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The aqueous solution properties of an ampholytic poly[3-dimethyl (methacryloyloxyethyl) ammonium propane sulfonate] [poly(DMAPS)] are studied by measurements of cloud point determination, intrinsic viscosity, degree of binding, and ionic strength. The minimum salt concentration and intrinsic viscosity of this polyampholyte are related to the type and concentration of added salt. Both the polymeric and monomeric betaines in the presence of NaCl have the lower degree of binding, indicating that the proton ion (H+) is relatively difficult to bind the SO?3 at the end of sulfobetaine. An increase in ionic strength causes the pKa to decrease at the half-neutralization point. 相似文献
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Lee Geun Hee Rhee Chang Kyu Kim Whung Whoe Ivanov Victor V. 《Metals and Materials International》2003,9(4):379-382
Magnetic pulse compaction (MPC) allows one to maintain a nanostructured state in nano powder metallic compacts and to achieve
near theoretical density. In this study, nano Al powders of about 80 nm in diameter were prepared with the Pulse Wire Evaporation
(PWE) method and passivated with a thin Al2O3 layer on a surface about 2 nm thick to prevent further agglomeration and oxidation. The powders were compacted with the dynamic
compaction of magnetic pulsed force. The effects of the compaction temperature and passivated oxide layer of Al powders on
mechanical properties were investigated. The prepared compacts were considered as the composite materials of the metal-matrix
containing oxides of their own metal. A fine and uniform bulk structure was kept up to 400°C, which showed neither further
agglomeration nor grain growth during compaction and heat treatment due to the formation of Al/Al2O3 composites.
This article is based on a presentation made in the 2002 Korea-US symposium on the “Phase Transformations of Nano-Materials”,
organized as a special program of the 2002 Annual Meeting of the Korean Institute of Metals and Materials, held at Yonsei
University, Seoul, Korea on October 25–26, 2002. 相似文献
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Min Ku Lee Whung Whoe Kim Chang Kyu Rhee Won Jong Lee 《Metallurgical and Materials Transactions A》1999,30(4):961-968
Coating of TiN film was done by reactive magnetron sputter ion plating to improve the liquid impact erosion resistance of
steam turbine blade materials, 12Cr steel and Stellite 6B, for nuclear power plant application. TiN-coated blade materials
were initially deformed with depressions due to plastic deformation of the ductile substrate. The increase in the curvature
in the depressions induced stress concentration with increasing number of impacts, followed by circumferential fracture of
the TiN coating due to the circular propagation of cracks. The liquid impact erosion resistance of the blade materials was
greatly improved by TiN coating done with the optimum ion plating condition. Damage decreased with increasing TiN coating
thickness. According to the theoretical analysis of stresses generated by liquid impact, TiN coating alleviated the impact
stress of 12Cr steel and Stellite 6B due to stress attenuation and stress wave reactions such as reflection and transmission
at the coating-substrate interface. 相似文献
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Young Hwa Oh Chang Kyu Rhee Do Hyang Kim Geun Hee Lee Whung Whoe KIM 《Journal of Materials Science》2006,41(13):4191-4195
Formation of aluminum hydroxide by a hydrolytic reaction of nano aluminum powder synthesized by a pulsed wire evaporation
(PWE) method has been studied. The type and morphology of the hydroxides were investigated with various initial pH and temperatures.
The nano fibrous boehmite (AlOOH) was formed predominantly over 40°C of the hydrolytic temperature, while the bayerite (Al(OH)3) was formed predominantly below 30°C with a faceted crystalline structure. As a result, the boehmite showed a much larger
specific surface area (SSA) than that of bayerite. The highest SSA of the boehmite was found about 409 m2/g. 相似文献
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Lee Chung Ro Lee Hoong Woo Song Jae Sung Kim Whung Whoe Park Sung 《Journal of Materials Synthesis and Processing》2001,9(5):281-286
Nanometer-sized ZnO powders for photocatalytic applications were prepared by a solution combustion method with various starting materials and fuels. It was easy to obtain single-phase ZnO powders using the solution combustion method regardless of the starting materials and fuels. However, the particle size and shape of the synthesized ZnO powders were different than the used fuel. Using glycine as a fuel, the particle shape of ZnO powders was spherical with uniform nanosize. On the other hand, using carbohydrazide as a fuel, the particle shape was platelike. The ZnO powder synthesized using Zn(OH)2 and glycine as starting material and fuel, respectively, showed good powder characteristics, such as average grain size of 75 nm and the specific surface area of 94 m2/g. The average particle size and specific surface area were greatly dependent on the types of oxidants and fuels. Removal of silver ions from a used photo-film developing solution was attempted to examine the photocatalytic activity of the prepared ZnO powders. It also showed excellent photocatalytic properties in that the silver ions were completely removed from the solution within 3 min. 相似文献
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