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91.
Sang-Gon Kim Jong-Sung Park Jae-Sul An Kug Sun Hong Hyunho Shin Hyungsun Kim 《Journal of the American Ceramic Society》2006,89(3):902-907
Various types of crystalline ceramic fillers (TiO2 , ZrO2 , Al2 O3 , MgO, and cordierite) were added to BaO–ZnO–B2 O3 –SiO2 (BZBS) glass (5–20 wt%), and the resultant dielectric constant, coefficient of thermal expansion (CTE), and optical reflectance were investigated for the application of the composites to the barrier ribs in plasma display panels. All the investigated fillers were partially dissolved into the glass at the fabrication temperature (575°C), and the residual fillers were aligned along the boundaries of sintered glass frits. By considering all aspects of the properties, the addition of TiO2 fillers of about 10 wt% to BZBS glass was the most desirable of the types of fillers investigated. The addition of TiO2 filler (10 wt%) yielded 61% in optical reflectance, 8.3 × 10−6 K–1 in coefficient of thermal expansion, and 15.5 in dielectric constant, which were properties comparable with the currently used Pb-based barrier ribs. 相似文献
92.
Kwang Ho Kim Soo Won Lee Dong Won Shin Chan Gyung Park 《Journal of the American Ceramic Society》1994,77(4):915-921
Antimony-doped tin oxide films were prepared on Corning glass substrate by chemical vapor deposition from a gas mixture of SnCl4 –SbCl5 –H2 O. The electrical conductivity and optical transmission of tin oxide films were studied with antimony doping. The film conductivity increased largely without losing optical transparency with a small addition of antimony. The increase of the conductivity was attributed mainly to more electrons donated by pentavalent Sb ions in the SnO2 lattice. Large additions of antimony, however, diminished the conductivity, optical transparency, and crystallinity of the film. The diminution was found to be caused by fine Sb2 O5 phases codeposited with SnO2 . 相似文献
93.
Soo‐kyung Shin Myung‐jin Jun Hyungki Hong 《Journal of the Society for Information Display》2014,22(2):122-128
In stereoscopic images, the crossing point of the viewing directions of the two eyes determines the perceived depth. Assuming that accommodation is affected by the positions of the crossing point, the effect of crossing point on minimum angle of resolution (MAR) was investigated. For 40 participants, MAR was measured by two‐alternative forced choice where Snellen optotype E of up and down directions were used as two kinds of stimuli. As the crossing point of the viewing direction of the left and right eyes moves farther from the sample display, the ability to identify the direction of letter E decreases at the optotype of the same line thickness. The change of MAR shows linear trends with respect to the optical power change that are the reciprocal of the distance from the participant to the crossing points located out of screen and on screen. 相似文献
94.
The interfacial reaction between styrene/maleic anhydride copolymer (SMA) and amine-terminated butadiene-acrylonitrile copolymer (ATBA) was observed using Fourier transform infrared (FTIR) imaging spectroscopy. The anhydride and amine reacted to form an imide. Each component was detected using a characteristic wavenumber, which was 1601 cm -1 for SMA, 2237 cm -1 for ATBA, and 1701 cm -1 for the imide. FTIR images were taken as the reaction proceeded at 150, 160, 170, and 180°C. At low temperatures (150 and 160°C), diffusion-controlled kinetics were observed since interdiffusion between the reactants did not appear in the images. On the other hand, both the diffusion front and the reaction front are observed in the images at high reaction temperatures (170 and 180°C), which indicates that the kinetics became reaction-controlled rather than diffusion-controlled. Absorbance profiles were extracted from the images and used for the calculation of the extent of reaction. The data were analyzed using the Frederickson and Milner theory based on the assumption of diffusion-controlled kinetics, and this theory fit the low reaction temperature data. 相似文献
95.
Continuous solution copolymerization of methyl methacrylate with ethyl methacrylate or n-butyl methacrylate was carried out
in a continuous stirred tank reactor. Solvent and initiator used were toluene and benzoyl peroxide, respectively. Reaction
volume was 1.2 litters, residence time 3 hours and polymerization temperature 80°C. The copolymerization conversions were
analyzed by UV spectrophotometry and confirmed by measuring the solid weights of copolymers obtained after evaporating solvent.
The copolymerization of methyl methacrylate and alkyl methacrylates followed the second order kinetics. The simulated conversions
and copolymerization rates were compared with the experimental results. The average time to reach dynamic steady-state was
three and half times of the residence time. 相似文献
96.
The irreversible deformation mechanisms of poly(vinyl chloride) with a semicircular notch under slow tensile loading have been studied as a function of sheet thickness. Initially, core yielding was observed in the optical microscope as two families of slip lines growing from the notch surface in the centre of the specimen. The size and shape of the core yielding zone could be described by plasticity analysis. A stress-whitened zone subsequently initiated near the tip of the slip line zone. The stress whitening was caused by 1 m voids that were visible in the scanning electron microscope. The mean stress for stress whitening was calculated to be 43.0±1.5 MPa by a plastic stress analysis of a pressure-dependent yield material. By assuming a constant mean stress along the boundary of the stress-whitened zone, the one-dimensional shift of the elastic stress distribution was obtained. At higher stresses, hinge shear and intersecting shear were observed for thick and thin sheet, respectively. 相似文献
97.
Dong-il Shin François Gitzhofer Christian Moreau 《Journal of Thermal Spray Technology》2007,16(1):118-127
Metal-based thermal barrier coatings (MBTBCs) have been produced using high frequency induction plasma spraying (IPS) of iron-based
nanostructured alloy powders. The study of MBTBCs has been initiated to challenge issues associated with current TBC materials
such as difficult prediction of their “in-service” lifetime. Reliability of TBCs is an important aspect besides the economical
consideration. Therefore, the study of MBTBCs, which should posses higher toughness than the current TBC materials, has been
initiated to challenge the mechanical problems of ceramic-based TBCs (CBTBCs) to create a new generation of TBCs. The thermal
diffusivity (TD) (α) properties of the MBTBCs were measured using a laser flash method, and density (ρ) and specific heat
(C
p) of the MBTBCs were also measured for their thermal conductivity (k) calculation (k = αρ
C
p). 相似文献
98.
A study has been made to investigate the superplastic deformation mechanisms of 7475 Al alloy in relation to the variation of grain size ranging between 5.5 μm and 13 μm. The strain-rate sensitivity (m) was increased with decreasing grain size in the superplastic deformation regime. Microstructural investigation after tension tests revealed that the dispersoid free zones were produced mostly at the grain boundaries normal to the tensile direction. A new model for describing the deformation behavior of the 7475 Al alloy has been proposed based on the assumption that the grain boundary sliding was accommodated by both diffusional flow and slip. This new model well predicts many aspects of experimental results. 相似文献
99.
Kyung-Man Moon Hwang-Rae Cho Myung-Hoon Lee Sung-Kyu Shin Sung-Cheol Koh 《Metals and Materials International》2007,13(3):211-216
The differences between the general corrosion and microbiologically influenced corrosion (MIC) of steels were investigated
in terms of its electrochemical behavior and surface phenomena. The corrosion potential of steels in the absence of SRB (sulfate-reducing
bacteria) shifted to a negative value with the immersion time. However, the potential of the presence of SRB shifted to a
positive value after 30 days' incubation, indicating the growth of SRB biofilms on the test metal specimens and the formation
of corrosion products. In addition, the color of a medium inoculated with SRB changed from gray to black. The change in color
appeared to be caused by the formation of pyrites (FeS) as a corrosion product, while no significant change in color was observed
in a medium without SRB inoculation. Moreover, corrosion rates of various steels tested for MIC were higher compared to those
of steels in the absence of SRB. In particular, the corrosion current density of TMCP steels in the presence of SRB was larger
than that of other steels. Pitting corrosion was also observed at the surface of all steels in the SRB-inoculated medium.
The pitting corrosion likely occurred due to SRB that was associated with the increasing corrosion rates through increasing
cathodic reactions, which caused a reduction of sulfate to sulfide as well as the formation of an oxygen concentration cell. 相似文献
100.
Laser-assisted machining of compacted graphite iron 总被引:2,自引:0,他引:2
Compacted graphite iron (CGI) is a material currently under study for the new generation of engines, including blocks, cylinder liners, and cylinder heads. Its unique graphite structure yields desirable high strength, but makes it difficult to machine, thus resulting in a machining cost. Laser-assisted machining (LAM) is adopted to improve its machinability and hence machining economics. The machinability of CGI is studied by varying depth of cut, feed, and material removal temperature and then evaluating resultant cutting forces, specific cutting energy, surface roughness, and tool wear. At a material removal temperature of 400 °C and a feed of 0.150 mm/rev at a cutting speed of 1.7 m/s, it is shown that tool life is 60% greater than conventional conditions at a feed of 0.100 mm/rev. Surface roughness is improved 5% as compared to conventional machining at a feed of 0.150 mm/rev. CGI microstructure evaluated post machining by sectioning and polishing shows no change. An economic analysis shows that LAM can offer an approximately 20% cost savings for the machining of an engine cylinder liner. 相似文献