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31.
PC/PET共混物的非等温结晶动力学 总被引:9,自引:0,他引:9
采用等速变温DSC法对PC/PET共混体系的非等温结晶动力学进行了研究,结果表明,从玻璃态结晶时,随着PC含量的增加,PET组分的结晶速率先增加后降低。耐从熔体结晶时,体系的结晶速率随着PC含量的增加而增加,讨论了PC对PET组分结晶过程的影响。 相似文献
32.
Cheol-Min Park Byung-Hyuk Min Jae-Hong Jun Juhn-Suk Yoo Min-Koo Han 《Electron Device Letters, IEEE》1997,18(1):16-18
We have fabricated a self-aligned offset-gated poly-Si thin film transistor (TFT) by employing a novel photoresist reflow process. The gate structure of the new device is consisted of two unique patterns: A main-gate and a sub-gate. The new fabrication method extends the gate-oxide over the offset region. With the assistance of the sub-gate and reflowed photoresist a self-aligned offset region is successfully obtained due to the offset oxide acting as an implantation mask. The poly-Si TFT with symmetrical offsets is easily fabricated and the new method does not require any additional offset mask step. Compared with the misaligned offset gated poly-Si TFTs, excellent symmetric electrical characteristics are obtained 相似文献
33.
Motoharu Fujigaki In Hong Yang Yoshiharu Morimoto Eung Kyo Han 《NDT & E International》1996,29(4):197-203
There is no good method to measure the shape and the strain distributions of a structure changing with time. We have previously proposed the Fourier transform grid method (FTGM) to measure the three-dimensional shape and surface strain distributions of stationary objects by analysing the two-dimensional grating images recorded with two cameras. In the stereoscopic method, it is very important to determine the accurate geometric parameters of the camera system. In this paper, the positions and the directions of cameras are accurately determined using the FTGM applied to images of a reference object on which a two-dimensional grating is drawn. Applications for analysing shape and strain distributions of vibrating rubber plates and a moving human skin are shown. 相似文献
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37.
Zhihui Zhang Bing Q. Han Kyung H. Chung Enrique J. Lavernia 《Metallurgical and Materials Transactions A》2006,37(7):2265-2273
The current study aims to provide fundamental insight into the behavior of microstructures containing grain sizes that span
multiple length scales. A commercial 5083 Al alloy was selected as the material of interest to facilitate comparison with
recently published data. The materials studied here were prepared via the thermal consolidation of powders that were cryomilled
for different times (i.e., 0, 2, 4, and 8 hours). Following consolidation, the resultant microstructure was characterized by an equiaxed grain morphology
with a size distribution centered around 200∼300 nm. Dispersed among the 200- to 300-nm grains were coarse-grained regions
or ligaments with a grain size ranging from 600 nm to 2 μm. The occurrence of coarse-grained regions is rationalized on the
basis of recrystallization or subgrain coarsening, whereas the occurrence of equiaxed fine regions is proposed to be a result
of continuous grain growth. Two types of microstructures were selected for study, containing coarse-grained volumes of approximately
28 pct and 43 pct that corresponded to an ultimate tensile strength (UTS) of 566 MPa and 535 MPa, and a fracture strain of
3.2 pct and 3.5 pct, respectively. The observed ductility and the relevant toughening mechanisms were discussed in light of
the presence of multiple length scales. 相似文献
38.
Bing Q. Han Farghalli A. Mohamed Enrique J. Lavernia 《Metallurgical and Materials Transactions A》2003,34(1):71-83
In the present study, the mechanical properties of Fe processed via severe plastic deformation (equal-channel angular pressing (ECAP)) at room temperature were investigated for the first time.
The grain size of annealed Fe, with an initial grain size of about 200 μm, was reduced drastically during ECAP. After eight passes, the grain size reaches 200 to 400 nm, as documented by means of
transmission electron microscopy (TEM). The value of microhardness during pressing increases 3 times over that of the starting
material after the first pass and increases slightly during subsequent pressing for higher-purity Fe. Examination of the value
of microhardness after eight passes as a function of post-ECAP annealing temperature shows a transition from recovery to recrystallization,
an observation that resembles the behavior reported for heavily deformed metals and alloys. The tensile and compression behaviors
were examined. In tension, a drop in the engineering stress-engineering strain curve beyond maximum load was observed both
in the annealed Fe and the ECAP Fe. This drop is related to the neck deformation. The fracture surface, examined by scanning
electron microscopy (SEM), shows vein patterns, which is different from the dimples found on the fracture surface of annealed
Fe. In compression, an initial strain-hardening region followed by a no-strain-hardening region was observed in the ECAP Fe.
The yield strength in tension of the ECAP Fe was observed to be higher than that in compression. The strengthening mechanisms
and softening behavior are discussed. 相似文献
39.
H. Tsukamoto T.D. Boone J. Han J.M. Woodall 《Photonics Technology Letters, IEEE》2005,17(7):1411-1413
We present a novel optical switching technique utilizing emission packet positioning of semiconductor heterostructure. A modulation-doped p-AlGaAs-GaAs heterostructure is employed to control spontaneous emission packet positioning with electric fields. Emission packets generated by optical input signals are brought over 150 /spl mu/m with electric fields, so the output fibers can detect the emission intensity as signals. The first-order analysis indicates that the drift velocity of minority electrons in GaAs limits the detectable maximum data rate and nanoseconds timescale signal routing operation at 20 Gb/s is possible at an electron drift velocity of 2/spl times/10/sup 7/ cm/s. 相似文献
40.
采用SE 3 0为固定液进行色谱柱分离 ,用外标定量法测定泥土中的微量六氯环戊二烯 ,结果最小检知量为 0 .18× 10 - 6 ,相关系数为 0 .99992。 相似文献