and optical degradation. Furthermore, this work also supports the first-principles results of considering zinc vacancies as the defects responsible for the green luminescence band from ZnO.
XING Wen-guo, MENG Xian-xing, FENG Wei-chun, ZHANG Chang-qiao. Drag Reduction Property of Mercapto-triazole on Natural Gas Pipeline[J]. Journal of Materials Engineering, 2013, 0(5): 6-10.
A new natural gas drag reduction agent 3-alkyl-4-amino-5-mercapto-triazole (AAMT) was synthesized. The drag reduction efficiency of AAMT was tested on the drag reduction test loop. The film-forming property of AAMT was studied by electrochemical characterization and SEM. The results show that AAMT adsorbs on the iron surface and smooth membrane is formed. The roughness of the gas pipeline is significantly improved. Under the condition of 4g/L AAMT and 1.5h, the maximum drag reduction efficiency is 10.03%.
GUAN Qi, LIU Hui-cong, ZHU Li-qun, LI Wei-ping, LIU Jian-zhong, YE Xu-bin. Scaling of 2524 Aluminum Alloy with Cladding in Simulated Fuel Tank Water Environment and Influence to Corrosion Behavior[J]. Journal of Materials Engineering, 2013, 0(5): 11-15,22.
Aluminum alloy corrosion and scaling is a universal problem during the use of fuel tank. The scaling and corrosion behavior of 2524 aluminum alloy with cladding were characterized and investigated in simulated fuel tank water environment by SEM, EDS and video microscope. Results indicate that the scaling behavior of 2524 aluminum alloy cladding in simulated fuel tank water environment can be divided into two states, the main component of scaling materials in the first state is Fe(OH)3 colloid, and in the second state is precipitation of hydroxide. With time, scaling area could change by rule of specific power function. In the first 24h, scaling materials accelerate the corrosion of aluminum alloy cladding; after 24h they prevent further corrosion of the material in simulated fuel tank water environment.
LANG Yu-ping, CHEN Hai-tao, WENG Yu-qing, QU Hua-peng. Applications of Thermo-Calc in Research of High Nitrogen Austenitic Stainless Steels[J]. Journal of Materials Engineering, 2013, 0(5): 16-22.
The Thermo-Calc software was used to calculate the influence of pressure factor and elements including C, Cr, Mn and Ni on the solubility of nitrogen, the phase transformation during solidification in high nitrogen austenitic stainless steel with 22%(mass fraction) Cr. The microstructures and precipitates of new designed high austenitic stainless steel were studied also. The results show that Cr increases mainly the solubility of nitrogen in liquid steel. With about 0.1%C the minimum solubility of nitrogen during higher solidification temperature is enhanced remarkably. Mn increases not only the solubility of nitrogen in liquid steel but also the minimum solubility of nitrogen during earlier solidification. With proper Mn the phase area of austenite is extended and more stably, also the "ferrite trap" can be avoided. With a little nickel less than 2% the minimum solubility of nitrogen during higher solidification temperature is enhanced and the temperature extension of δ phase presence is reduced, also to make sure full austenite in steel at room temperature. Melting under pressure is efficiently to increase the solubility of nitrogen. The main precipitates of new high austenitic stainless steel are Cr23C6 and Cr2N. To use thermodynamic calculation tools can be beneficial to research the melting, structure, heat treatment and hot working of high nitrogen austenitic stainless steels.
YANG Jin-long, LI Si-yu, YE Ling-ying, DENG Yun-lai. Effect of Li on Microstructures and Properties of Al-3.5Cu-1.5Mg Alloy[J]. Journal of Materials Engineering, 2013, 0(5): 23-27,32.
The effect of Li on microstructures and properties of Al-3.5Cu-1.5Mg alloy was studied by optical microscopy(OM),transmission electron microscopy(TEM),scanning electron microscopy (SEM),Vickers hardness(HV)and electronic tensile test respectively. The results show that the addition of 1% Li (mass fraction) translates the main precipitation phase S'(Al2CuMg) to S' (Al2CuMg) + δ'(Al3Li) in the alloy, which Cu/Mg atom ratio is about 1. Precipitate free zones (PFZs) are narrowed. Elastic modulus increases by 8GPa. The tensile strength is improved by 21MPa. However, the elongation of the alloy decreases from 20.3% to 15.8%. The form of fracture morphology is changed from ductile fracture to ductile/brittle mixed fracture.
FENG Rong-juan, LI Min, LIU Jia-xiang. Preparation of Small Size Au Colloid by Chemical Reduction[J]. Journal of Materials Engineering, 2013, 0(5): 28-32.
The colloidal gold nanoparticles were prepared by reducing chloroauric acid with NaBH4 in the presence of polyvinyl pyrrolidone (PVP). The influences of the amount of NaBH4 and PVP, reaction temperature and the order of adding NaBH4 on the morphology, particle size and dispersion of the synthesized gold nanoparticles are discussed. The gold nanoparticles’ morphology and particle size distribution were characterized by transmission electron microscopy and UV-Vis spectroscopy. The results show that the optimized processing parameters for preparing gold nanoparticles with an average diameter of 4.3nm were worked out, the molar ratio of NaBH4 to chloroauric acid is 3.75:1; the mass ratio of PVP to chloroauric acid is 1:1; the reaction temperature is 100℃; the NaBH4 is added after chloroauric acid. The ways of influencing factors were explained and the reasons were analyzed.
WANG Qing-juan, ZHANG Ping-ping, LUO Lei, DU Zhong-ze. Corrosion Behavior of Ultra-fine Grain Copper by Equal Channel Angular Pressing in 0.5mol/L NaCl Solution[J]. Journal of Materials Engineering, 2013, 0(5): 33-37,43.
The corrosion behavior of ultra-fine grain (UFG) copper bulk prepared by equal channel angular pressing (ECAP) was investigated in comparison with that in recrystallized coarse grain (CG) copper in 0.5mol/L NaCl solution by Tafel extrapolation method, E-t curve and immersion corrosion tests. Corrosion current was estimated by Tafel extrapolation method to examine the kinetics of corrosion in 0.5mol/L NaCl solution. The result shows that UFG copper exhibits a lower corrosion current and high self-corrosion potential in comparison with CG copper. UFG copper has higher corrosion resistance compared with CG copper. Corrosion damage on the surface of UFG copper is macroscopically rather smooth and uniform whereas localized corrosion of CG copper is very severe for obvious attacking at grain boundaries and selective corrosion of some grain by using electrochemical analysis and microscopic corrosion morphology.
MA Long-teng, WANG Li-min, HU Jin, LIU Zheng-dong, ZHANG Xiu-li. Hot Deformation Features of AISI403 Martensitic Stainless Steel[J]. Journal of Materials Engineering, 2013, 0(5): 38-43.
The hot compression experiment of AISI403 martensitic stainless steel was carried out by using Gleeble-1500D, and its flow stress was also investigated by means of microstructure analysis.The results show that the dynamic recrystallization of 403 steel occurs obviously at 950-1150℃ and strain rate from 0.01s-1 to 0.1s-1.The flow stress of 403 steel can be described well by a Zener-Hollomon parameter in the hyperbolic logarithm type equation.The regressed peak stress expression σP and the hot deformation activation energy Q of 403 steel during hot compression were concluded. Through the establishment of hot processing map, the best hot compression condition and the instability zones of flow behavior were acquired.
WANG Rui-fen, ZHANG Yin, XU Jian-yi, ZHANG Yang-huan. Effects of Cu-P Coatings on Electrochemical Properties of La0.75Mg0.25Ni3.2Co0.2Al0.1 Hydrogen Storage Alloy Electrode[J]. Journal of Materials Engineering, 2013, 0(5): 44-47,52.
A2B7-type La0.75Mg0.25Ni3.2Co0.2Al0.1 hydrogen storage alloy was coated by means of chemical plating. The effects of Cu coatings on the electrochemical properties of the hydrogen storage alloy were studied at different temperatures systematically. The results show that the cycling stability of the electrode is improved. The Cu coated powder electrode is better than bare electrode in exchange current density I0, high rate discharge ability and hydrogen diffusion coefficient D with increasing reaction temperature. The maximum discharge capacity of alloy electrodes decreases.
SHI Wei, TAN Yi, CAO Zuo-xuan. Process of Preparing Rigid Thermal Insulation Carbon Fiber Integrated Felt[J]. Journal of Materials Engineering, 2013, 0(5): 48-52.
With pre-oxidized fiber integrated felt prepared by relayed needle punching process as preform and thermosetting resin as precursor, impregnation-curing-carbonization of resin-graphitization process was employed to prepare rigid carbon fiber integrated felt used for thermal insulation. Effect of every process including needle punching parameters, carbonization temperature, solution concentration and curing pressure on density was studied. Microstructure of samples was studied by using SEM. The results show that high values of needle-punching parameters lead to high values of preform density, carbonization temperature has little influence on density, but much influence on carbon content. Also solution concentration and preform density have a certain influence on density. What is more, with increasing curing pressure, the density of samples increases.
SUI Jing, HU Na, DUAN Fang, SHI Dong-jian, CHEN Ming-qing. Preparation and Catalytic Property of Loaded Pd-M(Ag,Cu) Catalysts[J]. Journal of Materials Engineering, 2013, 0(5): 53-56.
Pd-M(Ag,Cu) bimetallic catalysts can be easily prepared via in situ reduction of the corresponding Pd2+, Ag+ and Cu2+ that the coordination interaction took place between the metal ions and amide of poly(N,N-diethylacrylamide) (PDEAm) using as-prepared PDEAm grafted poly(acrylonitrile/styrene) (PDEAm-g-PAN/PSt) microspheres as carrier. The ultrafine dispersed Pd-M (Ag,Cu) bimetallic nanoparticles were loaded on the surfaces of the PDEAm-g-PAN/PSt microspheres. The Pd-M bimetallic catalysts were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectrum (EDS) and thermo-gravimetric analysis (TGA). The results show that PDEAm-g-PAN/PSt microspheres have obvious flower-shape morphology,and Pd-M(Ag,Cu) nanoparticles are formed on the surface of polymer microspheres with the average particle size in about 10nm,and the catalytic efficiency of the Pd-M (Ag,Cu) is evaluated in hydrogenation reactions of 1-octylene. The catalytic efficiency of Pd-M bimetallic catalysts is higher than that of Pd/C, and the efficiency order is Pd-Cu>Pd-Ag>Pd/C.
QIAO Yin-hu, HAN Jiang, ZHANG Chun-yan, CHEN Jie-ping. Designing of Smart Composite Materials Wind Turbine Blade and Finite Element Analysis[J]. Journal of Materials Engineering, 2013, 0(5): 57-61.
With the increasing size of wind turbine blades, the need for more sophisticated load control techniques has induced the interest for aerodynamic control systems with build-in intelligence on the blades. New structural concepts have emerged where multifunctional materials, exhibiting a strong coupling between its mechanical response and its electrical behaviour, which work as sensors and actuators, are embedded or bonded to composite blades for high-performance structural applications. A finite element model of the smart blade for wind turbines is provided. Numerical analysis is performed by using finite element method, which is used to calculate the time response of the model. The displacement and stress response from the piezoelectric actuator are obtained to control the vibration, and compared with the fluid calculation results of the aerodynamic stress. By using this model, an active vibration method which effectively suppresses the vibrations of the smart blade is designed.
REN Bao-yi, LIU Zi-ru, GAO Yan-hui, ZHANG Xue-jun. Effect of SiO2 Coating Combined with Chemical Treatment by Phosphoric Acid on Oxidation Resistance of Ti-6Al-4V Alloy[J]. Journal of Materials Engineering, 2013, 0(5): 62-66,72.
The effects of phosphoric acid chemical treatment and composite SiO2 coating on oxidation resistance of Ti-6Al-4V alloy were investigated. Results show that, the average oxidation rate of the Ti-6Al-4V alloy treated by phosphoric acid decreases nearly by 75% in comparison with the blank samples at 600℃ after 24h oxidation in air. The oxidation rate of composite SiO2 coating sample reduces one order of magnitude in comparison with the blank sample oxidation for 100h at the same condition. The composite SiO2 coating has better anti-oxidation ability than phosphoric acid treatment. The compactness of the oxide scale of the composite SiO2 coating and the phosphoric acid treatment samples increases, and a good adhesion with the substrate is shown, the volume fractions of TiO2 in oxidation films reduce both phosphoric acid chemical treatment and composite SiO2 coating samples. The in-diffusion of O and out-diffusion of Ti are restrained because of the formation of TiP2O7 phase and deposit SiO2 coating.
ZHU Rong-hua, GANG Tie, WAN Chu-hao. In-situ Damage Monitoring of Aluminum Alloy Based on Acoustic Emission and Bispectrum Analysis[J]. Journal of Materials Engineering, 2013, 0(5): 67-72.
This work was performed on 7N01 aluminum alloy which used in the body of high-speed train and damage was monitored based on acoustic emission (AE) and digital image technology during three-point bending failure of 7N01 aluminum alloy, conventional AE parameters and bispectrum analysis were used to study the characteristic of AE signals during the crack initiation and unstable propagation of 7N01 aluminum alloy. The result shows that AE energy and centroid frequency (CF) were effective indicators to predict the crack initiation of 7N01 aluminum alloy. Bispectrum contour map of AE signals shows the coupling relationship of the two frequency components which makes it easy to identify different stages during three-point bending of 7N01 aluminum alloy. The digital images of damage evolution from monitoring the notch tip region of 7N01 sample verify the prediction of AE signals. The results indicate that AE technique provides the basis for predicting the initiation of micro-crack.
WANG Tao, CAO Wei, YAN Yue, LI Lei. Rheological Behavior of Polycarbonate Melt Under Squeeze Flow[J]. Journal of Materials Engineering, 2013, 0(5): 73-77.
As the existing rheometers are unable to characterize the stress-strain relation in squeeze process, a parrel plate squeeze flow apparatus with constant contact area mode was designed to characterize the rheological behaviour of the melt by measuring pressure and displacement of upper plate. Based on theoretical analysis and numerical calculation, the power law, PTT and XPP models were employed to find the most suitable constitutive equation for squeezing flow. The results show that squeeze stress of polycarbonate melt increases with growth of strain. When the temperature decreases and squeeze velocity increases, the stress-strain relation manifests three segmental distribution, wherever initial squeeze distance does not influence the stress-strain distribution mode and only has an effect on the squeeze stress. Viscoelastic constitutive model can predict the trend of change of squeeze stress, where predictive value of XPP model is more accurate to the experimental data.
WANG Zhong-gang, LU Zhai-jun, XIA Xi. Sensitivity Analysis of Out-of-plane Pre-compressed Aluminum Honeycomb to Drop First Peak Force[J]. Journal of Materials Engineering, 2013, 0(5): 78-82,88.
Numerical simulations of the pre-compressed aluminum honeycomb on sensitivity in dropping the first peak force were presented by resetting boundary conditions after refreshing the dynamic geometry and cell element information. The mechanical behavior of the aluminum honeycomb was observed before and after pre-compression compared with the quasi-static experiment, and necessarily the sensitivity of the first peak force on impact velocity and pre-compressed depth was analyzed. The results show that the honeycomb enters directly into the plateau stage without the first peak force under quasi-static loads; while impacting at a low velocity, there is a critical pre-compressed depth, and less than which a second peak force appears after some of stable compression, but when equal or larger than the critical depth, it appears at the initial time, thus, it is not tenable that the ideal periodic fold corresponding with the periodic peak force; to the pre-compressed honeycomb which has a second peak, the growing of the second peak is unobvious with the increasing of the impact velocity, on the contrary, a new initial peak force appears, which is even higher than the second one when the impact velocity higher than 20m/s; in general, both of the second peak force and the initial one are far smaller than the first peak force of the general honeycomb, and the property of the peak force is improved significantly after pre-compression. Series conclusions provide significant references for choosing and designing of cellular energy-absorbing materials.
GUO Hong-bao, WANG Bo, JIAO Gui-qiong, LIU Yong-sheng. Tensile Mechanical Behavior of Notched 2D-Cf/SiC Composites[J]. Journal of Materials Engineering, 2013, 0(5): 83-88.
The influence of notch types on tensile mechanical behavior of 2D-Cf/SiC composite laminates was studied by experimental and numerical methods. Specimens with symmetrical V shape, half round shape and hairline shape notches were tested respectively. The relationship between net stress and tensile deformation closed to the notches was obtained with extensometer. With strain gauges on the surface of notched specimens, the strain variation between notches was obtained. And strain concentration effect was also clearly expressed. In accordance with the law of strain variation, the damage evolution and failure process of the notched specimens were analyzed. By comparing results with that of standard specimens, the failure mechanism of the notched 2D-Cf/SiC composites was discussed, the main influencing factors to the tensile strength were also determined. Furthermore, by finite element analysis (FEA), the strain distribution of notched specimens was simulated. The results indicate that there exists asynchronous damage evolution and failure process on material between notches during tensile process, and the specimen’s net tensile strength decreases to some extent with different notch types; the FEA results have good agreement with experimental data.
JIA Hai-peng, SU Xun-jia, HOU Gen-liang, CAO Xiao-ping, BI Song, LIU Zhao-hui. Progress in Fabrication and Microwave Absorption Capacity of Graphene-based Magnetic Nanocomposites[J]. Journal of Materials Engineering, 2013, 0(5): 89-93,100.
After describing the novel configuration and tremendous properties of graphene, the fabrication methods of graphene-based magnetic nanocomposites are reviewed. Then microwave absorbing mechanisms of the nanocomposites are discussed. At last perspectives on the studies of the nanocomposites are provided. The further studies mainly include tailoring the micro-morphology and structure of nanocomposites, researching the interface interaction of nanocomposites, and investigating synergy of microwave absorption between graphene and magnetic nanoparticles.
DONG Shu-hua, WANG Cheng-guo, JIA Yu-xi, JIAO Xue-jian. Research Progress on Permeability of Fiber Composite Preforms with Structural Dependence[J]. Journal of Materials Engineering, 2013, 0(5): 94-100.
The permeability of fiber composite preforms, which is dependent on the multi-level structures of the preforms, is an important parameter influencing the resin flow during liquid composite molding. The research progress on the relationship between the permeability and the structure of the preforms was introduced from the viewpoint of the micro-level, meso-level and macro-level, respectively. The influence of various factors on the permeability of the preforms and the mathematical model were reviewed. The development tendency of the permeability research is prospected, which will help to reveal the defect formation mechanism of the composite products and further design the composite products and molding processes.
