FAN Jun-ling, GUO Xing-lin, WU Cheng-wei. Microstructures and Fracture Mechanisms of Fillet Welded Joints of FV520B Steel[J]. Journal of Materials Engineering, 2013, 0(7): 1-5,91.
The fatigue fracture surfaces of welded joints were observed and studied, and accordingly the fatigue mechanisms, governing fatigue failure of welded joints, were discussed. The microstructures on the base metal, the weld seam and the heat-affected zone of welded joints were investigated. It is concluded that the microstructures on the base metal are fine tempered martensite and dispersed secondary phase particles, whereas the ones on the weld seam are coarse lath martensite and few of secondary phase particles. The differences between their microstructures confirm the better mechanical properties of the base metal.
REN Bao-yi, WANG Si-lin, LIU Zi-ru, ZHANG Xue-jun. Activation Energy of Oxidation of Ti2AlNb Alloy Deposited SiO2 Coating[J]. Journal of Materials Engineering, 2013, 0(7): 6-10.
Amorphous silica coating was deposited on a Ti2AlNb alloy by sol-gel method. The kinetic data of oxidation mass gain was measured for coated and blank samples at 800℃ and 900℃ in air, and the oxidation rate constants at different temperatures were determined by the relevant linear fitting. According to Arrhenius relation of the oxidation rate constants, the activation energy of oxidation was derived for these samples at 800℃ and 900℃. It is found that the oxidation rate constant of coated sample is lower than the blank one and the value of activation energy of oxidation of coated sample is higher than the blank sample.
LIN Xue-dong, LIU Chang-ming, HUANG Xiao-yu. Microstructures and Properties of Al-16Si-6Ti Composites Tube Reinforced with In-situ Primary Ti(AlSi)2 Particles Fabricated by Centrifugal Casting[J]. Journal of Materials Engineering, 2013, 0(7): 11-15,23.
The microstructures of the Al-16Si-6Ti composites tube fabricated by centrifugal casting were observed and analyzed by SEM, EDS and OM. The hardness and wear resistance, and the particle volume fraction of the tube were measured by using Image Tool and calculated, respectively. The results show that the tube consists of an outer layer segregating many primary Ti(AlSi)2 particles, the middle layer of the Al matrix having no particles and the inner layer containing some primary Si particles. The hardness decreases gradually firstly and then increases slightly from outer wall to inner wall on the cross section of the tube along the radial direction, which conforms to the variation tendency of the particle volume fraction. In the centrifugal field, the primary Ti(AlSi)2 particles migrate and assemble in the outer layer of the tube to form the Al-16Si-6Ti composites.
PEI Xiao-yuan, LI Jia-lu, HE Yu-qiang. Effects of Fiber Orientation on Modal Experimental Analysis of Three-dimension and Four-direction Braided Composites and Laminated Composites[J]. Journal of Materials Engineering, 2013, 0(7): 16-23.
The dynamic mechanical properties of carbon fiber three-dimension and four-direction braided composites and laminated composites with different fiber orientation angle were studied. The effect of different fiber orientation angle on the vibration properties of carbon fiber three-dimension and four-direction braided composites and laminated composites were analyzed. The experimental results show that with the fiber orientation angle increasing, the natural frequency of composites decrease and loss factor increase. The three-dimension and four-direction braided composites has larger natural frequency and specific stiffness,however with the same order, the loss factor of the laminated composites is larger.
XIAO Zhi-yuan, YANG Mu-qing, LI Zheng-neng. Working Characteristic Affecting Factors of Transformable Airships’ Solar Cell Array[J]. Journal of Materials Engineering, 2013, 0(7): 24-28,34.
Solar cell array is the main power system of near-space transformable airship, which generally determines the performance of airship. According to the features of transformable airships, the geometry model and sun radiation model of solar cell array was established when transformable airships operate in the cruise condition. Applying models, the solar radiation intensity and power received by solar cell array was calculated based on the changes of solar radiation and airships’ flight altitude. Results show that the power at noontide is 3-4 times as much as that at morning and nightfall. When solar elevation angle is low, power collection is affected by the flight angle of airship. Season is a main factor that influences the intensity distribution and power at noon. Latitude influences the total power of solar cell array. It is good for power collection to place the solar cells on the top of the airship.
ZHAN Li-chun, CHI Hong-xiao, MA Dang-shen, FU Rui, JIANG Ye-hua. The As-cast Microstructure of ESR-CDS M2 High Speed Steel[J]. Journal of Materials Engineering, 2013, 0(7): 29-34.
The ESR and ESR-CDS casting microstructure of the M2 high speed steel was studied.The results show that the casting’ edge is dendrite and appears three times dendrite with ESR,and the structure of heart are coarse equiaxed grains,between which is network carbide,and the segregation of ingot is more serious,the matrix and carbide transition region is loose and rough,and the fine crack is found of some part of the substrate with the deep etching.However, the structure of casting’edge and heart are small dentrite,and there are more "discontinuous composite regular type"carbide,the structure is more uniform,the transition zone of carbide and matrix is smooth with the depth of corrosion.
YU Li-hua, YUAN Cai-yun, XU Jun-hua. Microstructures and Mechanical Properties of Magnetron Sputtered NbSiN Composite Films[J]. Journal of Materials Engineering, 2013, 0(7): 35-39.
NbSiN nano-composite films with different Si content were fabricated by magnetron sputtering technique. The composition, microstructure, mechanical and tribological properties of the films were investigated by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), nano-indentation, and high-temperature tribo-meter. The results show that the coatings exhibit fcc NbN structure with a (200) preferential orientation. With increasing of Si content, the hardness of NbSiN composite films increases gradually to a maximum value of 32.1GPa at Si content of 20.29% atom fraction and then decreases. The friction coefficients of NbSiN coatings range from 0.60 to 0.68 with different Si content at room-temperature, however decrease from 0.57 to 0.42 at 650℃. The mean friction coefficients at high temperature are lower than those at room temperature, which is attributed to the formation of oxides at high temperature.
YUAN Yuan, LI Fu-ping, SUN Xia-rong. Analysis on Fatigue Behavior of Vulcanized Natural Rubber Under Constrained Condition[J]. Journal of Materials Engineering, 2013, 0(7): 40-43,49.
The shear fatigue behavior of vulcanized natural rubber (NR) under constrained condition was investigated by Gel Permeation Chromatography(GPC), Attentuated Total Reflectance-Fourier Transform InfraRed(ATR-FTIR) spectroscopy, and Gas Chromatography-Mass Spectrometry(GC-MS). The results showed that in the shear fatigue process molecular chains were first broken under one-dimensional compression load, and then oxygen aging occurred.At the same time, some of the low-molecular mass degradation products and free state fillers migrated and agglomerated at the stress concentration regions.
ZHANG Yan-fei, LAN Yan-hua, FU Yi-zheng, ZHAO Gui-zhe, HU Guo-sheng. Molecular and Mesoscopic Dynamics Properties of PA6/POE Blends[J]. Journal of Materials Engineering, 2013, 0(7): 44-49.
PA6 and POE were simulated by molecular dynamics (MD) and mesoscopic dynamics (MesoDyn) for predicting properties of PA6/POE blends such as the compatibility, the glass transition temperature (Tg), mechanical properties and binding energy of PA6/POE blends. Results show that the Tg has been determined by the slope of the V-T simulation data, and the Tg of PA6/POE are respectively corresponding to Tg of PA6 and POE, which are incompatible system. MesoDyn simulation method was used to simulate the mesoscopic phase separation behavior of PA6/POE. The order parameters computed for the blends can predict that the blends are incompatible systems. Therefore, the method used in this work is a useful tool to provide properties of a given polymer blends. In addition, it is a promising technique to help screen polymer formulations before experimental tests.
GUO Shi-rui, YAO Jian-hua, CHEN Zhi-jun, LOU Cheng-hua, WU Han-feng. Effects of Structure of Nozzle on Gas Atomization for Laser Cladding Alloy Powders[J]. Journal of Materials Engineering, 2013, 0(7): 50-53,60.
Focus on the question of producing specific powers for laser cladding by gas atomization, adjusted the ratio of powder material, compared to the original nozzle, the atomization experiments were carried on to produce nickel-based powder of laser cladding by improved supersonic nozzle. The results show that the gas-atomizing nozzle is an important factor in the process of gas atomization. With the improvement of structure of nozzle, the particle mean diameters, volume mean diameters and Sauter mean diameters decrease. In other words, the particle size decreases. Meanwhile, the powders have better fluidity, larger apparent density and efficient atomization efficiency, which meet the requirements of laser cladding.
TONG Chen, SU Xu-ping, LI Zhi, WANG Jian-hua, WU Chang-jun, PENG Hao-ping, XU Peng. Research on Hot-dipped Zn-6%Al-3%Mg Alloy Coatings Intermetallics Layer Growth[J]. Journal of Materials Engineering, 2013, 0(7): 54-60.
Zn-6%Al alloy and Zn-6%Al-3%Mg alloy coating was galvanized by hot-dip method in different immersion time to get intermetallics layer with different thickness. Samples were characterized by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) to investigate the interfacial reaction and phase composition of intermetallics layer. It is found that the hot-dip Zn-6%Al-3%Mg alloy coating intermetallics layer consisted of the Fe-Al-Zn intermetallics compound, the Fe-Al-Zn intermetallics layer inhibited formation of the brittleness Fe-Zn compound layer. The addition of Mg into the Zn-6%Al bath promotes the interface reaction and growth of the intermetallics layer and makes it dense. With the Mg addition, the trend of the diffusion path moving gradually to the line connecting with two diffusion component points was inhibited, and intermetallics layer would be dense. Meanwhile, the intermetallics layer becomes too stable to be eroded by the liquid zinc. The thickness of the coating increases with prolonging of dipping time. The growth of the coating in Zn-6%Al-3%Mg bath is controlled by diffusion.
SUN Jie, ZHAO Dan. Galvanic Corrosion Bahavior of Superalloy/NiAl Seal Coating[J]. Journal of Materials Engineering, 2013, 0(7): 61-65,72.
NiAl seal coating was prepared on the superalloy substrate by air plasma spraying method. The galvanic corrosion behavior in 5%(mass fraction) NaCl solution was investigated for the NiAl seal coating and superalloy substrate. The measurement methods, which consisted of scanning electron microscopy (SEM), polarization curve and open circuit potential, were used to character the morphology and the corrosion behavior of the coating. The results indicated that the galvanic current density was about 2.1356μA/cm2. The NiAl coating with more negative corrosion potential served as the couple’s anode and it had seriously corrosion, loosen and floccus corrosion products covered on the coating’s surface. In the as-sprayed NiAl seal coating, there existed many pores and oxides, and corrosion was easy to occur in the area lack of oxide coverage. While the oxides which on the edge of the coating were priority dissolved, and the corrosion products would block the pores and inhibit the corrosion process. The protection performance of the coating was weaken gradually with the extention of corrosion time.
GU He-gen, CAI Zhen-bing, YUE Wen, PENG Jin-fang, ZHU Min-hao. Torsional Fretting Wear of Sulfurized-nitrided Layers Prepared on Axle Steel[J]. Journal of Materials Engineering, 2013, 0(7): 66-72.
The sulfurized-nitrided layers were prepared on the surface of LZ50 steel by sulfurized-nitrided duplex processes. Base on the characterizations of the sulfurized-nitrided layers, the torsional fretting wear tests of the sulfurized-nitrided layers and LZ50 steel were carried out in dry condition under different torsional angular displacement amplitudes. The results indicated the sulfurized-nitrided layers were composed of ε-Fe2-3N,γ'-Fe4N, FeS and FeS2 phases. The fretting regimes of the sulfurized-nitrided layers were changed, i.e. the range of the mixed fretting regime was diminished, and the slip regime shifted to the direction of smaller angular displacement amplitude. The friction torques of the sulfurized-nitrided layers were lower than that of the substrate in the partial slip and slip regimes due to the support of the hard nitrided layer and the lubricating of the sulfide layer. Comparing with the substrate, the wear of material reduced greatly for the sulfurized-nitrided layers. The damage in the partial slip regime was slight, but in the mixed and slip regimes the damage mechanisms of the modified layer were mainly delamination, abrasive wear and oxidative wear.
ZHAO Hong-xia, HUANG Xu, WANG Bao, LEI Li-ming. Effect of Heat-treatment on the Microstructure and Thermal Stability Properties of Ti-35V-15Cr-0.15Si-0.05C Titanium Alloy[J]. Journal of Materials Engineering, 2013, 0(7): 73-77.
The thermal stability property and the microstructures of Ti-35V-15Cr-0.15Si-0.05C after solution and aging were studied. The solution temperature was 850℃ and 950℃ and the aging temperature was 600℃and 700℃ after solution at the temperature of 950℃.The results showed the α phase had not separated out obviously when the alloys heat treatment by solution, and the α phase separated out a great deal in boundary and in grains after aging, and separated out more after 100 hours explored at 540℃. The α phase were the main factor which affected the thermal stability. The continuous α phase in the boundary of grains leaded rapidly decreasing plasticity. The alloy heat treatment by 850℃solution could obtain good and thermal stability.
QIAO Hai-bin, LIU Lin, ZHAO Xin-bao, TANG Xin, ZHANG Jun, FU Heng-zhi, LI Xiang-hui, CAO La-mei. Thermodynamics Calculation and Analysis of Oxide Inclusion Formation in Single Crystal Superalloy DD6[J]. Journal of Materials Engineering, 2013, 0(7): 78-82,96.
Calculation and analysis on the thermodynamics conditions for the formation of oxide inclusion during the vacuum induction melting of Ni-based single crystal superalloy DD6 have been carried out by using Thermo-calc thermodynamics software and JMatPro analysis software. The results show that the main oxide inclusion is Al2O3. Under the thermodynamic equilibrium state, the value of oxygen activity during the melting and solidification stages is within (3.21-14.0)×10-7 and (1.63-4.89)×10-8. It will cause increasing oxygen in the molten liquid and the formation of Al2O3 inclusion by using CaO crucible when the vacuum level is 0.1Pa. In order to make the content of Al2O3 inclusion reduce to less than 10×10-6, it is necessary to control oxygen content below 4.709×10-6 before alloying treatment.
LONG Jian-ping, HAO Xiao-li, LIN Jin-hui. Preparation and Characterization of Fluoroapatite Particles via Microemulsion[J]. Journal of Materials Engineering, 2013, 0(7): 83-86.
Fluoroapatite particles are synthesized in the quaternary microemulsion system containing OP emulsifier, isooctane, decanol, calcium nitrate, potassium fluoride and diammonium phosphate. SEM, XRD, FT-IR and EDS are used to characterize the morphology and structure of the different resulted samples under different pH circumstance. The results indicate that under the weak base condition, fluoroapatite is more advantageous to synthesize, and the crystallization is much higher. The Ca/P of fluoroapatite obtained by pH=7.5 is about 1.62, approaching to the theoretical value (1.67).
SHEN Er-ming, LI Xiao-xin, WANG Zhi-hong, TENG Bai-qiu, LIU Jia. Hygrothermal Aging Analysis of Rubber Materials After Long-term Storage[J]. Journal of Materials Engineering, 2013, 0(7): 87-91.
After storage period of 1.5 years, then 0, 5, 10, 20 days and 60 days hygrothermal test were carried out for nitrile rubber, fluororubber and fluorosilicone rubber, the appearance, mass gain, Shore A hardness, tensile strength, elongation at break and set after break were investigated in the dry and wet conditions. The results show that different samples had distinct moisture absorbing performance. After storage and hygrothermal environment, the nitrile rubber less affected; the fluororubber absorbed a amount of moisture, but did not produce significant effects of aging on the hardness and the mechanical properties; the fluorosilicone rubber significant aged after the storage, and hygrothermal environment speeded up the aging process. The nitrile rubber and fluororubber suitable for storage in the hygrothermal environment.
LIU Qing-sheng, HE Wen, ZENG Fang-jin, XUE Ji-lai. Damage Properties of Carbon Cathodes Under Different Aluminium Electrolysis Time[J]. Journal of Materials Engineering, 2013, 0(7): 92-96.
Uniaxial compression experiments were conducted to obtain the stress-strain curves of carbon cathode samples under different aluminium electrolysis time, and the damage constitutive model of the carbon cathode was established. Experimental and theoretical results show that properties of the corroded carbon cathode, such as elastic modulus, peak strength and residual deformation, are degraded compared with the non-aluminium electrolysis ones, which are caused by the increasing of initial microscopical damage regions that random distributed in the carbon cathode. The uniaxial compression test of the carbon cathode was numerical simulated by the Realistic Failure Process Analysis software RFPA2D, and the simulation results match well with the theoretical and experimental ones. It is confirmed that the numerical simulation can be used effectively to represent the deformation and fracture process of carbon cathodes.
