- Volume 45,Issue 3,2015 Table of Contents
>综述
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2015, 45(3).
Abstract:
In this paper, the oxidation behaviors of ZrB2 and its composites were reviewed. The results shownthat the ZrB2 ceramic is one of the promising high-temperature structure materials. The failure of ZrB2 ceramic wasdue to the volatile and failure of B2O3 protective layer. For the ZrB2 -SiC composite ceramic, its antioxidant propertywas improved at high temperatures by the addition of SiC. Also, the oxide structures of ZrB2 -SiC ceramic at differenttemperatures were described in detail. Based on these discussions, a new way for further improving oxidation resistanceand service temperature of ZrB2 -SiC ceramic was described and illustrated by addition of TaC and LaB6 to formternary composite ceramics. >计算材料学
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2015, 45(3).
Abstract:
On the basis of the theory of modulus, the mathematic function of the modulus with parameters ofpseudo-graphite crystallite for carbon fiber was derived. The results indicated that the crystalline modulus of carbonfiber was affected by the shape factor and the orientation angle. With the increasing of shape factor, the crystallinemodulus of carbon fiber was rised up firstly and then decreased. While the orientation angle was decreased, the moduluswas increased. The calculated modulus of carbon fiber from crystalline parameters, which was obtained from X-raydiffraction analysis, was closed to the measured value. It means the equation was satisfied the structure dependence ofthe modulus for carbon fiber -
2015, 45(3).
Abstract:
In order to accurately model the overlapping pyrolysis reactions of phenolic resin, thermal analysis experimentwith phenolic resin under five constant linear heating rates is conducted, and a Gaussian peak separationmethod is proposed. In this method, through the analysis of the differential thermogravimetric (DTG) curves of phenolicresin and the types and contents of the thermal decomposition products at different temperatures, the pyrolysisreactions of phenolic resin are divided into four. The results of peak separation are in good agreement with the experiments,which has important significance on the true determination of the kinetic parameters for the thermal decompositionof phenolic resin. -
2015, 45(3).
Abstract:
In order to get solder information of thermal fatigue state, shear force test method and nonlinear leastsquare method are used. A lead-free solder joint with 1210 chip resistor is the research object. A solder joint thermalfatigue life prediction method based on the solder joint shear strength test is put forward. The test of shear force-thermalfatigue life is done. According to 0, 300, 600, 900, 600, 1500 cycle data, Gauss-Newton of nonlinear leastsquare method is used to fit curves based on Matlab programming. By using the shear force value fell by 30% failurecriteria defined, the solder joint failure cycle number is 1439. 04. The method can be used to solder joint shearstrength of solder joint fatigue state monitoring, estimates, the same to the other kinds of solders. >新材料新工艺
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2015, 45(3).
Abstract:
SiBN fiber-reinforced nitride ceramic matrix composite materials were prepared by the precursor polymerinfiltration/ pyrolysis(PIP) technology, and the performances of SiBN fibers, polyborosilazane organic precursorsand SiBN fiber-reinforced ceramic matrix nitride composites were investigated. Experimental results indicated that lowcarbonceramics are prepared by SiBN precursor pyrolysis under ammonia atmosphere. Dielectric constant of pyrolysisproducts is about 3. 2, and the dielectric loss is less than 0. 01. The content of C and O elements in SiBN fiber arehigh, and the presence of carbon element had notable impact on the dielectric properties. The flexural strength andmodulus of prepared nitride ceramic matrix composites are 88. 52 MPa and 20. 03 GPa, respectively. -
2015, 45(3).
Abstract:
The micropores of the rayon based carbon fiber precursors were studied during the pyrolysis process.Results indicated that the longitudinal radius of the micropores increased gradually from 3. 88 nm to 7. 04 nm while theevolution trend of transversal radius was inverse which decreased to 3. 15 nm from 3. 86 nm, thus the shape of the mirocporesbecame needle. Meanwhile, the fractal dimension of transversal micropores increased from 2. 40 to 2. 61 andthe fractal dimension of longitudinal micropores fluctuated in the process from 2. 00 to 2. 23, which indicated theroughness of the micropores increased gradually. The micropore is a major factor in controlling the mechanical propertyof fibers, therefore it's important to study the micropores. -
2015, 45(3).
Abstract:
Isocyanate can be used as hardener of epoxy resin. The curing process was studied by comparing thedifferences of the final structures under different curing conditions. Altering the molar ratio of isocyanate to epoxidegroups, the changes of structure during curing and final properties of the cured materials were investigated by usingFTIR/ ATR,differential scanning calorimetry(DSC),dynamic thermal mechanical analysis(DMTA) and so on. As theresults indicated, the curing process of epoxy/ isocyanate formulations can be divided into three stages in order of increasingtemperature. Trimerization of isocyanate took place at first. And the following stages are a complex process:oxazolidonerings are prepared by Isocyanate and epoxy resin firstly. Trimerization of isocyanate took place among the oligomersterminated by isocyanate groups with oxazolidone rings as linear chain extenders. Oxazolidone rings were preparedby isocyanurates and remanent epoxy resin at the last stage. And the transition between oxazolidone rings andisocyanurate rings is a reversible process. Different structures ascribed to initial ratios lead to the different performances.When I/ E=1. 8, the isocyanate/ epoxy resin/ glass fiber formulation composition appeared a good comprehensivemechanical property. The bending strength,bending modulus and interlaminar shear strength of the isocyanate/ epoxyresin/ glass fiber formulation composition are 652. 53 MPa,3 3270. 63 MPa,31. 66 MPa,respectively,better thanthose MeHTPA/ epoxy resin/ glass fiber composites. When I/ E=2. 0,the Tg reached 305℃,higher than the temperatureof traditional epoxy resin curing formulations,obviously. -
2015, 45(3).
Abstract:
SiC coating modified Cf by CVD, then fabricated (SiC)Cf / Si3N4 composite by gelcasting. The effectof (SiC)Cf content toward the mechanical and absorbing properties of the composite were investigated. The flexurestrength of (SiC)Cf / Si3N4 composites reduced 112 MPa compare with Si3N4 ceramic and the fracture toughness increase11. 5 MPa·m1/2 when the (SiC)Cf content is 10wt%, meanwhile both the real (ε') and imaginary (ε″) permittivityof (SiC)Cf / Si3N4 composite ceramics reached maximum, the dielectric constant ε' is about 15 to 18 and ε″is about 6 to 8; the reflectivity of the composites moved to a lower frequency with the (SiC)Cf content and thicknessincreased. -
2015, 45(3).
Abstract:
Nano-TiO2 was dispersed uniformly in epoxy resin by the mixed process and epoxy/ nano-TiO2 resinwere manufactured by casting process. The NOL rings and Ф150 mm standard pressure vessels of T700 carbon fiber/ epoxyand T700 carbon fiber/ epoxy/ nano-TiO2 composites were manufactured by wet-winding. The nano-TiO2effect on theproperties of epoxy casting resins and T700 carbon fiber/ epoxy composites were also studied. The results show that theaddition of nano-TiO2is reinforced differently on epoxy resins and T700 carbon fiber/ epoxy composites. Comparing withthe epoxy without nano-TiO2, its tension strength and flexural strength of epoxy/ nano-TiO2 system are increased respectively9.2% and 9.8%. The interlaminar shear strength of T700 carbon fiber/ epoxy/ nano-TiO2 NOL rings reached 87． 7MPa, increasing 22.3%. The vessel performance factor of Ф150 mm pressure vessels are 43. 4 km, and the strengthtransfer rate of T700 carbon fiber is 94.3%. Comparing with the composites without nano-TiO2, its vessel performancefactor and strength transfer rate of T700 carbon fiber are increased respectively 9.9% and 3.3%. -
2015, 45(3).
Abstract:
According to characteristics of vacuum-assisted RTM process,processing parameter of the powder fillerintroduced resin-based composite materials were detered. The powder filler is dispersed in ethyl acetate solution,dispersantand binder were added to prepare a good dispersion of the powder filler suspension, and the quality of the powderfill and dispersant were detered to be 1 ∶0.5. Quantitative spraying the powder filler reinforcement fibers in order to modifythe composite,and analysis the effection of the powder filler is dispersed in the solution and bonded state of the reinforcingfibers. SEM observation reveal that the modified fibers,powder filler can relatively uniform adhesion in the fibersurface. Due to the powder filler adhesion in the fiber surface,breaking srength of failaments reduced about 10%. -
2015, 45(3).
Abstract:
According to disbond of damaged metallic structures bonded with composite patches, a three dimensionalfinite element analysis model was developed for the composite repairs, which conforms with the results of experiencedformula. The disbond model is also developed by the basic model, and equivalent distance was proposed foranalyzing the effects of disbond with different sizes and positions. The result shows that the large disbond is more effectivethan little one, there is a strength sensitive zone near the crack tip and it is determined by crack length. -
2015, 45(3).
Abstract:
The relationships between microstructures and mechanical properties of Ti-55531 titanium alloy wereinvestigated, by using statistic analysis on the microstructure characteristics, such as width of α platelet, β grain size,grain boundary α discontinuity and volume fraction of α phase. The results show that,with the increase of the temperatureof annealing, the average β grain size increases from 86 μm to 210 μm, grain boundary α discontinuity decreases,the volume fraction of needle-like α phase decreases first and then increases. The extension rate, statics toughnessand crack initiation energy decrease while the crack propagation energy increase with the growth of β grain size.Statics toughness is positive correlated with the grain boundary α discontinuity. There is a positive correlation betweenthe volume fraction of α phase and yield strength. -
2015, 45(3).
Abstract:The porous aluminum materials were prepared by using the spark plasma sintering. The results
showed that, after sintered at 350℃ by SPS, the porous aluminum materials with good structural stability and mechanical
properties, the pore size distribution and the porosity (54. 07%) could be prepared. Through analysis the
phase of material, we could find that the cleanliness of the materials is high and nothing will cause the pollution of
materials. -
2015, 45(3).
Abstract:NiCrAlY/ Al2O3 composite coatings were fabricated by micro-arc plasma spraying technology with internal
and external feedstock injection methods. The effect of powder infection method on the phase composition, microstructure
and dielectric properties was analyzed. Results show that: compared with the coatings prepared with external
feedstock injection method, the deposition efficiency of the coatings with internal feedstock method is higher and
the porosity of that is lower. Because of the completely melted α-Al2O3 particles, the coatings prepared with internal
feedstock injection method are mainly composed of γ/ γ′ and γ-Al2O3, and their microstructure is dense, the distribution
of NiCrAlY particles is uniform. The measurements of dielectric properties revealed that the real and imaginary
parts of the coatings with external feedstock injection method almost do not vary with frequency. However, the real
and imaginary parts of the coatings with internal feedstock injection method decrease with the increase of frequency,
which represents obviously frequency dispersion phenomenon. -
2015, 45(3).
Abstract:A three-dimensional finite element model is established to analyze and optimize the slope angle of
sandwich structure ramp transition region. Based on the finite element analysis software MSC,Patran/ Nastran the finite
element model of sandwich structure considering the decrease of panel layer of transient slope zone. After studying
the structural mechanical behavior formed in uniaxial compression load, the article further discussed the influence of
slope angle for the intensity and stability of regional structure of sandwich structure transition. The results show that
when the foam sandwich structure slope angle is between 25° to 30°,it can improve structure bearing capacity and reduce
the structure weight of dual purpose. >测试分析
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2015, 45(3).
Abstract:The principle and the applications of infrared thermography non-destructive testing (NDT) technology
are described in this paper. Experiment results show that, the infrared thermography NDT technology is an effective
method for several adhesive products quality testing, such as, glass-fiber-reinforced-foam bonding structure, cork
bonding structure, composite honeycomb sandwich structure. It is believed that infrared thermography NDT technology
has widely application potential in future. -
Mechanical Properties of Single-Lap Self-Pierce Riveted Jointsin Dissimilar Sheets of Titanium Alloy
2015, 45(3).
Abstract:In the paper, in order to study mechanical properties of single-lap self-pierce riveted joints in dissimilar
sheets of titanium alloy, the method of cross-section visual verification were applied to analyze the quality of four
joints. The quasi static mechanical properties test was used to test mechanical properties of copper alloy-titanium alloy
joints(H62-TA1 joints) and titanium alloy-aluminum alloy(TA1-AA5052 joints) , and the load-displacement curve
of the two joints was acquired from the test. The Dixon guideline was used to reject abnormal values, and the method
of coefficient of variation was used to verify the reliability of the test data. The results show that the H62-TA1 joint is
superior to the TA1-H62 joint, and the TA1-AA5052 joint is superior to the AA5052-TA1 joint. The strength of the
H62-TA1 joint (5 177. 8 N) is higher than the TA1-AA5052 joint (4 296. 9 N), and the energy absorption value of
the H62-TA1 joint (21. 9 J) is greater than the TA1-AA5052 joint (10. 2 J). The failure mode of the H62-TA1
joint is the rivet being pull out, and the failure mode of theTA1-AA5052 joint is the lower sheet being snapped. -
2015, 45(3).
Abstract:Several 2A12 aluminum alloy forging stocks were found to have fractured in the production process.
In this article, morphological observation and fraction analysis were employed to investigate the reason why cracking
phenomenon happened. In addition, the article studied comparatively the cracking forging stock with heat treatment,
the forging stock without heat treatment and the aluminum bar. The results indicated that the fracture mode of the forging
stock belong to brittle fracture, and the crack formed in the heat treatment process and related to the coarse-grain
generated in the treatment process due to the improper forging process. -
2015, 45(3).
Abstract:The mechanical properties and static failure mechanism of the titanium, aluminum lithium and aluminum
alloy self-piecing riveted joints were studied by the self-piecing riveting system, materials test machine and scanning
electron microscope. The results showed that the average maximum tensile shear load of the TA1 joints(6 285. 0
N) is the largest, the 8090 joints took the second place, the 5052 joints is the smallest. Different metal materials selfpiecing
riveted joints presented a great different static failure mode. The rivets in TA1 joints appeared a failure process
from intergranular fracture to ductile fracture. The 8090 joints appeared a failure process of the materials being rubbed
and cleavage fracture. The 5052 joints appeared a failure process of the materials only being rubbed.
