2015 Vol.35(1)

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2015, 35(1): 0-0.
[Abstract](79) [PDF 2539KB](1)
Effects of Cooling Rate and Holding Time on Microstructure and Property of TLP Bonded Joints for DD3 Single Crystal Superalloy
Xiao-hong LI, Lei YE, Qun-peng ZHONG, Chun-xiao CAO, Wei MAO
2015, 35(1): 1-7. doi: 10.11868/j.issn.1005-5053.2015.1.001
[Abstract](204) [FullText HTML] (33) [PDF 4311KB](1)
Transient liquid phase (TLP) bonding of DD3 single crystal superalloy at 1250℃ with different holding time was studied. Two cooling methods such as furnace-cooling (FC) and Ar-quench cooling (AC) were adopted. An aging treatment with 870℃/32h/air cooling was performed after the welding process. Microstructures of bonding seams and base metals with different welding conditions were observed and stress-rupture properties at 980℃ of the joints were tested. The results show that the size of γ'phases of bonding seams and base metals by FC increases with holding time, and the shape becomes irregular. While when AC method is used, the size and shape of γ'phases are not changed with holding time and γ'phases are still fine and cube-like. Low cooling rate makes γ'phases of welding seams and base metals become bigger, which leads to the deterioration of mechanical properties of the joints and base metals. On the other hand, high cooling rate makes fine and cube-like γ'phases, which increases the mechanical property of the joints, and ensures the property of the base metal is maintained.
Effects of Alumina Particles Morphology on Properties of Silica-based Ceramic Cores
Li-li WANG, Jia-rong LI, Ding-zhong TANG
2015, 35(1): 8-12. doi: 10.11868/j.issn.1005-5053.2015.1.002
[Abstract](202) [FullText HTML] (31) [PDF 2318KB](1)
Silica-based ceramic cores with alumina as mineralizer were prepared and the effects of particle size and shape on properties of ceramic cores were studied. The results show that the slurries with spherical alumina particles fill mold better than those with the irregular ones. When irregular alumina particles are added, the sintering shrinkage of ceramic cores decreases with the increase of particle size. When spherical alumina particles are added, the particle shape or size has slight influence on the sintering shrinkage and flexural strength of ceramic cores at room temperature; while the resistance to deformation at high temperature is significantly weakened.
Plastic Deformation Behavior of TA7 Titanium Alloy
Yun-peng DONG, Qiu-ying YU, Shuang FANG, Shu-yun WANG, Chao-yuan WANG, Xiao-jun SONG
2015, 35(1): 13-19. doi: 10.11868/j.issn.1005-5053.2015.1.003
[Abstract](216) [FullText HTML] (52) [PDF 3482KB](2)
The flow stress of TA7 titanium alloy was investigated by isothermal hot compression in the temperature range of 850-1000℃ and strain rate of 0.001-0.1s-1. The constitutive equation for describing the plastic deformation behavior of the TA7 titanium alloy during hot compression process was deduced. The results show that the flow stress of the TA7 titanium alloy is greatly affected by temperature and strain rate. With the increase of the temperature and decrease of the strain rate, the flow stress of the TA7 titanium alloy decreases greatly, and the plastic deformation get into the steady-going condition state immediately under the condition of low flow stress.
Surface Corrosion Behavior of PbSe Films
Ye TIAN, Da-bo LIU, Fei LUO, Hong-fei QI, Yong LIU, Bo CHENG, Le-jin TENG
2015, 35(1): 20-24. doi: 10.11868/j.issn.1005-5053.2015.1.004
[Abstract](179) [FullText HTML] (42) [PDF 1719KB](1)
PbSe films were prepared by RF magnetron sputtering, and subsequently subjected to the chemical etching in dilute H2O2 solution. The morphology, structure and optical properties were characterized by SEM, XRD and UV/Visible absorption spectrophotometry, while the photoconductivity was also investigated. Results show that a series of novel nanostructures surfaces are found to be appeared in the epilayer. In the meanwhile, the photoconductivity of PbSe films is significantly improved after the H2O2-solution treatment. It is expected that this work offers a simple way to improve PbSe-based optoelectronic device performance.
Hot Deformation Behavior and Processing Maps of Al-17.5Si-4Cu-0.5Mg Alloys
Run-xia LI, Lei ZHANG, Lan-ji LIU, Li-jun ZHANG, Yan-hua BAI, Rong-de LI
2015, 35(1): 25-32. doi: 10.11868/j.issn.1005-5053.2015.1.005
[Abstract](177) [FullText HTML] (42) [PDF 3779KB](1)
Hot compression tests of Al-17.5Si-4Cu-0.5Mg alloy were carried out at 350-500℃ and strain rates of 0.001-5s-1 on a hot-simulation machine Gleeble-1500D to study the hot deformation behavior and hot working property. Results show that the Al-17.5Si-4Cu-0.5Mg alloy is a positive strain rate sensitive material; the flow stress of this alloy can be described by the hyperbolic sine equation during high temperature deformation; the average thermal deformation activation energy Q is calculated to be 308.61kJ/mol. The processing maps were calculated on the basis of the dynamic materials model (DMM). The optimum processing parameters are determined by combining processing maps and microstructure evolution analysis. The deformation temperature are in the range from 400℃ to 470℃ and the strain rate is around 0.1s-1.
Microstructure and Mechanical Properties of FSW Joints between Dissimilar High-strength Aluminum Alloys
Fan WANG, Zhan FANG, Chen XU, Yu-huan YIN, Ke CHEN
2015, 35(1): 33-38. doi: 10.11868/j.issn.1005-5053.2015.1.006
[Abstract](233) [FullText HTML] (50) [PDF 3121KB](1)
2195-T8 and 2219-T87, the two widely used high-strength aluminum alloys in aerospace industry, were successfully joined together by friction stir welding (FSW). The variation of microstructure and mechanical properties with different travel speeds was studied at a fixed tool rotation speed. Distinct interface was observed at the top part of weld nugget, and the morphology of this interface was influenced significantly by travel speed. Meanwhile, a new fracture mode of FSW joint was discovered at high travel speed. The fracture mode is related to the morphology and metallurgical bonding strength of the interface between dissimilar materials at the top part of weld nugget. The cause for this fracture mode and its effect on mechanical properties of the joints were investigated.
Effects of Heat Input on Mechanical Properties of AZ31 Mg Alloy Fabricated by FSP
Shou-fa LIU, Zhao-feng ZHOU, Chun-feng LI
2015, 35(1): 39-44. doi: 10.11868/j.issn.1005-5053.2015.1.007
[Abstract](283) [FullText HTML] (44) [PDF 1960KB](1)
Friction stir processing was conducted on AZ31 Mg alloy using common steel backing plate and copper backing plate with cool water channel as backboard respectively. The effects of thickness of workpiece, welding speed of FSP tool and cooling condition on mechanical properties of stir zone were investigated by means of OM, SEM, microhardness tester and tensile equipment. Results show that the recrystal grain size of stir zone decreases in turn from top layer to middle and bottom layers. The grain growth of samples could be restrained by decreasing the workpiece thickness and increasing welding speed of FSP tool and cooling rate. In the condition that the rotate speed and welding speed of FSP tool are 800r/min and 90mm/min, the grain in the bottom layer of the stir zone obtained is refined to 450nm. The microhardness of the stir zone reaches 96HV, which denotes an increase of 24HV compared with that using steel backing plate under the same FSP parameter. The yield strength, ultimate tensile strength and elongation are 1.27, 1.6 and 2.2 times over that of the as-received material.
Synthesis and Properties of 1-decene Oligomer Lubricant
Cheng-huan WANG, Yu-qi BI, Ming YANG, Ren-long JIANG, Ping YU, Chang-qiao ZHANG
2015, 35(1): 45-50. doi: 10.11868/j.issn.1005-5053.2015.1.008
[Abstract](443) [FullText HTML] (54) [PDF 2079KB](1)
Molecular dynamics simulation (MDS) of the interaction of 1-decne oligomer and the surface of steel at different temperature was conducted. The viscosity, viscosity index and pour point of 1-decne oligomer synthesized at different conditions were examined, and the catalyst was Et3NHCl -AlCl3 ionic liquid. Infrared spectrum (IR) and gas chromatography (GC) were used to characterize the 1-decne oligomer. Results show: the total surface energy change after the interaction of 1-decne trimer and the tetramer with the surface of the steel tends to be constant at a wide range of temperature; at condition of AlCl3/Et3NHCl=3(mole ratio), 5%wt catalyst in 1-decene,reaction temperature 100℃ and reaction time 7h, the viscosities of 1-decne oligomer at 40℃ and 100℃ are 57.49 mm2·s-1 and 9.94 mm2·s-1 respectively, the viscosity index is 60, and the pour point is -63℃; the 1-decne oligomer has very good properties of viscosity-temperature and low temperature fluidity. IR and GC show that the oligomerization is relatively thorough, and the product has a long linear side chain with regular structure; the total content of trimer and tetramer is 84.57%, which is consistent with the former work and the result of MDS.
Preparation Process Optimization of Heat Released 2PZ-PGMA Microcapsule-type Latent Curing Agent
Yu QI, Qiu-yu ZHANG, You-qiang SHI, Shan HE
2015, 35(1): 51-58. doi: 10.11868/j.issn.1005-5053.2015.1.009
[Abstract](164) [FullText HTML] (30) [PDF 3162KB](2)
A novel heat released microcapsule-type latent curing agent was successfully prepared by solvent evaporation technique with 2-phenylimidazole (2PZ) as core material and polyglycidy methacrylate (PGMA) as wall material. Systematic study of the effects of the kind of solvent and oil-water ratio, type and amount of surfactant, the core-shell feed ratio were carried out on the morphology of microcapsules, particle size and distribution, 2PZ content and yield, etc. When the solvent is methylene chloride, oil-water ratio is 4:5, surfactant is 0.4%(mass fraction) SDS and core-shell weight ratio is 1:1, the optimized preparation of the microcapsule curing agent is obtained.
Leakage Performances of Composite Laminate Structure Subjected to Low-velocity Impact
Qi CHEN, Zhi-dong GUAN, Wei HE, Zhao-jie JI, Cheng-zhi TIAN
2015, 35(1): 59-65. doi: 10.11868/j.issn.1005-5053.2015.1.010
[Abstract](205) [FullText HTML] (32) [PDF 3144KB](2)
The leakage performances of composite laminates subjected to low-velocity impact were investigated. Results indicate that a path is formed by matrix damage and delamination in the laminate, and the leakage would occur once the whole thickness of the laminate is penetrated by the path, while the leakage critical impact energy of the composite tank is between 23J to 25J. A finite element model was developed to simulate the damage in the laminate after impact, and judgments could be made based on the calculated result to determine whether the leakage happened. The calculated results are in good agreement with the test results. On the basis of the numerical model, the leakage performances of curved composite tanks were studied. Results of the investigation provide insight into the design method on composite tank structures.
Defect Characteristics and Ultrasonic Signal of Composite Repair Structure
Ting ZHANG, Kui LIU, Ting-ting WANG
2015, 35(1): 66-70. doi: 10.11868/j.issn.1005-5053.2015.1.011
[Abstract](198) [FullText HTML] (43) [PDF 2069KB](1)
This paper studies the defect characteristics of composite laminate structure repaired by vulcanizing machine. The results of the metallographic microscopic analysis indicate that the samples have no defects when the repair layers are two layers, while the porosity defects appear when the repair layers increase to 4. A large number of porosity defects appear in the repair layers as well as the film layer when the repair layers increase to 6, which result in weak bonding/debonding defects. The ultrasonic testing results are consistent with metallographic microscopic analysis, which reappear above defects very well.
Relationship between Ultrasonic Polarized Shear Wave and Internal Stress in Aluminum Alloy Bar
Cong JIN, Chao LU, Yi-wei SHI, Jing LIANG, Xiao WANG
2015, 35(1): 71-76. doi: 10.11868/j.issn.1005-5053.2015.1.012
[Abstract](181) [FullText HTML] (42) [PDF 1670KB](1)
The difference in velocities of ultrasonic shear waves at different angles between polarization direction and the direction of extrusion of aluminum alloy bar was first investigated by using a normal incidence polarized shear wave transducer, then the change of velocity of the ultrasonic shear wave polarizing at different angles with respect to the stress orientation under different applied stresses was studied. The experimental results indicate that there is a little difference of velocity of shear wave polarizing between parallel and perpendicular to the direction of extrusion in unstressed state, and anisotropy of the bar has little effect on the velocity of the polarized shear wave in different directions. When the specimen is submitted to an increasing axial loading, the time of flight of shear wave polarizing parallel to the direction of stress increases, the travelling time of shear wave polarizing perpendicular to the direction of stress decreases; after eliminating the influence of change of the propagation length of the ultrasonic wave brought by the elastic deformation of material, the results find that velocity of shear wave polarizing parallel to stress orientation decreases, velocity of shear wave polarizing perpendicular to stress orientation increases; the effect of stress which is parallel to polarization direction on velocity of the shear wave is more than that of stress which is normal to polarization direction on ultrasound velocity. This experiment provides a non-destructive method for the measurement of the plane stress field within material, which can non-destructively evaluate internal stress of material.
Analysis of Magnetic Particle Indication about 15-5PH Precipitation-hardening Stainless Steel
Shu-zhi WANG, Zi-liang GE, Xue-dong REN, Hai-yan QIAO
2015, 35(1): 77-81. doi: 10.11868/j.issn.1005-5053.2015.1.013
[Abstract](236) [FullText HTML] (43) [PDF 3056KB](2)
The strip,flaky and straight indication were detected when 15-5PH aeronautical precipitation-hardening martensitic stainless steel was tested by the magnetic particle testing method. The cause of different indication was discovered by their characteristics and microstructure. The technological process and the indication estimating method were established by analyzing magnetic parameters under different heat treatment condition in the cleanliness magnetic particle testing. The study finds that the indication is mainly caused by ferrite and asymmetric microstructure. The result has laid the foundation for the evaluation of magnetic particle indication and the formulation of the criteria in the magnetic particle testing process of precipitation-hardening martensitic stainless steel used in aviation manufacture engineering, and ensured the work of magnetic particle testing proceeds successfully.
Test Methods for Determining Flaw Tolerance Value of 7050 Aluminum Alloy Forging
Ben-run HU, Shao-jun MA, Di-hua TONG, Jian-zhong LIU, Ben-yin ZENG
2015, 35(1): 82-86. doi: 10.11868/j.issn.1005-5053.2015.1.014
[Abstract](215) [FullText HTML] (25) [PDF 1904KB](1)
Flaw tolerance design absorbs the characteristics of helicopter and is applied in the design of it. The methods to get the flaw tolerance value are not definite; thus, this paper presented its testing methods. The values of three defects were tested by fatigue limit method and computed by finite element method and Y. Murakami function. The results show that the flaw tolerance values of three defects are essentially the same and lower than that of the threshold of long crack. That means it is relatively dangerous to use the value of threshold of long crack. The flaw tolerance values calculated by the two methods are similar, and the values computed by Y. Murakami function are slightly lower than that by finite element method.
Silica Aerogel Materials: Preparation, Properties, and Applications in Low-Temperature Thermal Insulation
Zhi-hua ZHANG, Wen-qin WANG, Guo-qing ZU, Jun SHEN, Bin ZHOU, Ya LIAN
2015, 35(1): 87-96. doi: 10.11868/j.issn.1005-5053.2015.1.015
[Abstract](259) [FullText HTML] (44) [PDF 3746KB](1)
Owing to the unique nanoporous structure, SiO2 aerogels have many extraordinary properties that other materials cannot match, such as extremely high porosity, high specific surface area, extremely low thermal conductivity and low density. These extraordinary properties enable SiO2 aerogels to have great application potential in efficient thermal insulation and sound insulation, etc. In this review, the sol-gel preparation process and mechanism of silica aerogels are studied, and the thermal, mechanical, optical and hydrophobic properties of silica aerogels are overviewed. Meanwhile, the relationship between the microstructure and their properties are analyzed. Current application situation and potential of silica aerogels on low-temperature thermal insulations are introduced.

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