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Dong-Wook Park Dae-Hwan Kim Hye-Seong Kim Youg-Sam Kwon Kwon-Koo Cho Su-Gun Lim In-Shup Ahn 《Research on Chemical Intermediates》2014,40(7):2415-2421
Tool steels have a large range of applications including hot and cold working of metals and injection molding of plastic or light alloys. High-speed steel (HSS) is specifically used for cutting tools and for components subjected to extreme wear conditions, because of its high strength, wear resistance, hardness, toughness, and fatigue resistance. The microstructure of HSS can be described as a metallic matrix iron composite containing a dispersion of hard and wear-resistant carbides. Specimens were manufactured experimentally from T42 powder (50–80 vol%) and mixed binder (20–50 vol%) by powder injection molding. The binders (green parts) were debound in n-hexane solution at 60 °C for 8 h and thermally debound in a mixed N2–H2 gas atmosphere for 8 h. Specimens were sintered under high vacuum (10?5 Torr) at different temperatures. When sintering was performed at 1,260 °C, the specimen sintered under high vacuum had the highest hardness (550 Hv). The carbides were smaller (1 μm) and well distributed. Grain size was 10 μm. When sintering was performed under high vacuum at temperatures above 1,280 °C the carbides changed to eutectic carbide located at grain boundaries. Grain growth was observed. Specimens sintered at other pressures had lower density and hardness than those sintered under high vacuum. 相似文献
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Bak Yu-Rim Kim Gyeong-Ok Hwang Moon-Jin Cho Kwon-Koo Kim Ki-Won Ryu Kwang-Sun 《Journal of Sol-Gel Science and Technology》2011,58(2):518-523
The incorporation of nano-crystalline semiconductors with novel kinds of ordered microstructure is a very important area of
research in the field of dye sensitized solar cells. A sol–gel method involving hydrolysis of titanium isopropoxide was used
to form TiO2 nanoparticles on the surface of SiO2 spheres. In this process, 1, 5, or 10 wt% of SnCl2.2H2O was added to the sol–gel solution. To prepare TiO2/SnO2 nanoparticles with a half hollow sphere structure, SiO2 was removed with NaOH solution. The crystal phase, crystal shape, and surface properties of the metal oxide nanocrystals
were studied by x-ray diffraction and scanning electron microscopy. The photovoltaic performance of the TiO2/SnO2 nanoparticles with half hollow sphere structures was measured. The dye sensitized solar cell using nanoporous TiO2 as electrode materials exhibits an overall conversion efficiency of 7.36% with a light intensity of 100 mW/cm2. The short circuit photocurrent (Isc), open circuit photovoltage (Voc), and conversion efficiency (η) of these solar cells were improved over conventional materials. 相似文献
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