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821.
The coarsening theory of a spherical particle in a ternary alloy developed by Kuehmann and Voorhees (KV) has been generalized to any centro-symmetric particle. A classical thermodynamic analysis reveals that the generalized KV theory enables us to estimate the interface energy of a particle with a fixed shape, even if the shape of the particle is not controlled by minimization of the interface energy. Data on the coarsening of spherical, {0 0 1}-faceted cuboidal and {1 1 1}-faceted octahedral precipitates in a Cu–Co alloy, a Cu–Fe alloy, and three Cu–Co–Fe alloys with different Co and Fe contents during aging at 873–973 K have been collected by transmission electron microscopy and electrical resistivity. By applying the generalized KV theory to the experimental data, the energies of sphere, {0 0 1} and {1 1 1} interfaces have been determined. Their energies increase with increasing the Fe composition in the alloys. 相似文献
822.
Takayuki Nagano Naoki Uno Tomohiro Saitoh Satoshi Yamazaki Yuji Iwamoto 《Chemical Engineering Communications》2007,194(2):158-169
Mesoporous anodic oxidized alumina (MAOA) capillary tubes with and without a barrier layer have been synthesized by applying a pulse-sequential voltage. The single gas permeances at an elevated temperature and the thermal and hydrothermal stabilities of MAOA were investigated. A highly oriented radial mesopore channel with pore sizes from 40 to 4 nm was formed in the MAOA tubes. Micropores with sizes from 0.4 to 0.8 nm were formed in the barrier layer. The H2 permeance of MAOA with a barrier layer (barrier type) was approximately 540 times lower than that of MAOA without a barrier layer (block type) at 773 K. The H2/N2 permselectivity of the barrier type in the temperature range from 333 to 673 K was 3.4; those of the barrier type at 773 and 823 K were 4.4 and 11, respectively. On the other hand, the H2/N2 permselectivities of the block type were from 3.1 to 3.6 in the temperature range from 333 to 773 K. The H2 permeance and the H2/N2 permselectivity of the amorphous silica membrane on the block type were 1.1 × 10-7 mol/m2 · s · Pa and 40 at 773 K, respectively. MAOA synthesized by the pulse-sequential voltage method can be applied to the mesoporous support of the gas separation membrane at elevated temperatures. 相似文献
823.
Shinji Iwamoto Ryosuke Takahashi Masashi Inoue 《Applied catalysis. B, Environmental》2007,70(1-4):146-150
The direct decomposition of nitric oxide (NO) over barium catalysts supported on various metal oxides was examined in the absence and presence of O2. Among the Ba catalysts supported on single-component metal oxides, Ba/Co3O4 and Ba/CeO2 showed high NO decomposition activities, while Ba/Al2O3, Ba/SiO2, and Ba/TiO2 exhibited quite low activities. The effect of an addition of second components to Co and Ce oxides was further examined, and it was found that the activities were significantly enhanced using Ce–Mn mixed oxides as support materials. XRD results indicated the formation of CeO2–MnOx solid solutions with the cubic fluorite structure. O2-TPD of the CeO2–MnOx solid solutions showed a large desorption peak in a range of relatively low temperature. The BET surface areas of the CeO2–MnOx solid solutions were larger than those of pure CeO2 and Mn2O3. These effects caused by the addition of Mn are responsible for the enhanced activities of the Ba catalysts supported on Ce–Mn mixed oxides. 相似文献