LI Yan, LING Guoping, LIU Kezhao, CHEN Changan, ZHANG Guikai. Effects of Heat Treatments on Phase Structure of Electrodeposition Aluminum Coatings on Different Substrates[J]. Journal of Materials Engineering, 2010, 0(2): 1-5.
Effects of heat treatment on phase structure of electrodeposition aluminum coatings on different substrates was studied.The samples with dense aluminum coatings electrodeposited on Q235 mild steel,1Cr17 ferrite stainless steel and 201 austenitic stainless steel from acid AlCl3-EMIC(2:1) room temperature molten salts was heat treated at 670℃.The interface microscopic analysis was carried by EDS,SEM and XRD.The results show that interdiffusion happens and the alloy layers form at the interface between aluminum coatings and the substrates after heat treated.Alloy layer grows like tongue to the substrate of Q235 which is flat on the substrate of 1Cr17 and 201 steel.The phases are FeAl and Fe2Al5 phases,mainly Fe2Al5 on the internal and external alloy layers of Q235;but there are Fe2Al5 and FeAl3 phases containing Cr on the alloy layers of the 1Cr17 steel;there exists pure Al layer on the alloy layers of 201 steel heat treated after short time,the phases are mainly Fe2Al5 and FeAl3 phases containing Cr,Ni,Mn after heat treated for 30min,and there are a little FeAl2 and FeAl phases.
YAN Chunyan, LI Wushen, BAI Shiwu, XUE Zhenkui. Study on Phase Transformation in Welding Heat Affected Zone of 9Ni Steel[J]. Journal of Materials Engineering, 2010, 0(2): 6-9.
Thermal simulation with Gleeble was performed to investigate phase transformation in the heat affected zone of 9Ni steel for liquefied natural gas storage tanks.Results showed that bainite and martensite might be obtained after experiencing heat cycles.With low cooling rates,a mainly bainitic microstructure(including granular bainite and upper bainite) developed after experiencing heat cycles.When cooling rate increased,granular bainite was more likely to generate than upper bainite.With high cooling rates,a mainly martensitic microstructure developed after experiencing heat cycles.
LI Ping, TAN Jialong, HAO Jingyan, ZHOU Hongwei. Ultrasonic Non-destructive Testing the Coking Layer in Inner Surface of Heating Pipe[J]. Journal of Materials Engineering, 2010, 0(2): 10-12.
Based on the rule of ultrasonic wave propagating in the multilayered medium,the feasibility of non-destructive evaluating the coking layer in inner surface of heating pipe by ultrasonic technology was discussed.It is found that the echo signals have remarkable differences among coking layers with various thickness.Altitude,periodicity and distortion degree of echo can be influenced by the thickness of coking layer.With the increase of thickness,echo altitude dropped,periodicity reduced and the distortion became more serious.Hence,it is feasible to evaluate the coking layer using the ultrasonic technology.
ZHANG Xiaofan, XING Li, YANG Chenggang, KE Liming. Effect of the Lack of Penetration on the Conductivity of LY12 Aluminum Alloy Friction Stir Welds[J]. Journal of Materials Engineering, 2010, 0(2): 13-16.
The eddy current conductivity gauge was used to measure the conductivity distribution of the weld cross section and the conductivity at the original weld line with different depth of the lack of penetration(LOP) defect in the friction stir weld of LY12 aluminum alloy.The results show that,the conductivity in the nugget zone is higher than the base metal,and there is a transient zone between these two areas.The variation of conductivity is related with the microstructure in the weld.The depth of the LOP defect affects the distribution of the conductivity in the weld.If the depth of the LOP is small,the conductivity of the welds is almost same as the welds without any defect.On the contrary,If the depth of the LOP is big,the conductivity at the centre of the weld decreased dramatically,and the deeper the defect is,the lower conductivity is.
AN Haoyuan, ZHAN Maosheng, WANG Kai. Synthesis and Performance of Fluorene-containing Copolyimide Adhesives[J]. Journal of Materials Engineering, 2010, 0(2): 17-20.
The fluorene-containing copolyimide(CPI) films were synthesized by polycondensation of 4,4'-oxydiphthalicanhydride(ODPA),9,9'-bis(4-aminophenyl)fluorene(BAFL) and another diamine 3,4'-diaminodiphenyl ether(3,4'-ODA),4,4'-diaminodiphenyl ether(4,4'-ODA),1,3-bis(4-aminophenoxy)benzene(1,3,4-APB) or 1,4-bis(4'-aminophenoxy)benzene(1,4,4'-APB) through two-step method.The CPI films were characterized by FT-IR,DMTA,TGA and tensile tests.The partially imidized CPI films were adhered to stainless steel plates for preparing single lap joints.The results showed that fluorene-containing CPI films possessed good mechanical and thermal properties.The lap shear strength(LSS) of CPI film synthesized from BAFL,3,4'-ODA and ODPA were 19.2MPa and 13.4MPa at room temperature and 250℃ respectively.
HE Gang. The Changes of MK101 Catalyst Structure and Activity Leaded by Heat[J]. Journal of Materials Engineering, 2010, 0(2): 21-24.
The chemical analysis,electron spectroscopy,X-ray diffraction,absorption instrument and so on,be used to research MK101 methanol catalyst structure and activity.The results showed that: Laboratory catalyst heated to high temperatures can increase the grain size,decreased specific surface area 31%,increased average pore diameter 21%,decreased pore volume 22.2%;industrial catalyst after use also increased the grain size,decreased specific surface area 38.2%-56.4%,increased average pore diameter 21%,decreased pore volume 51.4%-57.9%.After Intense heat,both catalysts change in the same trends,the grain size and average pore diameter increase,the specific surface area and pore volume decrease,catalytic activity are reducing.After heat-resistant experiments in laboratory,the small-aperture of catalyst was little affected,the large aperture was high affected and generate more large holes.After the industrial use,the large aperture of catalyst was little affected,the small-aperture of catalyst was high affected,so that a large number of small holes become large,reduced the ratio of small holes,leaded to reduction and loss of catalytic activity.
LI Wenbin, PAN Qinglin, LIU Junsheng, LIANG Wenjie, LIU Xiaoyan, HE Yunbin. The Flow Behavior and Microstructural Evolution of Ultra-high Strength Aluminum Alloy Containing Sc Under Elevated Temperature Compression[J]. Journal of Materials Engineering, 2010, 0(2): 25-28,32.
The flow behavior of a new ultra-high strength aluminum alloy containing Sc was investigated with compression tests in temperature range 380-470℃ and strain rate range 0.001-10s-1 using Gleeble1500 system,and the associated microstructural evolutions were studied by way of OM and TEM.The results showed that the true stress-true strain curves exhibit a peak stress followed by a dynamic flow softening at small strains(ε<0.15),which can be represented by a Zener-Hollomon exponential equation with the hot deformation activation energy Q of 157.9kJ/mol.The substructure in the deformed specimens consists of very small amount and fine precipitates with equaixed polygonized subgrains in the elongated grains and developed serrations in the grain boundaries.The dynamic flow softening is attributed mainly to dynamic recovery(DRV) and dynamic recrystallization(DRX).
CHU Liqiu, CHEN Yu, SU Wenjuan, TAN Huimin, ZHAO Xinqi. Preparation and Characterization of Water-based Fe3O4 Magnetic Fluid Modified by STPP[J]. Journal of Materials Engineering, 2010, 0(2): 29-32.
The stable water-based magnetic fluid was prepared by surface modification of Fe3O4 magnetic nanoparticles with sodium tripolyphosphate(STPP).The magnetic fluid was characterized by FTIR,TG,TEM,XRD,XPS,VSM and zeta potential.The results show that Fe3O4 magnetic nanoparticles are coated by STPP in surface.Particle surface acquires a negative charge at pH value above 3.It is found that STPP/Fe3O4 magnetic nanoparticles are superparamagnetic with a specific saturation magnetization of 62.3 A·m2·kg-1.
LIU Yuanyong, ZHANG Xiaoyun, PEI Hezhong, LU Feng, GAO Jian. Research on the Properties of Stress Corrosion Crack for 7B04 Alloy[J]. Journal of Materials Engineering, 2010, 0(2): 33-36,41.
The susceptibility of 7B04 Aluminum alloy to Stress Corrosion Crack(SCC) was investigated using the Slow Strain Rate Test(SSRT).The effect of temperature,corrosion medium and the polarization were also analyzed.The results showed that the susceptibility of 7B04 aluminum alloy to SCC is enhanced with the growth of temperature;the higher causticity of solution,and the stronger of polarization.The microstructure was also observed by Scanning Electron Microscopy(SEM) after the SSRT.
XU Binshi, ZHANG Xiaodong, DONG Shiyun, DONG Hanshan, WANG Zhijian, YAN Shixing. Study on Wear Resistance of Duplex Surface Treatment with Laser Cladding and Active Screen Plasma[J]. Journal of Materials Engineering, 2010, 0(2): 37-41.
In order to study effects of laser cladding layer performance on wear resistance of active screen plasma treating nitride coating,two kinds of Fe-based alloy powders,Fe314 and Fe90,were adopted to laser clad on steel 45 substrate surface.And then the laser clads were duplex-treated by active screen plasma nitriding.Wear tests were carried out for the laser clads and duplex coatings with wear tester under dry sliding condition.Experimental results show that hardness of the Fe90 duplex coating was increased from 750HV of the Fe90 laser clad to 1350HV,and hardness of the Fe314 duplex coating was increased from 540HV of the Fe314 laser clad to 927HV.Under the same load(30N),wear resistance of the Fe90 duplex coating was 1.2 times of that of the Fe90 laser cladding layer.However,wear resistance of the Fe314 duplex coating was only 0.42 times of that of the Fe314 laser cladding layer.It can be found that the key problem for improving wear resistance of the duplex coating lies on reasonable combination of the laser cladding layer and active screen plasma treating nitride coating,the former should provide enough support for the latter.
WANG Yuan, ZHOU Fei, ZHANG Qingwen. Tribological Properties of Duplex Al2O3/CrNx Coatings[J]. Journal of Materials Engineering, 2010, 0(2): 42-46,51.
In order to improve tribological properties of aluminum alloy,duplex Al2O3/CrNx coatings were prepared on 2A12 aluminum alloy by micro-arc oxidation and reactive radio frequency magnetron sputtering technique.The phase structure,thickness,nano-hardness,tribological properties and scar's micro-morphologies of Al2O3 and duplex Al2O3/CrNx coatings were respectively investigated by X-ray diffraction,MINITEST1100 equipment,nano-indenter,tribo-meters,non-contact surface profilers and scanning electron microscope.The results show: The porous alumina ceramic coating with 32μm thickness is mainly composed of α-Al2O3 and γ-Al2O3 phases,the outer CrNx coating with 1.2μm thickness is mainly composed of Cr,Cr2N and CrN phases.With an increase in normal load,the friction coefficients and specific wear rates of both coatings increase.Moreover,under the same experimental condition,the friction coefficient and specific wear rate of duplex coating are smaller than those of Al2O3 coating,which indicate friction and wear properties of the Al2O3 coating are improved and the lifetime of counterpart is prolonged with deposition of CrNx film on the Al2O3 coating.
WANG Yaohua, CHEN Guangchao, HE Qi, LI Chengming, L� Fanxiu. Effect of Annealing on Structure and Optical Properties of Y2O3 Thin Films[J]. Journal of Materials Engineering, 2010, 0(2): 47-51.
Thin films of Y2O3 were successfully deposited onto Si(100) substrate by pulse electrostatic spray assisted vapor deposition method.The morphology,structure and optical properties of Y2O3 films were studied.The results of XRD analysis indicated that Y2O3 thin films were cubic with(111) oriented growth after annealing,whilst the Y2O3 thin films were amorphous before annealing.The results of FE-SEM analysis showed that Y2O3 thin films after annealing were dense and smooth.The refractive index of thin films was raised and extinction coefficient of the Y2O3 films was decreased after annealing.
WANG Hongxing, LI Yingguang. Effect of Al Content on Microstructure and Mechanical Properties of Siliconized Coating on Surface of Electro-deposited Nickel Layer on Copper[J]. Journal of Materials Engineering, 2010, 0(2): 52-57.
A layer of electroplating nickel was deposited on copper specimens.Subsequently,these electroplated specimens were siliconized at 900℃ for a period of 12h by slurry pack cementation process.A slurry pack cementation mixture was composed of SiO2 used as siliconizing source,pure Al powder as reducer,a dual activator of NaF+NH4Cl and albumen(egg white) as cohesive agent.The effect of Al content on the microstructure and the mechanical prosperities of the siliconized coating have been studied.The results showed that the microstructure of the coating is mainly depended upon the Al content.As the Al content in mixture powder increased,the phases of the coating were transformed from Ni3Si+Ni31Si12 to Ni31Si12+Ni2Si,and to Ni3Si+NiAl,correspondingly,and the process of slurry pack cementation were also changed from the siliconizing-base dual process to the aluminizing-base dual process;the microhardness increased and the friction coefficient of siliconized coating decreased from 0.37 to 0.18 with increasing the content of Al powder from 10%(mass fraction,the same below)to 45%,1/2,1/5 of those of pure copper,respectively.
LIU Huicong, XING Yang, LI Weiping, ZHU Liqun. Corrosion on Surface Coating of Electronic Devices in Hygrothermal Environment[J]. Journal of Materials Engineering, 2010, 0(2): 58-63.
In view of the corrosion problem of electronic devices in storage environment,electronic devices with Ni/Pd/Au coatings were investigated through humid temperature test.Simultaneously,the influence of temperature,relative humidity,and surface conditions including salts,additional lead scratches and dust on the corrosion of surface coating was evaluated.Scanning electron microscopy(SEM) and Energy dispersive spectroscopy(EDS) were used to study the corrosion behaviors of the electronic devices in hygrothermal environment.The results showed that there were three corrosion susceptible locations on the surface of component leads,namely exposed base metal from trimming,cracks due to forming,and porosity on the coating surface.Temperature and relative humidity(RH) greatly affected the corrosion of electronic device.Corrosion rate was accelerated when the temperature was higher than 40℃ and the relative humidity was higher than 80%.Salt and dust on the surface also have obviously accelerated impacts on the corrosion.Component surface with salt and dust could be eroded even at 30% relative humidity.
QIAO Yanqiang, GUO Xiping, REN Jiasong. Oxidation Behaviors of Si-Cr Co-deposition Coatings on a Ti-Nb-Si Based Ultrahigh Temperature Alloy at 1250℃[J]. Journal of Materials Engineering, 2010, 0(2): 64-68,73.
Si-Cr co-deposition coatings were prepared on a Ti-Nb-Si based ultrahigh temperature alloy by pack cementation processes at 1350℃ for 10h.The oxidation behaviors of the coating specimens were examined isothermally at 1250℃ for 5,10,20,50h and 100h in static air.X-ray diffraction analysis(XRD) and scanning electron microscopy with energy dispersive spectroscopy(SEM/EDS) were used to identify the microstructure,compositional distribution and phase constituents of both coating and the scale developed during oxidation.The results revealed that the Si-Cr co-deposition coating was composed of 4 layers.The outermost layer was mainly composed of(Nb1.95Cr1.05)Cr2Si3 and(Ti,X)5Si3 phases(X represents Nb,Cr and Hf elements).Both the sublayer and transitional layer consisted of(Ti,X)5Si3,and(Ti,X)5Si4 was found as the main phase constituent in the intermediate layer.The oxidation of the coating specimens at 1250℃ resulted in the formation of scales with an outer layer composed of Nb,Cr doped TiO2 and an under layer composed of SiO2.The oxidation kinetics of the bare alloy at 1250℃ followed a linear law.However,the oxidation kinetics of the coating specimens could be described in terms of piecewise parabolic laws.The parabolic equation was y=15.81+3.92t1/2 within 20h,and it was y=-82.71+27.12t1/2 from 20h to 100h.The parabolic rate constant within 20h was lower than that from 20h to 100h by 1 order of magnitude.The outer layer with a higher Cr content had a better oxidation resistance than both intermediate layer and transitional layer of the coating at 1250℃.
JIANG Haitao, TANG Di, MI Zhenli, CHEN Yulai. Influence of Processing Parameters of Hot Stamping to Mechanical Properties of Martensite Steel and Segregation of Boron[J]. Journal of Materials Engineering, 2010, 0(2): 69-73.
The hot stamping processes of B-bearing steel sheet after hot rolling were simulated at Gleeble 1500,the microstructure and mechanical properties were analyzed at different heat treatment conditions,and the segregation of boron and precipitation of boron phase were investigated by X-ray diffraction analysis and particulate tracking autoradiograph(PTA) technology.It can be found that the boron segregation and austenization of martensite steel were accelerated with the increasing of heating temperature and holding time.The suitable content of boron can provided enough hardenability so that martensitic transformation can be completed thoroughly in the tested steel.The deformation during hot stamping process was able to break austenite and accelerate the phase transformation in order to obtain fine martensite.If cooling rate is not enough high after heating,the boron phase easily precipitates at grain boundary continuously,which leads to the decreasing of hardenability.
GONG Peng, ZHANG Kun, DAI Shenglong, LU Zheng. The Effect of Homogenization Treatment on Microstructure and Forging of a New Aluminum Alloy[J]. Journal of Materials Engineering, 2010, 0(2): 74-77.
The effect of different homogenization on microstructures and the performance of forging were investigated depending on the SEM,TEM,high temperature tensile and impact analytical method about a new semi-continuous casting Al-Zn-Mg-Cu alloy.The results point out that the dendritic structure and non-equilibrium phase gradually dissolved into the matrix along with the homogenization temperature increasing.When the temperature below 450℃,the dendritic structure remained in the matrix which decreased the hot-working plasticity.When the homogenization temperature increased to 470℃,the new alloy had the best hot-working plasticity depending on the dendritic structure dissolved into the matrix.Relying on the test of hot-working plasticity,it can conform the suitable forging temperature is between 380-430℃ for the new alloy homogenized 470℃.Therefore,the propitious homogenization treatment of the new alloy is 470℃/36h and the proper forging temperature is 380-430℃.
YU Zhishui, LI Ruifeng, QI Kai. Interfacial Structure and Analysis of Aluminum Alloy MMCs Brazed Joint with Application of Electromagnetic Field[J]. Journal of Materials Engineering, 2010, 0(2): 78-80,90.
In order to control the pushing/engulfment behavior of the reinforced particles,the brazing technology and joint interfacial microstructure of aluminum alloy MMCs SiC/A356 using Zn-Al filler is studied in an electromagnetic field at different AC square peak value.Results show that the behavior of the reinforced particles in solidified metal is controlled effectively by applying electromagnetic force when the magnetic intensity is 0.5T,AC square current frequency is 100Hz and peak value is 70A.The SiC particles distribute uniformly and dispersive throughout the brazing seam without segregation phenomenon at the interface.
ZHOU Liang, DENG Yunlai, JIN Kun, ZHANG Xinming. Effect of Pre-treatment on Microstructures and Mechanical Properties of 2124 Al Alloy Creep Aging Sheet[J]. Journal of Materials Engineering, 2010, 0(2): 81-85,96.
Effect of pre-treatment(15% deformation+100℃×5h aging) before creep aging process on microstructures and mechanical properties of 2124 Al alloy creep aging sheet was investigated.The results show that coarse rich-Fe(Si) particles have broken because of effect of stress concentration during creep aging process,which is helpful to improve performance of the sheet.Stress oriented effect of θ′phase precipitating on {100} plane is observed in the sheet treated by creep aging process without pre-treatment.But presence of the dispersed T phase particles near restrains the stress oriented effect by causing severe crystal lattice distortion,and promoting nucleation and growth of θ′phase.It is found that pre-treatment causes Ω phase precipitating on {111} plane,increasing strength significantly without deceasing elongation in 2124 Al alloy creep aging sheet.
YANG Wei, ZHAO Yufeng, YANG Shiyan. Effects of Characteristic and Parameters of Power Supply on Micro-arc Oxidation Coatings Property and Energy Consumption[J]. Journal of Materials Engineering, 2010, 0(2): 86-90.
Power supply is one of the key equipments of micro-arc oxidation(MAO) treatment,and it has important influence on MAO.This paper reviewed the effects of characteristic and parameters of power supply,such as controlling modes,current density,voltage,frequency and so on,on the property of MAO coatings,such as phase composition,surface morphology,and corrosion resistance and so on.In addition,the influences of power supply on the energy consumption of MAO treatment were summarized.It was revealed that the effects of characteristic and parameters of power supply are essentially the effects of discharging energy of a single pulse.The power supply which could accurately regulate pulse energy will be the research emphasis.
CHEN Yongxiong, LIANG Xiubing, LIU Yan, XU Binshi. Development of Electric Arc Spray Forming Technology[J]. Journal of Materials Engineering, 2010, 0(2): 91-96.
As a key metal Rapid Prototyping(RP) technology,electric arc spray forming was concerned in the present study and compared with the near-net-shape spray forming and plasma spray forming processes.The development status of the electric arc spray forming process applied in the field of rapid tooling was reviewed,and the key factors influencing the spray forming process were discussed in detail,such as spraying material,atomization and deposition of the droplets,heat and mass transfer,residual stress and oxidation.Finally,some suggestions about the developing directions and solving methods for arc spray forming thick tools were put forward.
