YU Mei, LIU Jianhua, LI Songmei, XU Liang. Fabrication of Ni Coatings on Glass Microspheres and Electromagnetic Properties[J]. Journal of Materials Engineering, 2009, 0(6): 1-4.
Ni/glass microspheres composite powders with conductive and magnetic properties were fabricated successfully by electroless plating of Ni alloy thin coatings on glass microspheres.X-ray diffraction(XRD),scanning electron microscopy(SEM) and energy disperse spectrometry(EDS) were used to characterize the crystalloid structure,topography and component of non-coated and coated glass microspheres.It is shown that a uniform Ni coating with the thickness at about 0.2μm is coated on glass microspheres after electroless plating.The Ni coating has face-centered cubic structure.The permittivity and permeability of non-coated and coated glass microspheres were tested by the waveguide method in 8-12GHz.It is concluded that electromagnetic loss properties of the coated glass microspheres have been greatly improved.
WANG Wenhe, SHEN Shiming, YU Xiaochun. Experimental Study on Material Corrosion Behavior and Mechanism for 20# Pipeline Steel in Near-neutral Soil[J]. Journal of Materials Engineering, 2009, 0(6): 5-9,14.
Corrosion process and mechanism of 20# low-carbon steel in near-neutral in soil are studied by experiments of buried specimens in laboratory.In three kinds of soils,the corrosion features and products are analyzed by EDS and XRD,and the relation of corrosion rates,open-circuit potential and polarization curve with times are tested.The results indicated that corrosion rates changed incessantly along.On the condition of the same times,specimens and different soil samples,the corrosive degree of 1# and 2# specimens are serious,but 3# specimen is a little serious.The corrosion products are main non-crystalloid,Fe(OH)3 and Fe2O3.The change rules of different times and soils are different,and are accordant with that of corrosion rates.The corrosion mechanism is discussed,in near-neutral soils,oxygen is deoxidized and OH-ions are created in cathode area,iron is oxidized and the hydration of Fe2+ ions is created with water from soil in anode area,and Fe2+ are converted into more steady products Fe(OH)3 and Fe2O3.
CHEN Bo, XIONG Huaping, MAO Wei, CHENG Yaoyong, GUO Wanlin. Microstructure and Property of SiCf-reinforced Titanium Based Composite Joint Using Ti-Zr-Cu-Ni Brazing Filler[J]. Journal of Materials Engineering, 2009, 0(6): 10-14.
The vacuum brazing test of SiCf/β21S titanium matrix composite was carried out and the mechanical property was investigated.The results indicate that the shear strength of the SiCf/β21S joints brazed under 960℃/10min is 97.9MPa.However,the joint strength under the brazing condition of 960℃/10min/5MPa is increased to 303.7MPa.The joint strength is mainly affected by the amount of brazing defects and brittle compounds of Ti(Zr)-Cu(Ni,Co) in the joints.
NIE Xianghui, LI Xiaogang, DU Cuiwei, SHEN Qinghong. EIS Analysis of Q235 Corrosion in Sea-shore Salt Soil with Different Water Contents[J]. Journal of Materials Engineering, 2009, 0(6): 15-19.
Corrosion Behaviors of Q235 in sea-shore salt soil with different water contents were studied by EIS technique.The results indicate: the corrosion of Q235 in 10% water content soil was controlled by anodic reaction,while in soils with 20% and 34% water contents,it was controlled by diffuse step in cathodic reaction.In 10% water content soil,being the increasing of pitting depth and area,the admittance of constant phase angle element Qdl-Y0 increased with time.In 20% and 34% water contents soils,being the decreasing of oxygen concentration on the surface of sample,the admittance of Warburg impedance decreased gradually.With time increasing,the balance of oxygen diffuse and reduction reaction achieved,the oxygen concentration on the surface of the sample and the admittance of Warburg impedance tended to be stable.
LI Jianfeng, ZHOU Tietao, YAN Ping, ZHAO Jingchen, LIU Peiying, HAN Fengkui. Effects of Section Sizes on Microstructure of a Nickel-base Single Crystal Superalloy[J]. Journal of Materials Engineering, 2009, 0(6): 20-25.
Effects of section sizes on microstructure of a nickel-base single crystal superalloy have been studied by making directly thin-wall specimens whose wall thicknesses are 0.8,1.5mm and 2.5mm by using the Bridgmen procedure.The results show that,with the decrease of section size,the primary dendritic arm spacing of thin-wall specimen decreases,and the secondary dendritic arm spacing increases firstly and then decreases;comparing with the standard specimen(φ15mm),the size of γ′phase particles in the dendritic core decreases but that of interdendritic changes slightly,the volume fraction of γ/γ′eutectic also decreases obviously.EDS analysis shows that microsegregation of thin-wall specimens has been suppressed comparing with the standard specimen,but the microsegregation of specimens with different thickness isn’t obvious.Furthermore,γ/γ′ eutectic of thin-wall specimens was ruled out basically after vacuum solid-solution treatment,but for φ15mm specimen there remains a small amount γ/γ′eutectic.
LI Bin, SHI Hua, ZHANG Xiaoyun, TANG Zhihui, YU Bo. Study on Phisical-chemical and Performance Properties for YTF-1 Aircraft Water Displacing Corrosion Preventive Compound with Hard Film[J]. Journal of Materials Engineering, 2009, 0(6): 26-29.
The comprehensive physical-chemical and some performances properties for YTF-1 aircraft water displacing corrosion preventive compound with hard film were studied and compared with the overseas product XX.The results show that YTF-1 had satisfied properties of spray ability,functional penetration and synthetic sea water displacement.The film of YTF-1 had advantages of coating transparency,removability,low-temperature adhesion,low temperature flexibility,high temperature flow,water immersion resistance and ultraviolet ray resistance.
ZHAO Jie, LI Dongming, FANG Yuanyuan. Selection of Manson-Haferd Constants and Its Application on Rupture Life Prediction[J]. Journal of Materials Engineering, 2009, 0(6): 30-34.
Manson-Haferd method is selected for rupture life prediction by comparing with Larson-Miller method.It indicates that the change of Larson-Miller constant C has obvious effect on the predicting result of rupture life.While for Manson-Haferd method,the constants(Ta,lgta) are not independent variables,but exhibit linear relationship.Different Manson-Haferd constants(Ta,lgta) shows a good prediction results.Application of the same Manson-Haferd constants(450,15) results in a good prediction tendance.
WANG Yanli, HUANG Zhaohui, ZHANG Qiang, TAN Yongning, ZHANG Hongwei, JIA Xinyun, ZHAO Xihong, LI Jiarong. Effects of Chemical Compositions on Hot Tearing of Directionally Solidified Alloys[J]. Journal of Materials Engineering, 2009, 0(6): 35-38.
Effects of the elements,such as Ti,Zr,Hf,Al and B on hot tearing susceptibility during directional solidification were investigated by tube-like directional samples with thickness of 1.0mm in walls.The results of SEM,DSC and fracture analysis of the elements on the solidification of the alloys were presented.It is found that titanium promotes the formation of γ/γ′eutectic,increases its sizes,moreover changes the solidified temperature range of alloys,which leads to crack formation and poor castability.Increasing Zr content promotes eutectic and enlarges hot tearing.During directional solidification changing Hf content can hardly result in the hot tearing of alloys.Increasing Al or B content shows only a little microstructural evolution but enlarges the solidified temperature ranges of alloys,thus alloys with a strong tendency to hot tearing.
MA Guojun, ZHAO Xinqing. Structural Transition of Metastable Co Particles Under Stress[J]. Journal of Materials Engineering, 2009, 0(6): 39-42.
The metastability of Co fine particles with sub-micrometer and micrometer scale was investigated by cooling from high temperature and by applying external stress.The structural transition features of the Co particles were characterized by scanning electron microscope,X-ray diffractometer and vibrating sample magnetometer.It is found that during the cooling from high temperature the Co fine particles within in a wide size range keep their high temperature structure(FCC) to room temperature or cryogenic temperature.However,these metastable Co particles are very susceptible to the applied stress,and under the external stress these metastable Co particles easily transform to stable HCP structure at room temperature upon martensitic transformation induced by stress.The size effect on metastability of Co particles was discussed based on the influence of the surface tension on the martensitic transformation.
JIA Panjiang, CHEN Bangfeng. Effect of Casting Temperature on the Mechanical Properties and Microstructures of the ZL210A Casting Aluminum Alloy[J]. Journal of Materials Engineering, 2009, 0(6): 43-45.
The effect of different casting temperatures on the mechanical properties,microstructures and fracture surfaces of the ZL210A casting aluminum alloy was investigated.The result shows that casting temperatures have no influence on the tensile strength,hardness and fracture surfaces of the ZL210A alloy and a little influence on the elongation.The eutectic phase on grain boundary increases as casting temperature increasing.Phase constituents of as-cast alloy were composed of α(Al) and θ(Al2Cu) phase.
JI Ling, WANG Yumin, SHI Nanlin. TEM Analysis of Interface in SiC Fibre Reinforced Aluminium Matrix Composite Prepared with Semi-solid Diffusing Method[J]. Journal of Materials Engineering, 2009, 0(6): 46-50.
A novel processing called semi-solid diffusing(SSD) method was used to manufactured CVD SiCf /Al(5A02) composite.The interface reactions and the products were compared with that of specimen manufactured by solid diffusing bonding(SDB) method.In the case of specimen manufactured with SSD method,an interface without Al4C3 formed and some MgO particles were detected.However,in the specimen manufactured with SDB,Al4C3 formed and grew into the matrix from the Al2O3 film attached on the carbon coating,which destroy the continuity of interface.Because Mg enriched around the surface of SiC fiber and MgO was formed,the diffusion of C in the interface was decreased and the forming of brittle Al4C3 was restricted,which was beneficial to control the negative reaction of interface.
JIANG Shaosong, ZHANG Kaifeng, WU Haifeng, XU Yi, LEI Kun, WANG Bin. Preforming-die Design and Friction Changing to Control the Thickness Distribution of TC4 Deep Cylinder by Superplastic Forming[J]. Journal of Materials Engineering, 2009, 0(6): 51-55.
Based on the direct-reverse superplastic forming TC4 deep cylinder with uniform thickness(thickness accuracy: 1.6mm±0.2mm),different shapes of preforming-die were designed and the influence of the shape on the thickness distribution of cylinder was investigated using MSC.MARC.And also the influence on final thickness distribution of surface friction of preforming die and forming die was analyzed.The results show that the thinning of the blank near the periphery and the bottom of deep cylinder benefits to the uniform thickness of the side wall.And higher friction coefficient of preforming die can efficiently reduce the thickness of the regions which need to be thinned,results in a more uniform final thickness distribution along the component.Lower friction coefficient of forming die can make the sheet tend to integral formation,also results in uniform thickness distribution.According to the results of the FEM,the surface of performing die and forming die was treated and the aerospace TC4 deep cylinder was fabricated successfully by direct-reverse superplastic forming,the thickness of the cylinder meet the need of 1.6mm±0.2mm.
HU Yong, YAN Hong, CHEN Guoxiang. Semi-solid Microstructure Evolution of In situ Synthesized Mg2Si/AM60 Magnesium Matrix Composites[J]. Journal of Materials Engineering, 2009, 0(6): 56-59.
Mg2Si/AM60 composites were fabricated by in situ synthesis and the effects of different stirring technologic parameters to the microstructures of semi-solid magnesium matrix composite were investigated.The results indicated that there were Chinese script type Mg2Si particles in the microstructures by addition crystal Si to the magnesium alloys.The mechanical stirring were used to fabricate the semi-solid composite and the results showed that the higher of stirring temperature and stirring speed,the finer and more homogeneous the spherical grains.If the temperature is too high,the grains will be melted.With the increasing of stirring time,the grains become fine,well-distributed and round at first,then grow up.
HU Yuhua, XUE Songbai, CHEN Wenxue, WANG Hui. Investigation on the Wettability and Interfacial Structure of Sn-9Zn-xAg Solders on Cu Substrate[J]. Journal of Materials Engineering, 2009, 0(6): 60-63.
The effect of Ag addition in Sn-9Zn solder on its microstructure and wettability was investigated,and interfacial structure of solder/Cu was also examined.Results show that,when the addition of Ag is lower than 0.3%,the needle-like Zn-rich phases decrease gradually.But when the content of Ag is between 0.5% and 1%,Ag-Zn intermetallic compounds appear in the solders.When the content of Ag is 0.3%,the solder presents the best wettability.When the content of Ag reaches 0.5%-1%,the wettability decreases.Intermetallic compound formed at the Sn-Zn/Cu interface is a planar layer(Cu5Zn8).As for the Sn-Zn-0.3Ag/Cu interface,additional nodules(AgZn3) are visible beside the aforementioned planar layer.And the additional nodules grow up to a scalloped layer gradually as the content of Ag increases.
YANG Liuqing, KANG Yonglin, ZHANG Fan, TAO Tao, DING Ruihua. Study on Microstructure-processing Relationship of a Semi-solid Rheo-diecasting A357 Aluminum Alloy[J]. Journal of Materials Engineering, 2009, 0(6): 64-66,72.
A semi-solid preparing and rheomoulding apparatus which self-developed for light alloys in laboratory is introduced.It mainly consists of a melting furnace,a shearing system with two relative-rotating conical barrels,a central temperature control unit,gas protection system,conveying appliance and a die-casting system.Microstructure-processing relationship of A357 aluminum alloy obtained by the apparatus was investigated.Solidification behavior of the semi-solid rheo-diecasting processing was discussed.The results show that the apparatus is capable of eliminating coarse dendrites,and producing small and spherical solid particles uniformly distribution in a eutectic matrix.In addition,the process can eliminate entrapped gas and reduce fine shrinkage pores in the specimens as well.The primary α1-Al particles will become rounding with the increase of shear rate.During the SSM slurry preparing,the primary α1-Al particles is formed firstly.Secondary solidification of the slurry takes place in the die-casting process.
TAO Jingmei, HUANG Suzhen, XU Mengchun, LI Caiju, ZHU Xinkun. Study on the Mechanical Properties of Pure Bulk Al with Nanocrystalline[J]. Journal of Materials Engineering, 2009, 0(6): 67-72.
Pure bulk Al with grain size in the range of nano scale was prepared through high energy ball milling using pure Al powder as raw material,and samples prepared with different milling parameters including milling time and milling ratio,etc.were compared.The grain size and mechanical properties of pure bulk Al after ball milling were measured by means of XRD and microhardness tester,and the relationship between the average grain size and the microhardness was also investigated.As the results show,the average grain size of the samples are in the range of 47 nm to 66 nm after ball milling,and the microhardness of the samples increases first and then decreases and at last increases again with the elongating of ball milling time,and the microhardness of the samples reaches the maximum value when the ball milling time is 5h.The yield strength and the grain size accord with the Hall-Petch relation.
FAN Limei, SHI Yiwei, REN Jilin. Application of Multizone Ultrasonic Inspection for Great Thickness EBW[J]. Journal of Materials Engineering, 2009, 0(6): 73-77.
In the purpose of inspecting great thickness EBW,multizone focused inspection technique was applied.The results of sensitivity testing on the defect specimen were showed: the sensitivity was achieved φ0.4mm flat bottom holes and signal to noise ratio(S/N) was achieved above 9dB beyond 70mm,it achieves the demands of ultrasonic inspection;The signal to noise ratio(S/N) is poor with immersion flat transducer inspection and contact method using longitudinal wave,not achieving the demands of ultrasonic inspection.φ0.4-15dB small defect was discovered with multizone ultrasonic inspection technique beyond 60mm.and the sensitivity was better than X-ray.So multizone focused inspection was effective for quality evaluation of great thickness EBW.
ZHANG Linwei, WEI Qi, LI Hui, LI Zhuoxin. Oxidization Behavior of Thermally Sprayed Particles and the Relevant Protective Techniques[J]. Journal of Materials Engineering, 2009, 0(6): 78-82.
Thermally sprayed coatings are built up by successive impacts of molten or semi-molten particles on substrates or previously formed under-layers.The oxidation behavior of thermally sprayed particles can significantly influence the phase composition,the microstructure and the overall performance of the sprayed coatings.The oxidation mechanism of thermally sprayed particles during spray process and the protective techniques reducing the oxidation of thermally sprayed particles are reviewed.
