ZHANG Bao-yan, CHEN Xiang-bao, ZHOU Zheng-gang. Influence of Air Release Additive on Quality and Properties of Vacuum-bag Cured Composite[J]. Journal of Materials Engineering, 2007, 0(12): 3-7.
The principle of air bubbles in the resin removed by air release additive was analyzed,and the influence of air release additive BYK ζ-A560 on the quality and properties of vacuum-bag cured VB-90/T700 composite was investigated.Results indicated that the quality of VB-90/T700 composite laminates was improved significantly by incorporating BYK ζ-A560,the laminates manufactured from BYK ζ-A560 incorporated VB-90/T700 prepreg had autoclave cure quality with excellent mechanical properties.BYK ζ-A560 had no negative influence on the heat resistance of VB-90/T700 composite,and the BYK ζ-A560 incorporated VB-90/T700 composite could be serviced as high as 90℃ as a structure material.A novel vacuum-bag curable prepreg with promising characteristics is being developed.
XIA Peng-cheng, YU Wen-fang, YU Jin-jiang, SUN Xiao-feng, GUAN Heng-rong, HU Zhuang-qi. Influence of Long-term Thermal Exposure on γ′Phase of DZ951 Alloy[J]. Journal of Materials Engineering, 2007, 0(12): 8-11.
Microstructure evolution of directionally solidified DZ951 nickel-base superalloy during long-term exposure was investigated.The results show that γ′phase coarsens and rafts with the rise of aging temperature and time.The time of γ′rafting decreases with the increase of aging temperature.The driving force of γ′rafting is the drop of elastic strain energy and interface energy.γ′growth is controlled by diffusion of element and obeys LSW rule.The activation energy of γ′growth is about 294kJ/mol.The γ′stability is improved because there are some high melting elements such as W,Mo,Nb in γ′phase,which increases the activation energy of γ′growth.There are not harmful phases such TCP phase etc in DZ951 alloy during long-term aging,which shows that the alloy has good microstructure stability.
ZHAO Jin-qian, LI Jia-rong, LIU Shi-zhong, HAN Mei. Transverse Tensile Properties of Second Generation Single Crystal Superalloy DD6[J]. Journal of Materials Engineering, 2007, 0(12): 12-14,20.
At 800-950℃,the transverse tensile properties of the second generation single crystal superalloy DD6 were investigated.The results show that the transverse ultimate tensile strength decreases with temperature increasing.The transverse elongation increases first,then markedly decreases with temperatures increasing,and at higher temperatures the transverse elongation is clearly less than the longitudinal elongation.It is considered that the microcracks are apt to form on the dendritic interfaces with temperature increasing,as leads to plasticity decreasing.
WEN Zhi-xun, YUE Zhu-feng, ZHU Zhen-tao. Fracture Behaviour of Compact Tension Specimens of Nickel-based Single Crystal Under Tension Creep and Cyclic Loading[J]. Journal of Materials Engineering, 2007, 0(12): 15-20.
The fracture behaviour of compact tension(CT) specimens of nickel-based single crystal superalloys DD3 was studied at 950,850,760℃.The creep and fatigue property was investigated at 950℃.Three crystallographic orientations , and of the specimens were considered.The macro crack growth and micro characterization of the fracture surfaces were examined by the optical microscope(OM) and scan electron microscope(SEM).The tension experimental results show that the macro crack growth path takes place in specific vectors and appears to be in a zigzag manner.The temperature has much influence on fracture behaviour.At low temperature(760℃),the fracture mode is pure shear fracture and belongs to brittle mode.But at high temperature(950℃),fracture mode turns to be microvoid coalescence fracture and belongs to ductile mode.The creep and fatigue properties of CT specimens are obviously anisotropic.Creep life decreases in the order of ,, and fatigue life decreases in the order of ,, under same test conditions.The creep and fatigue crack growth path is perpendicular to the loading axis.It is found by SEM that there are much cup-cone dimple on the creep fracture and typical fatigue striations on the fatigue fracture surface.The fracture damage can results in crack growth more easily than creep damage.
HUANG Guang-jie, QIAN Bao-hua, YOU Hong. Functions Correlating Tensile Peak Stress and Deformation Stored Energy of 45 Steel at Elevated Temperature with Zener-Hollomon Parameter[J]. Journal of Materials Engineering, 2007, 0(12): 21-25.
In order to research on correlative functions of peak stress and deformation stored energy with Zener-Hollomon parameter,the elevated temperature tensile test of 45 steel was carried out at Gleeble-1500D thermal-mechanical simulator,in the range of deformation temperature 1123-1273K and initial strain rate 0.01-5s-1.And a hyperbolic sine model was also introduced.The results indicate that the hyperbolic sine relationship can satisfactorily describe the correlation between peak stress and Zener-Hollomon parameter with the activation energy of 336.0kJ/mol,while the constitutive relationship of deformation stored energy with ZenerHollomon parameter can be represented by an equation of ΔGD=0.1269(lnZ)2-6.8262(lnZ)+93.873.Furthermore,the value of deformation stored energy increases with the decreasing of deformation temperature as well as the increasing of strain rate and fluctuates within the range of 2-20J/mol.
YANG Sheng, YI Dan-qing, YANG Shou-jie, ZHONG Li. Effect of Corrosive Environment on Fatigue Crack Propagation of 2E12 Aerospace Aluminum Alloy[J]. Journal of Materials Engineering, 2007, 0(12): 26-29,34.
The fatigue crack growth behavior of 2E12 aluminum alloy was studied in air,humidity air and 3.5%(mass fraction)NaCl salt fog by SEM,TEM and fatigue property testing.The results showed that the fatigue crack growth of 2E12 was better than that of 2524 aluminum alloy.The growth rates of fatigue crack in different environments,were analyzed and compared by Paris equation.Fatigue crack growth rates in salt fog was highest,somewhat less in humidity air and lowest in air.Furthermore,the fractographic features such as small crystallographic face of micro-crack growth,fatigue striation of macro-crack growth and microstructure of shear zone reflected the fatigue crack growth behavior of alloy in a given environment,more brittle striations were observed in humidity air and salt fog.The increased crack growth rates was due to a combination of hydrogen embrittlement and anodic dissolution at the crack tip.
ZHAO Jin-long, DENG Jian-xin, SONG Wen-long. Optimization of Substrate Materials and Preparation of MoS2 Coated Tools[J]. Journal of Materials Engineering, 2007, 0(12): 30-34.
Stresses due to thermal mismatch between coating and substrate developed in MoS2-based coatings when cooled down to room temperature from deposition temperature.A 2D finite element model(FEM) for coating substrate system was established to simulate and analyze thermal mismatch stress.Results show that mismatch of coefficient of thermal expansion and Young’s modulus is significant to thermal stresses,while Poisson’s ratio and thermal conduction coefficient have little influence on them.The effects of deposition temperature on the residual stress were also analyzed.MoS2 coatings composited with Zr were deposited by medium-frequency magnetron sputtering technique on the selected substrates and the properties tested proved the analysis of FEM.
HAN Zheng-tong, ZHANG Ning-ju, GAO Ding, CHEN Dong-mei. Experimental Research on Grinding Hardening for Quenched and Tempered 40Cr Steel[J]. Journal of Materials Engineering, 2007, 0(12): 35-38.
This paper tried to carry out test study on grinding hardening of 40Cr steel.Through carrying out the grinding experiments with variable cut depths and feed speeds,the grinding force and the specific grinding energy were analyzed.Furthermore,the changing law of depth of hardening layer was studied,and the metallographic structure of testpiece was analyzed,it showed the feasibility of grinding hardening for 40Cr steel.
SONG Wen-long, DENG Jian-xin, ZHANG Hui. Preparation of MoS2/Zr Composite Coating and Its Performance[J]. Journal of Materials Engineering, 2007, 0(12): 39-43,47.
The complex deposited process which fitted medium-frequency magnetron sputtering together with multi-arc ion plating,was utilized to prepare the MoS2 /Zr composite coating on the surface of cemented carbides YT14.SEM was adopted to observe and analyze the surface and cross-section morphologies of composite film.EDX was used to analyze the surface and cross-section component of the composite film.The thickness and hardness and adhesion strength of coating film were tested.The results show that the structure of MoS2 /Zr composite film is dense,the adhesion strength is about 60 N,the thickness is about 2.6μm,and the hardness is about HV800.
ZHU Li-hui, LIU Wei, LI Tai-chang, HUANG Qing-wei. Effect of Plate-like Alumina Seed Amount on Microstructure and Properties of Alumina Ceramics[J]. Journal of Materials Engineering, 2007, 0(12): 44-47.
The effects of plate-like alumina seed amount on the microstructure and properties of alumina ceramics prepared by pressureless sintering were studied,when plate-like alumina single crystal particles were used as seeds and CaO-Al2O3-SiO2(CAS) were used as additives.The additions of both α-Al2O3 platelets and CAS lead to the development of elonged grains.More and more elonged grains are formed with the increase of seed addition.However when 60%(mass fraction) seeds are added,the size of elonged grains decreases in spite of more elonged grains.The relative density and hardness of alumina ceramics are hardly affected by the addition of plate-mike alumina seeds,but the fracture toughness increases first and then decreases with the increase of seed addition.When 30% seeds are added,the fracture toughness reaches a maximum(6.5MPa·m1/2).Compared with the sample without the addition of seeds,the fracture toughness increases by 25%.
YAN Chun-ze, SHI Yu-sheng, YANG Jing-song, LIU Jin-hui, HUANG Shu-huai. Nylon12/Copper Composite Powder for Application in Selective Laser Sintering[J]. Journal of Materials Engineering, 2007, 0(12): 48-51.
Nylon12-coated copper powder composite was prepared by solvent-precipitation method.Microcosmic appearance of the composite was observed using SEM.The strength and warpage behavior of the selective laser sintered parts of nylon12-coated copper powder and mechanically mixed nylon12/copper powder were compared.The results show that nylon12 coats the particles of Cu powder evenly and there is hardly bared particle of Cu powder in the nylon12-coated copper powder.At the same nylon12 mass fraction of 20% and laser energy density,the tensile strength and flexural strength of green parts made from coated copper powder are both about twice higher than those of parts made using mechanically mixed nylon12/copper powder,and the warpage degree of green parts of nylon12 coated copper powder is obviously smaller than that of parts made from mechanically mixed nylon12/copper powder.
JI Fang, FENG Ke-qin, YANG Yi, LIAN Shan-shan, WU Jin-ling. Effects of Technologic Parameters on Combustion Synthesis of Fe-Ti-C System Under Action of an Electric Field[J]. Journal of Materials Engineering, 2007, 0(12): 52-57.
Using the thermal simulation instrument Gleeble,the effects of technologic parameters such as pressure and the process of heat preservation on combustion synthesis of Fe-Ti-C system under the action of an electric field were studied.A series of research,such as temperature analysis on combustion synthesis of the system and X-ray diffraction(XRD) analysis and scanning electron microscope(SEM) analysis of products,show that both the ignition temperature and the highest temperature of the compact with heat preservation at 200℃ are higher than that of the compact without heat preservation,the products of the compact with heat preservation at 200℃ consist of TiC and Fe.However,the products of the compact without heat preservation consist of TiC,Fe and a little Fe2Ti.The size of the compact with heat preservation at 200℃ is smaller than that of the compact without heat preservation,a small pressure will cause the decreasing of ignition temperature and small size of TiC,the pressure has a little influence on products.
ZHANG Guo-bing, GUO Quan-gui, LIU Lang, SHI Jing-li, ZHAI Geng-tai, SONG Jin-ren. Preparation and Properties of B4C/C Functionally Graded Material by Hot-press Sintering[J]. Journal of Materials Engineering, 2007, 0(12): 58-62.
Crack-free five-layered B4C/C functionally graded material(FGM) was designed and fabricated by a powder stacking method and hot-pressing process under pressure of 40MPa at 2000℃ with B4C content changing from 10%(mass fraction) to 50%.Furthermore, in order to study the properties of graded layers of B4C/C FGM,the corresponding B4C/C homogeneous composites were fabricated under the same conditions.The structure and some properties of B4C/C homogeneous composites and FGM were analyzed.The results show that the density,strength,electrical resistivity and oxidation resistance of the homogeneous composites are all improved with the increase of B4C content.B4C/C FGM whole has low density and high bending strength,2.16g/cm3 and 138MPa,respectively.SEM micrographs and XRD patterns show that the structure of the FGM has the excellent gradient characteristic.The oxidation experiment shows that the oxidation resistance of the FGM also has the same characteristic,and would be used for the oxidation resistance or plasma facing component field.
LI Cheng-liang, HAO Shao-chang, ZHAO Xing-yu, GUO Wen-li, LIANG Tong-xiang. Gel-casting Preparation of Ceramic ZrO2 Composition Microspheres[J]. Journal of Materials Engineering, 2007, 0(12): 63-66.
ZrO2 ceramic microspheres were preparaed by gel-casting.The influences of dispersant,initiator and vacuum deairing on the property of ZrO2 ceramic slurry were studied.The results show that the advantages of putting catalyst into organic oil is that the slurry can be kept for much longer time and the temperature of organic oil can be decreased from 90℃ to 50℃.Well-size-distributed ZrO2 microspheres can be realized by applying vibration dispersion technology.
NIE Shu-hong, XIONG Shou-mei. Experimental Study on Melting AZ91D Magnesium Alloy in a Sealed Furnace Under MgF2/N2/Air Protective Atmospheres[J]. Journal of Materials Engineering, 2007, 0(12): 67-72,78.
The effects of holding temperature and air content in the atmosphere on the protection of AZ91D magnesium alloy were investigated in a sealed furnace enclosed solid MgF2 before the experiments.The morphology,ingredients,and ingredient distribution of the surface film were also studied.The results showed that the AZ91D specimens were not gradually protected with the increase of holding temperature and content of air in the atmosphere;AZ91D specimens were well protected under atmospheres containing 25%(volume fraction) air below 750℃;AZ91D specimens were also well protected under atmospheres containing <30% air at 650℃.All the surface films were made up of the MgF2 and MgO,the thickness of all the surface films increased with the increase of the holding temperature and the air content in the atmosphere,the MgF2 content in the surface film also increased. The surface of film became uneven with the increase of air in the atmosphere and there was no obvious influence of the holding temperature on the flatness of the surface film.Since solid MgF2 had a high vapor pressure at the melting temperature,the Mg reacted with the O2 in the atmosphere,the MgO and MgF2 formed the surface film on AZ91D.
LI Li, WANG Bao-hui, TONG Mao-song. Progress in Characteristics and Application of One-dimensional V2O5 Nanomaterials[J]. Journal of Materials Engineering, 2007, 0(12): 73-78.
This review describes some recent developments in electrical,magnetic,electrochemical and optical properties of various vanadium pentoxide nanostructures including nanowires,nanorods, nanotubes,nanobelts as well as their application in sensors and actuators,field effect transistors(FET),metal-insulator-semiconductor(MIS) structure,electrodes of Li-ion battery,super electrochemical capacitors,electrochromic display devices and nanolithography templates.The trends of one-dimentional V2O5 nanomaterials in the future is also discribed.
