SONG Pei-wei, LI Hong-yan, WANG Yong-shan. Microstructure and Mechanical Properties of As-cast Mg-4Al-2Si Magnesium Alloy[J]. Journal of Materials Engineering, 2010, 0(1): 1-4.
Mg-4Al-2Si(AS42)magnesium alloys were prepared by the gravity casting.Microstructure and mechanical properties at room temperature of the as-cast AS42 alloy were investigated.The results show that the as-cast microstructure consists of α-Mg matrix,β-Mg17Al12 phase and Mg2Si phase.The network and rod shaped β-Mg17Al12 phase distribute on grain boundary,and the coarse Chinese script type Mg2Si particles distribute on grain boundary or transcrystallization,while the block-like Mg2Si distributes in matrix(α-Mg).The hardness of the alloy is 64.5HV,ultimate tensile strength,yield strength and elongation are about 113.5,86MPa and 4.1% respectively.The fracture forms of the alloy is quasi-cleavage brittle fracture.
SHI Chun-ling, LI Hai-qin. Application Research of Using Polymer Glycols Quenching Medium in Heat Treatment of Al Alloy[J]. Journal of Materials Engineering, 2010, 0(1): 5-8.
The research of using the polymer glycols quenching medium in heat treatment of Al alloy was discussed.The water-polymer glycols quenching solution of concentration 16% and 33% were prepared.A series of comparative tests were carried out by using typical aluminum alloys and parts.The results show that the tensile performance,conductivity and corrosion resistance after heat treatment using polymer glycols quenching medium are in the same lever compared with quenching using water.Deformation of parts obviously decreased after quenching by using polymer glycols quenching medium.
LIU Qiang, PEI Gao-lin, MI Zhi-an, SU Zheng-tao. Adhesive Property and Damping Property Between Oversea and Domestic Constrained-layer Damping Tapes[J]. Journal of Materials Engineering, 2010, 0(1): 9-11,18.
The constrained-layer damping tapes including the oversea and the domestic were tested and compared.The differences between the oversea and the domestic in peel strength and damping properties were discovered.The results show that the domestic constrained-layer damping tapes possess higher peel strength than that of the oversea.And the peel fracture of the domestic constrained-layer damping tape was hybrid fracture.The oversea constrained-layer damping tapes possess larger maximum loss factor and wider damping temperature range than that of the domestic tape.The loss factor of two kinds of damping tapes increases and the temperature at the maximum loss factor reduces with increasing the layers of constrained-layer damping tapes.
QI Tao, GUO Xi-ping. Effect of Y2O3 on Microstructure of Silicide Coatings on Nb-silicide-based Ultrahigh Temperature Alloy[J]. Journal of Materials Engineering, 2010, 0(1): 12-18.
Si-Y2O3 co-deposition coatings on an Nb-silicide-based ultrahigh temperature alloy were prepared by pack cementation process at 1050℃ for 10h.The structure,phase constituents and compositional distribution of coatings were investigated by SEM,EDS and XRD and compared with those of the coating prepared by depositing Si under the same conditions.The results show that no evident new phases form on the surface layer of Si-Y2O3 co-deposition coating.Coatings prepared with different content of Y2O3(in the range of 0.5%-5%,mass fraction)in the pack mixtures have the similar structure,which is composed of a(Nb,X)Si2(X represents Ti,Hf and Cr elements)layer,a(Nb,X)5Si3 transitional layer and an Al-rich diffusion zone.The Si-Y2O3 co-deposition coatings are more compact than the simple Si deposition coating.EDS analyses reveal that the distribution of Y in the coating are not uniform.The Y content appears the highest in the place near the interface between substrate and transitional layer and it gradually decreases from the substrate to the coating surface.Furthermore,the Y concentration in the coating firstly increases and then decreases with the increase of the content of Y2O3 in pack mixtures.The coating growth can be catalyzed obviously when the content of Y2O3 in the pack mixtures ranged from 1% to 2%(mass fraction).
CHENG Zhi-peng, XU Ji-ming, ZHU Yu-lan, LI Dong, YANG Yi, LI Feng-sheng. Synthesis of Ni-B/Al Nanocomposites by Electroless Plating[J]. Journal of Materials Engineering, 2010, 0(1): 19-22.
Ni-B/Al nanocomposites were prepared via electroless plating by using KBH4 as a reducing agent.The bath components and processing parameters were investigated in order to obtain the optimized condition.The surface morphology,crystal phase,chemical composition and specific surface area of the as-prepared nanocomposites were characterized by SEM,XRD,inductively coupled plasma(ICP)atomic emission spectrometry and Brumauer-Emmett-Teller(BET)specific surface area.The results show that a continuous layer of 80-100 nm amorphous Ni72B28 is covered on the surfaces of Al particles,and BET data of the as-prepared nanocomposites are up to 26.21m2·g-1.
HUANG Wei-jiu, XUE Yan. Effect of Surfactants on Electroless Plating Ni-P-SiC Composite Coating on Magnesium Alloy[J]. Journal of Materials Engineering, 2010, 0(1): 23-27.
The effect of different surfactants,such as neopelex(ABS-Na),lauryl sodium sulfate(DS),polyethylene glycol(6000)(PEG(6000)),Tween-80 and their mixtures,on the stability of plating solution,deposition velocity of electroless plating Ni-P-SiC,morphology and performances of Ni-P-SiC composite coating on magnesium alloys was studied.Further,the optimization surfactant for electroless plating Ni-P-SiC composite coating on magnesium alloys was selected.The results show that the surfactants can evidently improve the stability of electroless plating Ni-P-SiC solution,the species of surfactants have an important effect on deposition velocity,the deposition velocity of the plating solution containing neopelex+polyethylene glycol(6000)is the fastest.Based on the surface quality,hardness and anti-corrosion performance of the Ni-P-SiC composite coating,mixture of lauryl sodium sulfate+polyethylene glycol(6000)is selected as the best adaptive surfactant for electroless plating Ni-P-SiC composite coating on magnesium alloys.
GUO Feng, LI Ping, SU Xun-jia, HOU Gen-liang, GU Jian-rong. Microstructure and Properties of Strengthened Coating on LY12 Alloy Surface Fabricated by Electrospark Deposition[J]. Journal of Materials Engineering, 2010, 0(1): 28-31.
The LY12 alloy surface was strengthened by electrospark system in air medium,with Ti6Al4V titanium alloy as electrode.The microstructure,element distribution and phase construction of strengthened coating were analyzed by scanning electron microscopic,energy-dispersive spectrum and X-ray diffractometer respectively.Furthermore,the microhardness distribution and wear resistance of strengthened coating contrast to LY12 substrate were studied by microhardness tester and abrasion tester respectively.The results show that excellent metallurgical bonding between the coating and the substrate is obtained.The coating is mainly composed of Ti-Al intermetallic compounds and Ti/Al oxides and nitrides,the microhardness can reach HV596.Compared with the LY12 alloy substrate,the wearing volume loss of strengthened samples is just one seventh.The surface performance of LY12 alloys is dramatically improved.
HUANG Li-guo, FU Da-jun, GAO Zhi-yu. Effects of Electromagnetic Field on Primary Si Phase of Hypereutectic Al-18%Si Alloy[J]. Journal of Materials Engineering, 2010, 0(1): 32-35,41.
The article is aimed to study the effects of alternating current(AC)electric field,the direct current magnetic field and the composition of both on the primary Si phase of the hypereutectic.The results show that AC field,the direct current magnetic field and electromagnetic vibration can all lead to the refining process of the size of the hypereutectic Al-Si alloy.AC electric field changes both the size and amount of silicon atom clusters,increases the nucleation rate,and refines the primary Si phase.The direct current magnetic field restrains the nucleation and growth of the primary Si phase through the effect of electromagnetic braking.The refinement of the electromagnetic vibration increases the degree of supercooling through weakening the constitutional supercooling of the alloy and the temperature gradient.Comparatively,the primary Si phase tends to be smaller under the effect of electromagnetic vibration.
GAO Jia-cheng, FAN Ke, LI Rui, QIU Ri-sheng. Preparation Process of Mg-12Mn Master Alloy[J]. Journal of Materials Engineering, 2010, 0(1): 36-41.
The Mg-12Mn master alloy was successfully prepared by electromagnetic stirring method in the present work.The key processing parameters such as the particle size of Mn powder,the power of electromagnetic stirring,the stirring time and the way of cooling were developed for the higher Mn-content and the better distribution of Mn by orthogonal experiment.In addition,Mg-12Mn master alloy was successfully applied to manufacture MB1 by burden calculation.The master alloy was characterized by chemical analysis,OM,XRD.The results show that in the experiment conditions,the Mg-12Mn master alloy with excellent performance can be manufactured by adding Mn powder with the particle size ranged between 150-68μm in stirring at 10kW for 4min,cooling in the mold made of Cu.Mn yielding rate of MB1 is 86.1%.
GONG Hai, WU Yun-xin, LIAO Kai. Analysis on Validity of Residual Stress Measurement Methods for Aluminum Alloy Thick-plate[J]. Journal of Materials Engineering, 2010, 0(1): 42-46.
The validity of both crack compliance method and layer removal method measurement results was evaluated by analyzing the stress distribution uniformity of the test coupons.The results show that the two methods can describe the real stress distribution effectively for test coupon with mean stress distribution;while for test coupon with unmean stress distribution,the measurement results are synthetic stresses,and can not describe a real stress distribution.In order to describe the real residual stress distribution of test coupon accurately,it is necessary to combine the use of FEM,surface stress measurement and deep floor stress measurement,and to give an integrate evaluation.
LIU Gang, ZHANG Dai-jun, ZHANG Hui, AN Xue-feng, YI Xiao-su, ZHANG Zhong. Mechanical Properties of Nanoparticles Modified Epoxy Matrix and Composites[J]. Journal of Materials Engineering, 2010, 0(1): 47-53.
The epoxy matrix toughened by nano-Al2O3 was prepared by mechanical mixing method.The mechanical properties of epoxy matrix with different nano-Al2O3 content were researched.The fracture toughness of the epoxy matrix was studied by compact tension test method.The glass-fiber reinforced composites were fabricated using the toughened epoxy matrix and the mechanical properties of the composites were investigated.The results indicate that the improved fracture toughness of epoxy matrix and the enhanced bonding between fibers and resin matrix can be attributed to the nanoparticles.Therefore,the interlaminar shear strength of the composites is improved obviously,while the other mechanical properties increase faintly.
MU Yun-fei, LIN Li, GUO Guang-ping, LI Xi-meng. CFRP Random Pores Model and Numerical Simulation of Porosity Ultrasonic Testing[J]. Journal of Materials Engineering, 2010, 0(1): 54-57,61.
Based on carbon fiber reinforced plastics(CFRP)random pores model,finite difference time domain(FDTD)was proposed to simulate the inspection of CFRP porosity using ultrasonic attenuation method.Numerical simulation and experiment test were carried out.The specimen was multilayer,hot pressed prepreg,epoxy resin based,and one direction carbon fiber reinforced plastic.Its thickness was 2mm,and fiber mass fraction was 69%±3%.The porosities range from 0.065% to 4.96%.A similar law on the relation between CFRP porosity and ultrasonic attenuation coefficient was found from simulation and experiment.The result shows that CFRP porosity inspection can be simulated using the random pores model and FDTD method.
QIAN Tian-cai, MOU Lei, ZHOU Lie-xing. Microstructural and Photocatalysis Properties of TiO2 Thin Films with Ce-doping and La-doping[J]. Journal of Materials Engineering, 2010, 0(1): 58-61.
TiO2 thin films with Ce-doping and La-doping were prepared by sol-gel method through the mixed reaction of tetrabutyt titanate with ceric sulfate crystal(and lanthanum sesquioxide).The photocatalytic experiment to the formaldehyde and the XRD structural analysis with Rietveld(whole-pattern fitting)method show that crystal and microstructure of thin films change with doping quantity and heat treatment temperature,thus catalytic performance of TiO2 is improved substantially at optimum conditions.
LI Qing-hua, HU Shu-bing, LI Xing-zhi, XIAO Jian-zhong, WANG Ya-jun, LIU Xin, JI Long-bo. Microstructure Heterogenicity and Fatigue Property of Weld Joints of TC4 Titanium Alloy[J]. Journal of Materials Engineering, 2010, 0(1): 62-68.
Local gradient simulation technology was used as a new method to describe the microstructure heterogenicity of TC4 weld joints,by observing the microstructure,testing the dimension of columnar grains,the lateral microhardness and conducting the fatigue experiment.The results show that the heterogenicity of the microstructure has an influence on the fatigue property of the weld joints.Fatigue life of the bell shaped weld joint with relatively homogeneous microstructure is higher than the wedge shaped weld joint with heterogeneous microstructure.The initiation of fatigue cracks is in the HAZ and the fusion line,where have high gradient of the lateral microhardness.
HE Gang. Impurities Composition and Grain Structure Changes of Copper-based Methanol Catalyst Before and After Inactivation[J]. Journal of Materials Engineering, 2010, 0(1): 69-73.
Electron spectroscopy,X-ray diffraction,SEM,physical and chemical equipment such as adsorption apparatus and chemical analysis were used for the methanol industrial catalyst research of the composition and structure before and after inactivation.The results show that sulfur impurities influence on methanol content of the catalyst components can reach several hundred times the initial concentration.The major impact of sulfur on the components concentrated in the upper region near the surface,and the highest concentration appears in the 1R/6 position.The chemical forms of sulfur mainly β-ZnS(cubic)form of existence.Chlorine impurity effects on the methanol catalyst components can reach 10 times the initial concentration and has enormous harm.Strong penetration of chlorine can destroy the entire structure of the catalyst,and often accompanied by the coexistence of sulfur chloride.Chlorine can make Cu and ZnO grains rapidly increase,the chemical forms of chlorine mainly ZnCl2 and CuCl2 form of existence.Catalyst structure in the course of use will change,grain size grew up,specific surface area decreased,resulting in decreased activity and loss.
DENG Jiang-hui, ZHAO Bei-jun, ZHU Shi-fu, HE Zhi-yu, GUO Nan, LI Jia-wei. Observation of Etching Morphology of CdGeAs2 Crystal[J]. Journal of Materials Engineering, 2010, 0(1): 74-76.
The etch pits morphology of germanium cadmium arsenide(CdGeAs2)crystal grown using vertical Bridgman method was observed by metallographic microscope and scanning electron microscope(SEM).By mechanical grinding,physical polishing,with the non-preferential etchant 3%(mass fraction)bromine methanol(BM)solution to polish the CdGeAs2 crystal wafer about 1min,a smooth surface without scratching was obtained.A preferential etchant HCl:HNO3:H2O=1:1:1(volume ratio)for CGA crystal was studied.It can be used to produce well-defined etch pits morphology of(101)face at room temperature after chemical polishing.The triangular shape of etch pits with clear and consistent orientation was observed in the optical microscope and scanning electron microscope,and the reasons for formation of triangular shape of etch pits on(101)face were also analyzed in theory.
WANG Fei-jun, SHAO Zi-qiang, WANG Wen-jun, LU Shao-yi, LI Yong-hong, FENG Zeng-guo. Effect of Organic Solvent on Structure and Property of Polyanionic Cellulose[J]. Journal of Materials Engineering, 2010, 0(1): 77-81.
The influence of ethanol,isopropanol and mixture thereof used during the polyanionic cellulose(PAC)manufacturing on the structure of alkali cellulose and PAC was studied by means of X-ray diffraction,microscope,1H-NMR and chemical titrimetry method.The result shows that the structure and property of alkali cellulose and PAC is hardly dependent on the organic solvent in the manufacturing process.With increasing of isopropanol,swelling ratio and adsorption quantity of cellulose base increase and crystalline grade of cellulose decrease,degree of substitution of the PAC and its solubility improve,and the distribution of the substituent in C2,C3,C6 of the anhydroglucose unit(AGU)becomes more even.
NI Jia-ming, LI Zhu-guo, HUANG Jian, WU Yi-xiong. Resistance Property to Intergranular Corrosion of HastelloyC-4 Welding Joint[J]. Journal of Materials Engineering, 2010, 0(1): 82-84,88.
HastelloyC-4 pipeline was welded by multi-pass arc welding.Contrastive determination of resistance to intergranular corrosion of HastelloyC-4 and its joint was conducted.Microstructure and composition of welding joint were analyzed by using microhardness,optical metallography,scanning electron microscopy(SEM)and energy dispersive spectrum analysis(EDS).The results show that the average of intergranular corrosion velocity of joint samples is smaller than that of base alloy samples.With filler wire including higher Cr component,Cr component of weld metal grain boundary is higher than that of base alloy.And with appropriate energy input,follow pass welding offers solution treatment to former weld metal.Both of them improve resistance property to intergranular corrosion of HastelloyC-4 arc welding joint in oxidizing media.
LI Hong-en, SHA Ai-xue. Effects of Hot Process Parameters on Flow Stress and Microstructures of TC18 Titanium Alloy[J]. Journal of Materials Engineering, 2010, 0(1): 85-88.
The effect of strain rate and deformation temperature on the deformation resistance and the microstructure of TC18 titanium alloy was studied through heat simulating test at 700-950℃ and strain rate 0.001-50s-1.The results show that,when the deformation temperature increases or the strain rate decreases,the real stress can be reduced obviously.Comparing to deformation in β phase,deformation resistance in α+β phase is more sensitive to the change of temperatures.When α+β phase deformed,α and β phases join in deformation at the same time,but deformation degree is different.Preliminary equiaxed alpha phase is elongated slightly and beta phase changes to fiber texture along deformation direction.When β phase deformed,beta phase is fibrous along metal flowing direction,and equiaxed beta grain can be seen when the deformed temperature is above 950℃.
HU Yao-bo, DENG Juan, WANG Jing-feng, PAN Fu-sheng, CHEN Yu-an. Research Status of Magnesium Matrix Composites with High Damping Capacity[J]. Journal of Materials Engineering, 2010, 0(1): 89-93,98.
The research status of damping capacity of magnesium matrix composites was briefly introduced.The micromechanism of high damping magnesium matrix materials was related with dislocation movement and interfaces slip damping mechanism,and the influence of matrix components,styles and contents of reinforcements,interface between matrix and reinforcement,strain amplitude,temperature,frequency,treatment processes on damping capacity of magnesium matrix composites was respectively discussed.Finally,how to design and develop high damping magnesium matrix composites was analyzed.
BU Heng-yong, LU Chen. Research and Development of Cold Spray Technology[J]. Journal of Materials Engineering, 2010, 0(1): 94-98.
This paper summarized the processing principles and characteristics of the cold gas dynamic spray(cold spray)technology.It emphasized to discuss the coating deposition mechanism and the parameters which influenced the critical velocity of the particles and the coating quality.It is believed that using the proper parameters in the coating process is vital for getting high quality coating,improving the structure of the spray gun,fabricating functional and composite coatings are considered as the main directions of the cold spray in future.
