Authors: Yong Yee Kim, Young Min Park, Hoy Yul Park, Hong Chae Park, Seog Young Yoon
Abstract: Monodispersed Cu powders were prepared in aqueous solution through a wet-reduction
process with hydrazine hydrate (N2H4·H2O). In particular, the effect of the dispersant such as sodium
pyrophosphate decahydrate (Na4O7P2·10H2O), carboxymethyl cellulose sodium salt (CMC) in water
solvent on the particle size for the prepared Cu powders was investigated. The Cu powders essentially
were monodispersed and irregular in shape regardless of reaction temperature and dispersant. In the case
of adding the Na4O7P2·10H2O, the particle size of Cu powders increased with the increase of reaction
temperature, which the particles were agglomerated in irregular shape and became to be large. The
particle size distributions was asymmetry and to be broad regardless of reaction temperature. On the other
hand, when the CMC was added, the particle size of Cu powders, which were much finer compared with
adding the Na4O7P2·10H2O as a dispersant, was not much changed with reaction temperature. The particle
size distribution of Cu powder was much narrow regardless of reaction temperature. As a result, it would
be suggested that the CMC was more effective dispersant reagent to produce the monodispersed and fine
Cu powders with narrow size distribution using the wet chemical reduction process
2118
Authors: Hoang Tri Hai, Dong Jin Kim, Y.D. Kim, Chong Oh Kim, Hun Saeng Chung, Jong Gwan Ahn
Abstract: Ultrafine dispersed copper powders were prepared from copper (I) oxide (Cu2O) slurry
by a wet chemical reduction with hydrazine as a reductant. Palladium chloride (PdCl2) was used as
a nucleator along with its polymer stabilizer, polyvinylpyrrolidone (PVP). Sodium pyrophosphate
(Na4O7P2) was added as a surfactant. It was found that the use of Cu2O and Na4O7P2 exhibit very
strong impact on dispersity of the prepared Cu powders. In this study, we indicate the critical
conditions at which the particles aggregation still occurs even though the powders produced at high
zeta potential resulted from an appropriate addition of Na4O7P2.
741
Authors: Xiao Pan Che, Shi Zhen Zhu, Li Juan Yang, Qiang Xu
Abstract: Ultra-fine ZrB2 powders and ZrB2-SiC composite powders were synthesized by solution-based method, using zirconium oxynitrate (ZrO(NO3)2•2H2O), boric acid (H3BO3), phenolic resin, and tetraethyl orthosilicate (TEOS) as raw materials, respectively. The zirconia sol with other precursor was formed via adjustment of the pH value. After drying, grinding and sieving, the precursor powders were obtained. Exposed to carbothermal reduction heat treatments (1300°C~1500°C, 0.5h, flowing argon), pure ZrB2 powders and ZrB2-SiC composite powders with fine particle size (~1μm) were synthesized.
213
Authors: Yang Feng Huang, Ye Bin Cai, Hao Liu
Abstract: In this work, synthesis of the nanocrystalline Ce0.8Nd0.2O1.9 Solid solution Powders by a nitrate-glycine gel-combustion process was investigated. The effects of glycine/metal ratio and calcination temperature on the powders phase structure, morphology and particle were investigated. TG-DSC curves and XRD peak of different glycine/metal ratio show that smaller particle size can be obtained with a slightly fuel-deficient ratio. XRD results indicate that the as-prepared powders are crystallinzed in a single fluorrite structure. The crystalline size ranges from 9 nm to 24 nm, which increases with the increase of calcination temperature. The SEM results imply some organic agent may be eliminated by high temperature calcination process.
860
Authors: Jian Feng Tong, Ling Wang, Da Ming Chen
Abstract: A new technology, gel solid-state reaction, for synthesis of SrTiO3 ceramic composite powders is described in the present paper. This process, valuable for a great number of composite powders, is of great simplicity and has a relative low synthetic temperature of powders. The calcined lumped powder is porous and easy to grind. XRD and d-spacing-component figures of the solid solution powder demonstrated that the compounds were mutually miscible in the solid solutions, and SEM showed that they were uniform and substantially spherical with an average size of 1.0 μm in diameter. The remarkable advantages of the method are high yields, solvent-free, and environmental benign.
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