最新刊期
卷 30 ， 期 8 ， 2010
- 摘要：CuCr alloy was prepared with CuO,Cr2O3 and Al as reactants by SHS,and effects of different additives on the microstructure and purity of alloy prepared were investigated. The results reveal that the alloy is composed of Cu phase,Cr phase and a little Cr23C6 phase,and slag consists of Al2O3 and Na3AlF6 as well as a little Cr phase. Cr existence shows the dis-ideal separation effects of metal from slag. With increasing in Na3AlF6 addition,microstructure of the alloy exhibits uniform and compact as a result of effectively removing oxides inclusion in the CuCr alloy,meanwhile,oxygen content in the alloy is decreased with increasing in residual Al content,and purity of the alloy is more than 97%.关键词：SHS;CuCr Alloy;Slag;SEM
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发布时间：2023-12-18 - 摘要：Mechanical properties and deformation behavior of sprayed-deposited SiCp/7090Al composites rolling sheet were investigated by uniaxial tensile testing on WDW-E200 tensile tester at ambient temperature and 300450 ℃ with stain rate of 0.1s-1. Meanwhile,microstructure,mechanical properties and fractographies of the composites at different tensile temperatures were also observed. The results show that tensile flow stress in the composites sheet is decreased with increasing in deformation temperature. In addition,interface of Al/SiC is weakened and particle breakage is reduced with tensile temperature increase,while the elongation of the composites is increased from 3.0% to 85.07%.关键词：Spray Deposition;High Strength Aluminum Alloy;Composites;Flow Stress;Fracture Behavior
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发布时间：2023-12-18 -
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- 摘要：During the actual casting process,the heat resistance exists at the interface of casting/mold because of air gap or coatings. Boundary conditions at the interface are changed with temperatures to result in complex heat transfer,which influences the solidification and cooling rate remarkably. Interfacial heat transfer coefficient （IHTC）is a key parameter used to characterize the heat resistance between the castings and the mold. During the numerical simulation of solidification,the IHTC is an important boundary condition. A new method was presented to determine the equivalent IHTC at the castings/mold interface during solidification based on deducting the solvent. A simple shaped part was used as benchmark. Different constants of IHTC were used to simulate the temperature curves,which were compared with the actual temperature curves,when the former is nearly to the later,then the coefficient was regarded as the equivalent IHTC at the castings/mold interface. The blade with different thickness was used to conduct verification experiment. The results reveal that the method is simple,convenient and feasible,exhibiting a wide engineering application prospect.关键词：Equivalent IHTC;Inverse Method;Solidification Simulation
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发布时间：2023-12-18 - 摘要：Background around bubbles exhibits very complex due to the characteristics of very easy oxidation and ignition of the alloy melt. The wavelet analysis in differential scale was employed to keep track of time and frequency information of character signal. With the scale zooming out,true signal was enhanced and noise was weakened. Existence of the first bubble was effectively detected based on wavelet analysis in differential scale combining with open operation of mathematic morphology according to difference of target,disturbed background and noise. The results verify that the method is feasible and effective.关键词：Magnesium Melt;First Bubble;Wavelet Analysis;Mathematic Morphology
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发布时间：2023-12-18 - 摘要：Effects of Ca and Si compound alloying on as-cast microstructure of AZ31 magnesium alloy were analyzed by optical microscope （OM）,SEM （scanning electron microscope）,XRD （X-ray diffraction） and EDS （energy dispersive spectrometer）. It is found that Ca element exists in the AZ31 magnesium in form of solid solution phase,and Si element is irrelative with the distribution of Ca in the alloy. Mg2Si phase is created by Si reacting with Mg,meanwhile,Mg17Al12 phase distributed along boundary is gradually converted into particle and acicular phase dispersedly distributes around boundary or in the grain. With increasing in Si addition,partial particles become coarse,and Chinese script Mg2Si phase appears in the matrix alloy. The desirable as-cast microstructure of the alloy can be observed with 0.3% Ca and 0.4% Si compound addition.
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发布时间：2023-12-18 - 摘要：ZA20 coatings were prepared on the surface of AK63 magnesium alloys by cold spraying method. Microstructure of interface between cold sprayed coatings and magnesium alloy matrix was observed by OM （optical microscope）,EMP and EDX. Hardness,bonding strength and wear resistance,corrosion behavior of the samples before and after cold sprayed treatment were investigated. The results reveal that absence of diffusion between matrix alloy and coating and of defects in interface,such as crack,pore and separation,can be observed,showing desirable interface bonding. The hardness of the coating is approximately higher 3 times than that of the alloy substrate. In addition,wear resistance of the magnesium alloy after cold sprayed ZA20 coating is greatly superior to that of magnesium alloy matrix in condition of dry friction or oil lubrication. Self-erosion potential of cold sprayed samples （-0.26V） is far higher than that of magnesium alloy matrix（-1.62V）,leading to in the significant improvement of corrosion resistance.关键词：Cold Spraying;Magnesium Alloy;Zn-Al Coating;Wear Resistance;Corrosion Resistance
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发布时间：2023-12-18 -
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- 摘要：Influence of inlet velocity and pouring temperature of the metal melt on flow field in the copper stave in metal-sand molds was simulated using a finite element software ANSYS. The results reveal that obvious disturbance on the curves of filling velocities can be observed in condition of lower inlet velocities,such as 0.3 m/s and 0.8m/s,while absence of disturbance on the filling velocity curves can be observed with inlet velocity of 1.0 m/s,exhibiting smooth filling process,which can be used for the recommended value of pouring parameters during practical production. Varied-viscosity was adopted in the numerical simulation to predict the effects of pouring temperature on filling velocities. It is found that with increasing in pouring temperature,the filling velocity of metal melt is obviously accelerated,which is beneficial for obtaining larger velocity gradient.
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发布时间：2023-12-18 - 摘要：Die casting machine was selected by analyzing component structure,and 3D design of die casting die was conducted by Pro/E software. And then,through finite element analysis module MACHANIC from Pro/E,the distortion induced by the die locking force and the thermal loading in using process of the die was visualized. Distortion characteristics of the 3D die was observed,which provided a reference to further optimize die design.关键词：Die Casting;Pro/E;Die Distortion
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发布时间：2023-12-18 - 摘要：Semi-solid Al-6Si-2Mg alloy billets with fine spherical grains were prepared by self-developed vibrating wave-like sloping plate device,and effects of different reheating processes on microstructure of the billets were observed. The results reveal that solute diffusion is accelerated,and liquid region near grain boundary tends to be continuous and liquid fraction rises with increasing in holding temperature at a given holding time. Due to the role of interface free energy,average grain size exhibits firstly increase and then decrease,meanwhile,average grain roundness and density show gradually decrease. At a given holding temperature,with extending in holding time,eutectic liquid phase is increasingly raised to be formed a continuous liquid network to separate the grain. To decrease interface free energy,grain size exhibits firstly increase and then decrease,while grain roundness is decreased with raising in liquid fraction. Desirable semi-solid slurry with spherical grain suspending on liquid phase can be obtained with holing at 610 ℃ for 60 min.关键词：Semi-solid;Reheating;Al-6Si-2Mg Alloy;Microstructure
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发布时间：2023-12-18 - 摘要：Thermal simulation compressive experiment was conducted for semi-solid 6063 aluminum alloy billets which was prepared by near-liquidus semi-continuous casting. Based on stress-strain curves at varied temperatures and strain rates,inverse-squeezing process of the semi-solid 6063 aluminum alloy was simulated by the Deform-3D software at 615625 ℃ with strain rate of 0.15s-1 and 60% deformation rate to understand effects of deformation rate,deformation temperature,punch velocity and frictional coefficient and to optimize the processing parameters. The results reveal that with increasing in deformation rates,flow velocity and flow orientation of the alloy in severe deformation zone are distinctly changed,meanwhile,light deformation zone is gradually evolved,which results in the remarkable non-uniformity of deformation. With raising in punch velocity,flow velocity of the billets is accelerated,which is harmful for the formation as a result of aggravating non-uniformity of the whole deformation process. With deformation temperature increase,equivalent strain of the billets in severe deformation zone is obviously increased,while equivalent stress in the billets is decreased. Effects of frictional states on the deformation of billets can be neglected.关键词：6063 Aluminum Alloy;Semi-solid;Inverse-squeezing Process;Numerical Simulation
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发布时间：2023-12-18 - 摘要：Semi-solid alloy melt with different primary structure was prepared by inclined cooling-shearing rheocasting,and spiral samples were made by semi-solid squeezing casting. Characteristic parameters,such as solid phase fraction,grain size and shape factor,of primary phase structure and spiral sample at different filling length were investigated by quantitative metallographic technique to understand effects of filling pressure and filling velocity on primary structure of the semi-solid alloy melt during filling process. The result show that when spiral samples are made by semi-solid squeezing casting with filling pressure of 20120MPa and filling velocities of 0.21.2 m/s,the solid phase fraction,grain size and shape factor along the filling length exhibits wave-like change with little amplitude ,and the position of peak and trough has no definitely relation with the filling length.关键词：Microstructure Evolution;Forming Process Parameters;Semi-solid;Filling Process;Flow along the Filling Process
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发布时间：2023-12-18 - 摘要：Main technological requirements on semi-solid injecting forming for magnesium alloy were described. Based on experiments,control ways of injecting velocity in semi-solid injecting forming were investigated to realize the improvement of some performance in magnesium alloy semi-solid injecting forming machine such as fast dynamic response,stable pressure control and excellent velocity control.关键词：Magnesium Alloy;Semi-solid;Injecting Forming;Velocity Control;Control Ways
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发布时间：2023-12-18 - 摘要：Based on semi-solid forming technology,a two-step forming process for aluminum foam that is semi-solid foaming （SSF） was put forward to control the cell structure of closed-cell aluminum foam. Effects of basic processing parameters of SSF on foaming process and cell structure as well as its optimization were investigated. The results reveal that SSF can control decomposing time of TiH2,realizing secondary foaming process,and Al-Si aluminum foam with uniform cell structure in which cell porosity is 74.6% with cell diameters of 2.13.2 mm and average roundness of 0.812 can be obtained. The optimized processing parameters are as follows:stirring temperature of 580 ℃,stirring time of 0.5 min and stirring velocities of 1200 r/min,re-forming temperature of furnace of 720 ℃ and heating time of 15 min.
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发布时间：2023-12-18 -
- 摘要：Flow distribution of liquid aluminum alloy and its solidification behavior in ADC12 aluminum alloy cam cover for automobile engine were simulated by MAFMA soft at different gate thickness to predict potential defect positions during filling process. The results reveal that gate thickness greatly affect the filling process and distribution of pressure. There exists large temperature-difference and centralized high pressure as well as high velocity impaction around thin-walled gate,resulting in the formation of hot crack. Pressure distribution,entrapped-gas and gas hole defects in the parts are acceptable in condition of gate with thickness of 2.0mm and filling at 50 m/s.关键词：ADC12 Aluminum Alloy;Die Casting;MAGMA Soft
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发布时间：2023-12-18 - 摘要：Fracture samples were prepared from different positions in practical fatigue failure ADC1 castings,and surface morphology and characteristics of the fracture samples were analyzed by SEM （scanning electron microscope） and EDS （energy dispersive spectrometry） to understand origination of fatigue failure of the castings. The results show that there exists pore with a larger size near surface and congregation of large area oxide film in the casting,which are responsible for the fatigue failure of the castings. In addition,the role of pore and oxide film in the process of failure was described.关键词：Practical ADC1 Castings;Fatigue Failure;Pore;Oxide Film
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发布时间：2023-12-18 - 摘要：ADC12 aluminum alloy connecting rod’s cap was manufactured by squeezing casting. Effects of pouring temperature and specific pressure on mechanical properties of connecting rod’s cap formed were investigated. The results reveal that ADC12 alloy connecting rod’s cap with a higher surface quality and mechanical properties can be successfully manufactured by squeezing casting. Pouring temperature and specific pressure are closely related to the mechanical properties of the connecting rod’s cap formed. Tensile strength and elongation of the connecting rod’s cap formed by squeezing casting with 250MPa at 700 ℃ can make 366 MPa and 6.5%,respectively.关键词：Squeezing Casting;ADC12 Aluminum Alloy;Connecting Rod’s Cap;Mechanical Properties
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发布时间：2023-12-18 - 摘要：Service life of H13 and 3Cr2W8V hot working tool steel in die casting pure copper was analyzed. H13 steel mould and 3Cr2W8V steel mould are failure in die casting pure copper as a result of high temperature resulting in the occurrence of thermal fatigue crack with large size,so their service life in the die casting pure alloy is far lower than those in die casting aluminum alloy. Although service life of H13 steel is superior to that of 3Cr2W8V steel,it only reaches up to 160 cycles.
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发布时间：2023-12-18 - 摘要：Operation process of coating slurry-sand ceramic mold investment casting and its application in copper art castings were introduced,meanwhile,characteristics of the ways and points for attention in operation process were analyzed.关键词：Coating Slurry-sand;Ceramic Mold Investment Casting;Copper Art Castings
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发布时间：2023-12-18 -
- 摘要：There often exists gas hole and leakage defects in lost foam casting aluminum alloy straight six-cylinder engine housing. Origination of the defects is very complex. Filling and solidification process of the engine housing were simulated to predict potential defect position. The results reveal that existing gating system can result in severe temperature gradient in the engine housing after filling. Meanwhile,different ingates exhibit distinctly different in fluid volume,where the maximum different value reaches up to 20%,which is responsible for the formation of gas hole in engine housing as a result of not realizing self-feeding.关键词：Straight Six-cylinder Engine;Lost Foam Casting;Numerical Simulation;Gas Hole
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发布时间：2023-12-18 - 摘要：The production of lost foam casting aluminum alloy cylinder cover and cylinder body was described,focusing on pattern assemble,gating system design,coating brushing and pouring as well as process control.关键词：Lost Foam Casting;Aluminum Alloy;Cylinder Body;Cylinder Cover
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发布时间：2023-12-18 - 摘要：Bi-metal composite hammer head was produced by electroslag casting,in which high Cr cast iron was used for hammer head production and carbon structural steel was adopted in hammer handle. Microstructure and properties of the composite hammer head were analyzed. The results show that there exists a deeper metallurgical bonding zone between the hammer head and hammer handle,showing occurrence of the diffusion in two materials and realizing the desirable bonding. The experimental results verify that the service life of bi-metal composite hammer head is about 2 times higher than that of high Mn steel ones.关键词：Electroslag Casting;Bi-metal;Composite Layer;Microstructure and Properties
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发布时间：2023-12-18 - 摘要：A new method of fabricating ceramic matrix composites using Ni-induced pressureless infiltration was presented,that is,firstly,Ni/Al2O3 composite ceramic preforms were prepared by powder metallurgical method,then,the Ni/Al2O3 composite ceramic preforms were infiltrated with stainless steel melt at 1600℃ in vacuum,finally,stainless steel infiltrated reinforced aluminum ceramic matrix composites were successfully prepared. Microstructure of steel/ceramic bonding interface was observed by SEM （scanning electron microscope）,and elemental content in around bonding interface of the composites obtained was analyzed by EDS （energy dispersive spectrometer）,and interfacial reactive products were characterized by XRD （X-ray diffraction）,and interface bonding strength was measured by tensile testing. The results reveal that the steel melt can be infiltrated into the ceramic preforms through Ni liquid channels and form new Ni-Fe alloy. Interfacial reaction occurs between stainless steel and the composite ceramic,and the maximum interfacial bonding strength reaches up to about 67.5MPa.关键词：Ni/Al2O3 Composite Ceramic Preforms;Pressureless Infiltration;Stainless Steel/alumina Ceramic Composites;Bonding Interface
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发布时间：2023-12-18 - 摘要：Composition and microstructure of Ti coating prepared by low pressure arc spraying method were investigated,and effects of spraying parameters on impurity content in the coating prepared and morphology of sprayed particle were analyzed. The results reveal that it is still difficult to prevent the coating from oxidation and nitridation in Ar atmosphere,so it is necessary for the preparation of a dense coating in low pressure. In addition,the role of deformation plus recrystallization treatment in the boundary among sprayed particles was described. Meanwhile,corrosion resistance of the coating was examined.关键词：Low Pressure Spraying;Ti;Coating;Sprayed Particle;Microstructure;Corrosion
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发布时间：2023-12-18 - 摘要：Brown ceramic oxide coatings were prepared on AZ91D magnesium alloys by micro-arc oxidation,and effects of different NaVO3 concentration on the color,microstructure and properties of the coatings were investigated. The results reveal that with increasing in NaVO3 concentration,growth rate of the oxidation coatings is increased,and corrosion resistance of the coating exhibits firstly increase and then decrease,meanwhile,the color of the coatings becomes dark brown gradually. However,excessive NaVO3 concentration is harmful for the micro-oxidation process. EPMA analysis shows that the coating is mainly contained Mg,Al,V,O and little P element,and absence of the phase containing P element can be observed in the XRD,which is attributed to little P content in the coating and thin coatings resulting in the little deposition containing P phase.关键词：Magnesium Alloy;Micro-arc Oxidation;Coloring
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发布时间：2023-12-18 - 摘要：Solidification structure of cast AL-25Si-xFe-yMn alloy was observed by SEM （scanning electron microscope）,EDX and XRD,where Mn/Fe in weight ratio is in range of 01. The results show that Mn can greatly refine microstructure of the alloy as a result of creation of α-Al15（Fe,Mn）3Si2 phase substituting for acicular δ-Al4FeSi2 and β-Al3FeSi phase. In addition,with increasing in Fe/Mn weight ratio,α-Al15（Fe,Mn）3Si2 phase is increased and acicular phase is decreased. When Fe/Mn weight ratio is 1,α-Al15（Fe,Mn）3Si2 phase is observed in the alloy only.关键词：High Si Aluminum Alloy;Fe Phase;Mn;Casting
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发布时间：2023-12-18 - 摘要：Effects of high-intensity ultrasonic treatment on microstructure and mechanical properties of hypereutectic Al-20Si alloy were investigated. The results reveal that primary Si phase in the Al-20Si alloy can be converted from coarse plate gradually into fine spherical particle with uniform distribution after high intensity ultrasonic treatment,which is responsible for the improvement of tensile strength and elongation of the alloy. Observation of tensile fracture morphology shows that tearing strips and dimples much occurs in the fracture of Al-20Si alloy treated by high intensity ultrasonic treatment,characterized by mixed fracture of brittle and toughness crack.
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发布时间：2023-12-18 - 摘要：Microstructure and properties of Mg-6Zn ribbons with different Ca addition prepared by two-roll rapid solidification were investigated by OM,SEM,XRD and DSC as well as micro-hardness tester. The results indicate that besides rapid solidification can greatly refine primary phase and secondary phase,Ca can give a help for refining further microstructure of the alloy too. The microstructure of the rapidly solidified Mg-6Zn alloy ribbons are composed of supersaturated α-Mg,Mg51Zn20 phase and a little Mg2Zn3 and MgZn2 phase. With increasing in Ca addition,Mg2Ca,Ca2Mg6Zn3 and MgZn2 phase are gradually increased with the decrease of Mg2Zn3 and Mg51Zn20 phase,which is beneficial to improving the thermal stability of the alloy.关键词：Rapidly Solidified Ribbons;Mg-6Zn-xCa Alloy;Microstructure;Thermal Stability
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发布时间：2023-12-18 - 摘要：By testing the thermal process of copper scrap smelting system and analyzing operation status of equipment,the problems existed in low oxidized copper rods production were found as follows:poor fuel quality,irrational burner structure,low metal recovery rate and high impurity in products. To eliminate these problems,a set of gravity duster separator with purification and water seal integrated is employed to improve the fuel-gas quality,the high-velocity spiral burners are used to enhance the combustion efficiency and the temperature uniformity in the furnace,low-temperature slag skimming technology is applied to prevent the ferrous impurities into the liquid copper,and temperature control during oxidation-reduction period technology is adopted to improve copper percentage recovery and product quality,shortening smelting cycle. Through above mentioned measures,the energy consumption and copper loss in the copper scrap smelting process are reduced,and quality of copper rods is improved,and the properties of low-oxidized copper rods such as elongation and torsion are superior to industry standard,moreover,pollution of scrap-gas on environment is relieved.关键词：Reclaimed Copper;Reverberatory Furnace;Smelting;Energy-Saving
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发布时间：2023-12-18 - 摘要：Large Al bronze bush was produced by centrifugal casting. Matching relationship between equipment parameters and mould parameters,between mould parameters and bush parameters as well as among centrifugal casting parameters were described in condition of limited state of centrifugal machine. Possibility of centrifugal casting for mould with occurrence of offcenter was discussed during process. Meanwhile,prevention of defects in centrifugal casting large Al bronze bush was introduced.关键词：Al Bronze;Centrifugal Casting;Large Bush;Parameters Matching
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发布时间：2023-12-18
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