Started in 1985 Semimonthly
ISSN 1005-0302
CN 21-1315/TG
Impact factor:6.155

The journal has been awarded the excellent periodical in China, and its articles are covered by SCI, EI, CA, SA, JST, RJ, CSA, MA, EMA, AIA etc., PASCAL web. ISI web of Science,SCOPUS.

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      28 May 2006, Volume 22 Issue 03 Previous Issue    Next Issue
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    Research Articles
    Antibacterial Effect of the Conducting Polyaniline
    Nanlin SHI, Xuemei GUO, Hemin JING, Jun GONG, Chao SUN, Ke YANG
    J. Mater. Sci. Technol., 2006, 22 (03): 289-290. 
    Abstract   HTML   PDF (200KB)
    Excellent antibacterial performance of polyaniline (PAni) against Escherichia coli and Gram-positive Staphylococcus aureus microorganisms has been demonstrated under both dark and visible light conditions. The electrostatic adherence between the PAni molecules and the bacteria may play a very important role for the antibacterial reaction of the PAni. As a result of our investigation, conducting PAni and its composites/blends are believed to be useful as a new type of antibacterial agent, self-clean as well as multifunctional material for improving the human health and living environment.
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    Improvement of Joint Strength of SiCp/Al Metal Matrix Composite in Transient Liquid Phase Bonding Using Cu/Ni/Cu Film Interlayer
    Rongfa CHEN, Dunwen ZUO, Min WANG
    J. Mater. Sci. Technol., 2006, 22 (03): 291-294. 
    Abstract   HTML   PDF (391KB)
    The compact oxide on the surface of SiCp/Al metal matrix composite (SiCp/Al MMC) greatly depends on the property of the joint. Inlaid sputtering target was applied to etch the oxide completely on the bonding surface of SiCp/Al MMC by plasma erosion. Cu/Ni/Cu film of 5 μm in thickness was prepared by magnetron sputtering method on the clean bonding surface in the same vacuum chamber, which was acted as an interlayer in transient liquid phase (TLP) bonding process. Compared with the same thickness of single Cu foil and Ni foil interlayer, the shear strength of 200 MPa was obtained using Cu/Ni/Cu film interlayer during TLP bonding, which was 89.7% that of base metal. In addition, homogenization of the bonding region and no particle segregation in interfacial region were found by analysis of the joint microstructure. Scanning electron microscopy (SEM) was used to observe the micrograph of the joint interface. The result shows that a homogenous microstructure of joint was achieved, which is similar with that of based metal.
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    Simulation of Fluid Flow, Heat Transfer and Micro-Segregation in Twin-roll Strip Casting of Stainless Steel
    Xiaoming ZHANG, Zhengyi JIANG, Xianghua LIU, Guodong WANG
    J. Mater. Sci. Technol., 2006, 22 (03): 295-300. 
    Abstract   HTML   PDF (1035KB)
    In twin-roll strip casting process, metal flow and temperature distribution in the molten pool directly affect the stability of the process and the quality of products. In this paper, a 3D coupled thermal-flow fenite element modeling (FEM) simulation for twin-roll strip casting of stainless steel was performed. Influences of the pouring temperature and casting speed on the temperature fields were obtained from the numerical simulation. The micro-segregation of the solutes during the strip casting process of stainless steel was also simulated. A developed micro-segregation model was used to calculate the micro-segregation of solutes in twin-roll casting of stainless steel. The relationship between the solidus fraction in solidification and temperature was given, which was used to determine the LIT (liquid impermeable temperature), ZST (zero strength temperature) and ZDT (zero ductility temperature) in the period of non-equilibrium solidification. The effect of temperature on the micro-segregation was discussed. According to the computational results, the solidification completion temperature in the twin-roll strip casting of stainless steel was then determined, which can provide a basis for controlling the location of solidification completion temperature and analyzing the crack of the casting strip.
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    The Inhibitive Effect of para-Amino Benzoic Acid and Its Polymer on Corrosion of Iron in 1 mol/L HCl Solution
    P.Manivel, G.Venkatachari
    J. Mater. Sci. Technol., 2006, 22 (03): 301-305. 
    Abstract   HTML   PDF (610KB)
    Poly p-aminobenzoic acid has been synthesized by chemical oxidation method. The inhibitive effect of poly p-aminobenzoic acid on iron in 1 mol/L HCl solution was investigated by polarization and electrochemical impedance spectroscopy and compared with that of monomer p-aminobenzoic acid. The effectiveness of poly p-aminobenzoic acid is very high in comparison with that of monomer. The results show that both cathodic and anodic processes were suppressed by p-aminobenzoic acid and poly p-aminobenzoic acid of iron dissolution in 1 mol/L HCl by their adsorption on the iron surface. The inhibition efficiency of both p-aminobenzoic acid and poly p-aminobenzoic acid were found to increase with the inhibitor concentrations. Ultraviolet (UV) reflectance studies of the iron surface after exposure to inhibitor acid show that poly p-aminobenzoic acid is strongly adsorbed on iron surface.
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    Evolution of Pore Size Distribution and Mean Pore Sizein Lotus-type Porous Magnesium Fabricated with Gasar Process
    Yuan LIU, Yanxiang LI, Huawei ZHANG, Jiang WAN
    J. Mater. Sci. Technol., 2006, 22 (03): 306-310. 
    Abstract   HTML   PDF (1694KB)
    The effect of gas pressures on the mean pore size, the porosity and the pore size distribution of lotus-type porous magnesium fabricated with Gasar process were investigated. The theoretical analysis and the experimental results all indicate that there exists an optimal ratio of the partial pressures of hydrogen pH2 to argon pAr for producing lotus-type structures with narrower pore size distribution and smaller pore size. The effect of solidification mode on the pore size distribution and pore size was also discussed.
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    Microstructure Evolution during Solidification of AZ91D Magnesium Alloy in Semisolid
    Wuxiao WANG, Bailing JIANG, Sen YUAN, Wanqi JIE, Guangyu YANG
    J. Mater. Sci. Technol., 2006, 22 (03): 311-314. 
    Abstract   HTML   PDF (314KB)
    The liquid quenching method was adopted to study the solidification morphology and microstructure of AZ91D Mg alloy in semisolid. The results indicate that cooling rate has important effects upon the solidification structures. Under the cooling rate of liquid quenching, primary α-phase grows first by attaching on the original α grains, or independent nucleation and growth. The high cooling rate makes primary α-phase grow in "rags" or dendrite shape. Eutectic solidification is carried out in terms of both dissociated growth and symbiotic growth. The dissociated growth forms rough and large β-phase at grain boundaries, while symbiotic growth forms eutectic of laminar structure. The small liquid pool inside the original α-phase solidifies basically in the same way as that of intergranular liquid, but owing to less amount of liquid phase, the eutectic solidification is mainly carried out in the dissociated pattern.
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    Microscopic Phase-field Simulation of Competition Mechanism Between L12 and D022 Structure in Ni-Cr-Al Alloy
    Zhong CHU, Zheng CHEN, Yongxin WANG, Yanli LU, Yongsheng LI
    J. Mater. Sci. Technol., 2006, 22 (03): 315-320. 
    Abstract   HTML   PDF (1286KB)
    Simulations are performed on temporal evolution of atom morphology and ordering parameters of Ni-14.5 Cr-16.5 Al alloy during early precipitation process at different temperatures based on microscopic phase-field theory; the relationship between precipitation sequence and mechanism of L12 and D022 structure and precipitation temperature are illuminated. The nonstoichiometric ordered L12 phases appear first with congruent ordering+spinodal decomposition mechanism which is then followed by precipitation of D022 phases at ordering domain boundaries of L12 phases by spinodal decomposition mechanism at 1073 K and 1223 K. The nonstoichiometric L12 phases transform to stoichiometric ordering phases gradually. The incubation period of L12 and D022 phases is shorter at 1073 K than that 1223 K, and growth speed is higher at 1073 K. At 1373 K, L12 and D022 phases appear simultaneously by non-classical nucleation and growth mechanism. After that the particles of D022 phases diminish and disappear gradually; L12 phases grow and single L12 phases are remained at last.
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    Effect of Brownian Coagulation on the Liquid-liquid Decomposition in Gas-atomized Alloy Drops
    Jiuzhou ZHAO, Lingling GAO, Jie HE, L.Ratke
    J. Mater. Sci. Technol., 2006, 22 (03): 321-323. 
    Abstract   HTML   PDF (263KB)
    Modeling and simulation have been carried out for Al-Pb alloys to investigate the Brownian coagulation effect on the microstructure development in a gas-atomized drop during the liquid-liquid decomposition. The results indicate that Brownian coagulation has a weak effect on the nucleation and a relatively strong effect on coarsening the minority phase droplets. The influence of Brownian coagulation on the liquid-liquid decomposition decreases with the increase in the diameter (or the decrease in the cooling rate) of the atomized drop.
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    Influence of Deposition Conditions on the Crystal Structure of MoS2 Coating
    Jihui WANG, Yang XIA, E.Wieers, L.M.Stals, X.Zhang, J.P.Celis
    J. Mater. Sci. Technol., 2006, 22 (03): 324-328. 
    Abstract   HTML   PDF (481KB)
    MoS2 coatings were prepared using an unbalanced bipolar pulsed DC (direct current) magnetron sputtering apparatus under different targets, cathode current densities, power modes and bias voltages. The morphology, structure and growth characteristics of MoS2 coatings were observed and identified respectively by scanning electron microscopy, X-ray diffractometry and mass spectrometry. The results show that MoS2 coatings evolve with the (002) basal plane parallel to the surface by using cold pressed target with lower density, lower cathodic current density, bipolar pulse DC power and minus bias voltage, whereas the coatings deposited under hot pressed target, higher cathodic current density, simple DC power and positive bias voltage have the (002) basal plane perpendicular to the surface. The influence of deposition conditions on the crystal structure of MoS2 coating is implemented by altering its growth rate and the energy of sputtering-deposition particles.
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    Preparation of Fe3O4 Film by in-situ Oxidative Hydrolysis on Chitosan
    Suwei YAO, Zhaohui ZHAO, Weiguo ZHANG, Hongzhi WANG
    J. Mater. Sci. Technol., 2006, 22 (03): 329-332. 
    Abstract   HTML   PDF (531KB)
    The Fe3O4 films were prepared by in-situ oxidative hydrolysis on chitosan. The structures and characteristics of the prepared Fe3O4 films were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), atom force microscopy (AFM), vibrating sample magnetometry (VSM) and thermogravimetric-differential thermal analysis (TG-DTA). The results show that, (1) the as-synthesized Fe3O4 films are pure Fe3O4 with cubic inverse spinel structure; (2) the network structured film can be obtained at lower temperature, and the compact particle film at higher temperature; (3) the prepared Fe3O4 films are super-paramagnetic, and the saturation magnetization is improved with increasing the reaction temperature, which is 49.03 emu/g at 80℃; (4) the temperature of phase transformation from F Fe3O4 to α-Fe2O3 is about 495℃. Besides, the formation mechanism of Fe3O4 film was also proposed.
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    Comparison of ZnO Films Grown on before- and after-vapor Transport Equilibration (VTE) LiAlO2 Substrates by Pulsed Laser Deposition (PLD)
    Jun ZOU, Shengming ZHOU, Jun XU
    J. Mater. Sci. Technol., 2006, 22 (03): 333-335. 
    Abstract   HTML   PDF (1127KB)
    About Φ45 mm LiAlO2 single crystal was grown by Czochralski (Cz) technique. However, the full-width at half-maximum (FWHM) value was high to 116.9 arcsec. After three vapor transport equilibration (VTE) processes, we can obtain high-quality LiAlO2 slice with the FWHM value of 44.2 arcsec. ZnO films were fabricated on as-grown slices and after-VTE ones by pulsed laser deposition (PLD). It was found that ZnO films on the two slices have similar crystallinity, optical transmittance and optical band gap at room temperature. These results not only show that LAO substrate is suitable for ZnO growth, but also prove that the crystal quality of LAO substrate slightly affects the structural and optical properties of ZnO film.
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    Nanoscale Multilayered ZrAlN/ZrB2 Coatings Synthesized by Magnetron Sputtering
    Dejun LI
    J. Mater. Sci. Technol., 2006, 22 (03): 336-338. 
    Abstract   HTML   PDF (714KB)
    Multilayered ZrAlN/ZrB2 coatings containing alternating bilayer periods were synthesized by dc magnetron sputtering technique. The intensities of ZrN (111) or ZrN (200) textures in the structure of the nanolayers depended on the bilayer period as well as N2 gas partial pressure during deposition. Nanoindentation testing showed that hardness and internal stress of the nanolayers varied with the bilayer period and crystallographic orientation in the coatings. The hardness of the nanolayers with bilayer periods of 3~6 nm was enhanced (~27%) over the rule-of-mixture value. A low percent of N2 in processing gas was proved to be benefitial to the synthesis of high hard nanoscale multilayered coatings.
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    A Genetic Algorithm for Simultaneous Determination of Thin Films Thermal Transport Properties and Contact Resistance
    Zhengxing HUANG, Zhen'an TANG, Ziqiang XU, Haitao DING, Yuqin GU
    J. Mater. Sci. Technol., 2006, 22 (03): 339-341. 
    Abstract   HTML   PDF (514KB)
    A genetic algorithm (GA) was studied to simultaneously determine the thermal transport properties and the contact resistance of thin films deposited on a thick substrate. A pulsed photothermal reflectance (PPR) system was employed for the measurements. The GA was used to extract the thermal properties. Measurements were performed on SiO2 thin films of different thicknesses on silicon substrate. The results show that the GA accompanied with the PPR system is useful for the simultaneous determination of thermal properties of thin films on a substrate.
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    Cu Diffusion in Co/Cu/TiN Films for Cu Metallization
    Xiuhua CHEN, Xinghui WU, Jinzhong XIANG, Zhenlai ZHOU, Heyun ZHAO, Liqiang CHEN
    J. Mater. Sci. Technol., 2006, 22 (03): 342-344. 
    Abstract   HTML   PDF (583KB)
    Some information on how to use in-situ determined diffusion coefficient of Cu to make barrier layer of Cu metallization in ultra large scale integrations (ULSIs) was provided. Diffusion coefficients of Cu in Co at low temperature were determined to analyze Cu migration to Co surface layer. The diffusion depths were analyzed using X-ray photoelectron spectroscopy (XPS) depth profile to investigate the diffusion effect of Cu in Co at different temperatures. The possible pretreatment temperature and time of barrier layer can be predicted according to the diffusion coefficients of Cu in Co.
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    Evaluation of Young's Modulus and Residual Stress of NiFe Film by Microbridge Testing
    Zhimin ZHOU, Yong ZHOU, Mingjun WANG, Chunsheng YANG, Ji'an CHEN, Wen DING, Xiaoyu GAO, Taihua ZHANG
    J. Mater. Sci. Technol., 2006, 22 (03): 345-348. 
    Abstract   HTML   PDF (433KB)
    Microbridge testing was used to measure the Young's modulus and residual stress of metallic films. Samples of freestanding NiFe film microbridge were fabricated by microelectromechanical systems. Special ceramic shaft structure was designed to solve the problem of getting the load-deflection curve of NiFe film microbridge by the Nanoindenter XP system with normal Berkovich probe. Theoretical analysis of load-deflection curves of the microbridges was proposed to evaluate the Young's modulus and residual stress of the films simultaneously. The calculated results based on experimental measurements show that the average Young's modulus and residual stress for the electroplated NiFe films are 203.2 GPa and 333.0 MPa, respectively, while the Young's modulus measured by the Nano-hardness method is 209.6±11.8 GPa for the thick NiFe film with silicon substrate.
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    Comparative Study of LiMn2O4 Thin Films Heat-treated by Conventional and Rapid Thermal Annealing
    Xianming WU, Mingyou MA, Zhuobing XIAO, Zeqiang HE, Jianben LIU, Mingfei XU
    J. Mater. Sci. Technol., 2006, 22 (03): 349-352. 
    Abstract   HTML   PDF (572KB)
    Cathode material LiMn2O4 thin films were prepared by solution deposition followed by conventional thermal annealing (CTA) and rapid thermal annealing (RTA) using lithium acetate and manganese acetate as starting materials. The phase and surface morphology identification was done by X-ray diffraction and scanning electron microscopy. The electrochemical properties of the thin films were carried out by cyclic voltammetry, charge-discharge experiments, electrochemical impedance spectroscopy and potential step technique. The results show that both thin films are homogeneous and crack-free. Compared with the CTA derived thin films, the RTA derived ones with smaller grain size are more smooth and dense. The CTA and RTA derived LiMn2O4 thin films deliver the capacity of 34.5μAh/(cm2•\μm) and 38 μAh/(cm2•μm) and show the capacity loss of 0.050% and 0.037% per cycle after being cycled 100 times, respectively. The diffusion coefficient of lithium ion in the CTA derived LiMn2O4 thin-film electrode is 4.59×10-11 cm2/s, and that of lithium ion in the RTA derived one is 3.86×10-11 cm2/s.
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    Improvement of Optical Reactivity for Nano-TiO2 Film by Nitrogen ECR Plasma
    Yuying XIONG, Tao MA, Linghong KONG, Junfang CHEN, Xianqiu WU, Honghua YU, Zhenxi ZHANG
    J. Mater. Sci. Technol., 2006, 22 (03): 353-358. 
    Abstract   HTML   PDF (1432KB)
    Nitrogen ion was implanted into the nano-TiO2 film surfaces by electron cyclotron resonance (ECR) plasma modification to improve the optical reactivity in visible-light region for nano-TiO2. Diagnosing the N2 plasma by optical emission spectroscopy (OES) was applied to the process of plasma modification. X-ray photoelectron spectroscopy (XPS) was used for analysis of the binding of element after plasma modification. It is shown that the surface modification was caused by excitated N. The injecting of N2 and N2+ leads to the increase in the dissociative interstitial state N in the films. The doped N makes for TiO2-xNx appearing in the TiO2 films. TiO2-xNx forms the impurity energy state in the TiO2 energy band gap and reduces the energy band gap. This is the main reason leading to the red shift of absorption edge.
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    Effect of Welding Parameters on GTA Weld Shape for Pure Iron Plate under Ar-O2 Mixed Shielding
    Shanping LU, H.Fujii, K.Nogi
    J. Mater. Sci. Technol., 2006, 22 (03): 359-366. 
    Abstract   HTML   PDF (1409KB)
    Weld shape variation for different welding parameters is investigated on pure iron plate under gas tungsten arc (GTA) welding with argon-oxygen mixed shielding. Results showed that small addition of oxygen to the argon base shielding gas can effectively adjust the oxygen adsorption to the molten pool. An inward Marangoni convection occurs on the pool surface when the oxygen content in the weld pool is over the critical value, 80×10-6, for pure iron plate under Ar-0.3%O2 mixed shielding. Low oxygen content in the weld pool changes the inward Marangoni to an outward direction under the Ar-0.1%O2 shielding. The GTA weld shape depends to a large extent on the pattern and strength of the Marangoni convection on the pool surface, which is determined by the content of surface active element, oxygen, in the weld pool and the welding parameters. The strength of the Marangoni convection on the liquid pool is a product of the temperature coefficient of the surface tension (dσ/dT) and the temperature gradient (dT/dr) on the pool surface. Different welding parameters will change the temperature distribution and gradient on the pool surface, and therefore, affect the strength of Marangoni convection and the weld shape.
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    Effects of the Process Parameters on Austenitic Stainless Steel by TIG-Flux Welding
    Heryueh HUANG, Shengwen SHYU, Kuanghung TSENG, Changpin CHOU
    J. Mater. Sci. Technol., 2006, 22 (03): 367-374. 
    Abstract   HTML   PDF (1386KB)
    The effects of the process parameters of TIG (tungsten inset gas)-flux welding on the welds morphology, angular distortion, ferrite content and hot cracking in austenitic stainless steel were investigated. Autogenous TIG welding process was applied to the type 304 stainless steel through a thin layer of activating flux to produce a bead on plate welded joint. TiO2, SiO2, Fe2O3, Cr2O3, ZnO and MnO2 were used as the activating fluxes. The experimental results indicated that the TIG-flux welding can increase the weld depth/width ratio and reduce the HAZ (heat affected zone) range, and therefore the angular distortion of the weldment can be reduced. It was also found that the retained ferrite content within the TIG-flux welds is increased, and has a beneficial effect in reducing hot cracking tendency for stainless steels of the austenitic type weld metals. A plasma column constriction increases the current density at the anode spot and then a substantial increase in penetration of the TIG-flux welds can be obtained.
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    Microstructure and Property Relationships in Resistance Spot Weld between 7114 Interstitial Free Steel and 304 Austenitic Stainless Steel
    Ahmet Hasanba&#, o&#, lu, Ramazan Kaç, ar
    J. Mater. Sci. Technol., 2006, 22 (03): 375-381. 
    Abstract   HTML   PDF (988KB)
    Due to the differences in physical, chemical and mechanical properties of the base metals, the resistance spot welding of dissimilar materials is generally more challenging than that of similar materials. The influence of the primary welding parameters affecting the heat input such as peak current on the morphology, microhardness, and tensile shear load bearing capacity of dissimilar welds between 304 grades austenitic and 7114 grade interstitial free steel has been investigated in this study. The optimum welding parameters producing maximum joint strength were established at a peak current of 9 kA, where the electrode force is kept 6×10-5 Pa and weld time is kept constant 17 cycles, respectively. The primary cause of weakening the weldment is identified as the excessive grain growing region of heat affected zone (HAZ) in case of 7114 grade interstitial free steel.
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    Structure Character of M-A Constituent in CGHAZ of New Ultra-Low Carbon Bainitic Steel under Laser Welding Conditions
    Lin ZHAO, Wuzhu CHEN, Xudong ZHANG, Jiguo SHAN
    J. Mater. Sci. Technol., 2006, 22 (03): 382-386. 
    Abstract   HTML   PDF (2305KB)
    800 MPa grade new ultra-low carbon bainitic (NULCB) steel is the recently developed new generation steel. The microstructure in the coarse-grained heat-affected zone (CGHAZ) of NULCB steel under laser welding conditions was investigated by thermal simulation. The influence of the cooling time from 800℃ to 500℃, t8/5 (0.3~30 s), on the microstructure of the CGHAZ was discussed. The experimental results indicate that the microstructure of the CGHAZ is only the granular bainite which consists of bainitic ferrite (BF) lath and M-A constituent while t8/5 is 0.3~30 s. The M-A constituent consists of twinned martensite and residual austenite, and the change of the volume fraction of the residual austenite in the M-A constituent is very small when t8/5 is between 0.3 and 30 s. The morphology of the M-A constituent obviously changes with the variation of t8/5. As t8/5 increases, the average width, gross and shape parameter of the M-A constituent increase, while the line density of the M-A constituent decreases.
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    Relief of Residual Stresses in 800 MPa Grade High Strength Steel Weldments by Explosion Treatment and its Effect on Mechanical Properties
    Changzhong WU, Huaining CHEN, Jing CHEN, Quanhong LIN, Jianjun GUAN
    J. Mater. Sci. Technol., 2006, 22 (03): 387-391. 
    Abstract   HTML   PDF (581KB)
    The explosion treatment technique has been used in the relief of residual stresses in 800 MPa grade high strength steel manual welded joints. The residual stresses on surface and through thickness of the weldment were measured for both as-welded and explosion-treated sample, the mechanical properties of welded joints under different conditions were also tested. The effect of explosion treatment on the fracture toughness of materials with a residual defect was investigated by crack opening displacement (COD) test. The results show that explosion treatment can reduce not only the surface residual stress but also the residual stress through thickness in the welded joints. The effect of explosion treatment on the mechanical properties and a residual defect in welded joint were inconspicuous.
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    Interaction Kinetics between Sn-Pb Solder Droplet and Au/Ni/Cu Pad
    Fuquan LI, Chunqing WANG, Yanhong TIAN
    J. Mater. Sci. Technol., 2006, 22 (03): 392-396. 
    Abstract   HTML   PDF (6047KB)
    The interfacial phenomena of the Sn-Pb solder droplet on Au/Ni/Cu pad are investigated. A continuous AuSn2 and needle-like AuSn4 are formed at the interface after the liquid state reaction (soldering). The interfacial reaction between the solder and Au layer continues during solid state aging with AuSn4 breaking off from the interface and felling into the solder. The kinetics of Au layer dissolution and diffusion into the solder during soldering and aging is analyzed to elucidate intermetallic formation mechanism at the solder/Au pad interface. The concentration of Au near the solder/pad interface is identified to increase and reach the solubility limit during the period of liquid state reaction. During solid state reaction, the thickening of Au-Sn compound is mainly controlled by element diffusion.
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    Comparison between Top and Bottom NiO-pinning Spin Valves: Effect of Interfacial Roughness on Specular Reflection
    Liang SUN, Jun DU, Xiaoshan WU, Shiming ZHOU, Xixiang ZHANG, An HU
    J. Mater. Sci. Technol., 2006, 22 (03): 397-400. 
    Abstract   HTML   PDF (375KB)
    Top and bottom NiO-pinning spin valves of Si/Ta/NiO/Co/Cu/Co/Ta and Si/Ta/Co/Cu/Co/NiO/Ta were prepared by magnetron sputtering, and X-ray diffraction and giant magnetoresistance (GMR) ratio were measured in the temperature range from 5 to 300 K. For the bottom spin valve, the interfacial roughness at NiO/Co is much smaller than that of Co/NiO in the top one. The Co/Cu and Cu/Co interfaces have the same roughness in the bottom and the top spin valves. NiO, Co, and Cu layers have (111) preferred orientations in the top one and random orientations in the bottom one. The GMR ratio of the bottom spin valve is larger than that of the top one at all temperatures and their difference increases with decreasing temperature.
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    Self-adjustment of Carrying Capacity of Concrete Embedded with CFRC
    Wu YAO
    J. Mater. Sci. Technol., 2006, 22 (03): 401-403. 
    Abstract   HTML   PDF (320KB)
    By heating up the embedded carbon fiber reinforced cement based material (CFRC), the carrying capacity and deformation of concrete member could be adjusted. The relationship between temperature difference and expansion strain of CFRC was demonstrated, and the temperature-deformation-load effect of concrete embedded with CFRC was studied. Heating the CFRC up to different temperatures resulted in different degree of inner pre-stress in concrete. Thus, the load capacity of concrete could be regulated owing to counteracting the pre-stress.
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    Fibre Optic Protection System for Concrete Structures
    J.S.Leng, A.Hameed, R.A.Barnes, G.C.Mays, G.F.Fern, o
    J. Mater. Sci. Technol., 2006, 22 (03): 404-410. 
    Abstract   HTML   PDF (1645KB)
    The design concepts, modelling and implementation of various fibre optic sensor protection systems for development in concrete structures were investigated. Design concepts and on-site requirements for surface-mounted and embedded optical fibre sensor in concrete were addressed. Finite element (FE) modelling of selected sensor protection systems in strain-transfer efficiency from the structure to the sensing region was also studied. And experimental validation of specified sensor protection system was reported. Results obtained indicate that the protection system for the sensors performs adequately in concrete environment and there is very good correlation between results obtained by the protected fibre optic sensors and conventional electrical resistance strain gauges.
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    Thermal analysis of glasses in TeO2-BaF2-LaF3 systems
    Dongbing HE, Junjie ZHANG, Zhongchao DUAN, Shixun DAI, Lili HU
    J. Mater. Sci. Technol., 2006, 22 (03): 411-413. 
    Abstract   HTML   PDF (199KB)
    Divalent metal fluorides MF2 (M=Sr, Mg, Ca) in oxyfluoride tellurite glasses TeO2-BaF2-LaF3 were synthesized. The densities, refractive indices and characteristic temperatures of synthesized glasses were measured. The influence of divalent metal fluorides MF2 (M =Sr, Mg, Ca) on the thermal stability of oxyfluoride tellurite glasses TeO2-BaF2-LaF3 were studied. Results show that the replacement of BaF2 by SrF2 and MgF2 can enhance the thermal stability against crystallization of the glass. A glass system with good thermal stability was produced, which could be a potential candidate for the host materials of the fiber devices.
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    On-line Monitoring of Epoxy Resin Exposed to Acid Solution
    Yuyan LIU, M.Kubouchi, H.Sembokuya, K.Tsuda, T.Tomiyama
    J. Mater. Sci. Technol., 2006, 22 (03): 414-418. 
    Abstract   HTML   PDF (469KB)
    In this study, a new on-line health monitoring technology for the determination of the penetration of environment solution into epoxy resin was pursued. A corrosion sensor including plastic optical fiber and pH indicator was fabricated. The color-change layer of this sensor appeared after immersion in sulfuric acid solution, which could be examined by using optical fiber and spectrophotometer. The results showed that the penetration of sulfuric acid was detected by adding bromophenol blue (BPB) in the corrosion sensor. This system could be applied to on-line health monitoring of chemical equipment structures.
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    Effect of Different Amounts of Graphite on the Sintering and Transverse Rupture Properties of Powder Metal Parts
    Mustafa Boz, Adem Kurt
    J. Mater. Sci. Technol., 2006, 22 (03): 419-422. 
    Abstract   HTML   PDF (1377KB)
    Iron powders were mixed with graphite powders by 1~15 wt pct to produce block samples using powder metallurgy technique. The powders were blended in a three dimensional blender for 20 min and compacted in a die under 500 MPa by using a one directional press. Sinterability and mechanical properties of the samples with different carbon content were investigated. Sintering process was carried out on a belt furnace with flame curtain in dissociated ammonia atmosphere. Block samples produced were suitable for ASTM B-312 transverse rupture strength test apparatus and were tested with 0.050 kN/s velocity in a press under 100 g load. It was found that graphite amount up to 2 wt pct increased the contact area of particles and acted as a lubricant to affect the sintering behaviour positively. The results indicated that the samples containing up to 5 wt pct showed good sintering behaviour and also good hardness due to an increase in pearlite amount. However, the samples containing higher amount of graphite (more than 5 wt pct) affected the sintering behaviour negatively due to the settlement of free graphite around the Fe powders, which resulted in a decrease in the hardness and transverse rupture strength.
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    Technology of Iron Carbide Synthesis
    M. Bahgat
    J. Mater. Sci. Technol., 2006, 22 (03): 423-432. 
    Abstract   HTML   PDF (1398KB)
    Iron carbides are very promising metallurgical products and can be used for steelmaking process, where it plays as an alternative raw material with significant economic advantages. Also it has many other applications, e.g. catalysts, magnets, sensors. The present review investigates the different properties and uses of the iron carbides. The commercial production and the different varieties for the iron carbides synthesis (gaseous carburization, mechanochemical synthesis, laser pyrolysis, plasma pyrolysis, chemical vapor deposition and ion implantation) were reviewed. Also the effect of different factors on the carburization process like gas composition, raw material, temperature, reaction time, catalyst presence and sulfur addition was indicated.
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