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61.
The mechanical properties and post-thermal aging properties of natural rubber (NR) and polybutadiene rubber (BR) blends at
different blending ratios are investigated herein. The experimental results show that both tensile and tear strengths of NR/BR
blends increase with increasing NR content. BR has a higher compression stiffness than NR. The deformation of BR is less than
that of NR under the same load conditions. With regard to aging properties, both tensile stress and strain of NR/BR blends
decrease after prolonged aging. In addition, the stress loss of BR is lower than that of NR, meaning that the aging resistance
property of BR is superior to that of NR. Furthermore, accumulated thermal history has shifted the glass transition temperature
(T
g) of NR/BR blends toward lower temperatures while the loss tangent (tan δ) value increases with prolonged thermal aging. 相似文献
62.
63.
1 INTRODUCTIONCoatingglassfiberwithleadproducesakindofnewcontinuouscomposite ,whichcanfindwideap plicationsinmanydifferentfields ,especiallyinthebatteryoftheEVsandHEVsthathasalreadybecomethemostimportantgoalinmostcountries[13] .Withakindofspecialtechnologythiskindofnewcompos itewirecanbeusedtoproducegridsofnewleadacidbatterythatisveryusefultotheEVsandHEVs .Thiskindofnewleadacidbatteryhasmanyadvan tages ,suchashigherspecificenergy ,lessinnerresis tance ,morequicklychargingcapabilityand… 相似文献
64.
Utilizing the existing properties of steel, a modern technological society has been constructed. While there are over 25,000
worldwide equivalent steels based on manipulating the eutectoid transformation, there exist only a handful of commercial nanostructured
steel alloys based on manipulating the more complex glass devitrification transformation. Thus, research on nanostructured
steels is in its infancy, and many further developments are expected with the demonstrated promise of developing new combinations
of superior properties. In this article, seven enabling metallurgical factors are presented that ultimately allow a variety
of nanostructured steel products to be produced in an ever-increasing array of industrial processing techniques. Additionally,
a case example of the formation of nanostructured steel are given showing how these factors can be harnessed on an industrial
scale. 相似文献
65.
66.
67.
The Sn−Ti−Zn ternary phase diagram has been constructed using the CALPHAD technique. The Ti−Zn binary system phase boundaries
were determined using differential scanning calorimetry and the solid-liquid diffusion couples method. In addition, the formation
energy of some stoichiometric compounds was obtained using first-principle band energy calculations. For the ternary system,
some alloys were prepared by equilibration at 600 or 700 °C, and the compositions of the precipitates were analyzed using
electron probe microanalysis. Thermodynamic assessment of the Ti−Zn and Sn−Ti−Zn systems was performed based on the experimental
information and by adopting reported values of the thermodynamic properties of the Sn−Zn and Sn−Ti binary systems. Microstructural
observation showed that Sn3Ti5Zn12 exists in the ternary system. Seven types of invariant reaction on the Sn-rich liquidus surface of the ternary system are
predicted by the phase diagram calculations. The ternary eutectic point falls at 0,0009 mass% Ti and 8.69 mass% Zn, at T=192.40°C, which is slightly lower than the calculated eutectic point of Sn−Zn binary alloy (T=192.41°C). Based on these results, a nonequilibrium solidification process using the Scheil model was simulated.
This paper was presented at the International Symposium on User Aspects of Phase Diagrams, Materials Solutions Conference
and Exposition, Columbus, Ohio, 18–20 October, 2004. 相似文献
68.
Understanding the Influence of Copper Nanoparticles on Thermal Characteristics and Microstructural Development of a Tin-Silver Solder 总被引:1,自引:0,他引:1
D.C. Lin T.S. Srivatsan G-X. Wang R. Kovacevic 《Journal of Materials Engineering and Performance》2007,16(5):647-654
This paper presents and discusses issues relevant to solidification of a chosen lead-free solder, the eutectic Sn-3.5%Ag,
and its composite counterparts. Direct temperature recordings for the no-clean solder paste during the simulated reflow process
revealed a significant amount of undercooling to occur prior to the initiation of solidification of the eutectic Sn-3.5%Ag
solder, which is 6.5 °C, and for the composite counterparts, it is dependent on the percentage of copper nanopowder. Temperature
recordings revealed the same temperature level of 221 °C for both melting (from solid to liquid) and final solidification
(after recalescence) of the Sn-3.5%Ag solder. Addition of copper nanoparticles was observed to have no appreciable influence
on melting temperature of the composite solder. However, it does influence solidification of the composite solder. The addition
of 0.5 wt.% copper nanoparticles lowered the solidification temperature to 219.5 °C, while addition of 1.0 wt.% copper nanoparticles
lowered the solidification temperature to 217.5 °C, which is close to the melting point of the ternary eutectic Sn-Ag-Cu solder
alloy, Sn-3.7Ag-0.9Cu. This indicates the copper nanoparticles are completely dissolved in the eutectic Sn-3.5%Ag solder and
precipitate as the Cu6Sn5, which reinforces the eutectic solder. Optical microscopy observations revealed the addition of 1.0 wt.% of copper nanoparticles
to the Sn-3.5%Ag solder results in the formation and presence of the intermetallic compound Cu6Sn5. These particles are polygonal in morphology and dispersed randomly through the solder matrix. Addition of microsized copper
particles cannot completely dissolve in the eutectic solder and projects a sunflower morphology with the solid copper particle
surrounded by the Cu6Sn5 intermetallic compound coupled with residual porosity present in the solder sample. Microhardness measurements revealed the
addition of copper nanopowder to the eutectic Sn-3.5%Ag solder resulted in higher hardness. 相似文献
69.
70.
各向异性Sm2Fe17Nx磁粉的结构与磁性能 总被引:11,自引:1,他引:11
研究了Sm2Fe12Nx磁粉的制备、结构与磁性能,发现Sm—Fe合金的铸态组织主要由Sm2Fe17、α—Fe和SmFe2三种物相组成,而经过1000℃均匀化退火48h处理后富Sm的SmFe2相基本消失,α—Fe相的品粒变小,数量减少。随着氯化时间延长到10h,Sm2Fe17相始终未改变其Th2Zn17型结构,而氯原子浓度增加,所有的X射线衍射峰均向小角度方向移动;但在氮化时间超过10h后,物相要发生变化,导致磁性能降低。在500℃下流动的氮气氛中对Sm2Fe17合金氮化2、4、6、10h未加磁场取向的磁粉中,以氮化6h的磁性能值最高:σr=35.44Am^2/kg(emu/g),Hc=58kA/m(729.03Oe)。磁性能值偏低的原因与测量磁场较低,粒径分布不均匀及粒径较大有关。 相似文献