Phototrogy of Alkaline Earth Tungstates Doped with Bismuth

Calcium, strontium, and barium tungstates and their solid solutions, doped with a small amount of bismuth, color remarkably on exposure to ultraviolet light and return to the original white by thermal fading or optical bleaching. The factors affecting the darkening and fading processes were studied experimentally. Under the same irradiation conditions the intensity of uv-induced coloration depended on the Bi content and preparation temperature of the tungstates. Bi contents higher than 0.1 molyo and preparation temperatures higher than 1250°C gave strong coloration. The rate of fading of uv-induced color increased with increasing Bi content. The fading was accelerated by heating; almost all the uv-induced color disappeared at 230°C in 30 min. The fading rate was also increased by visible light exposure. The uv-induced absorption spectra varied systematically with the composition of the tungstates.     

Effect of microstructure of titanium surface on the behaviour of osteogenic cell line MC3T3-E1

Three different microstructures were obtained on a titanium surface via immersion in HCl, H3PO4, or mixed acid of HNO3 and HF (HNO3/HF) solution. The microstructure and Rmax of the acid-treated surfaces were dependent on the acid type and immersion conditions. The growth rate of the osteogenic cell line MC3T3-E1 on each acid-treated sample, which was measured using MTT-formazan assay, was significantly higher than that of the standard which was ground with #400 SiC grit paper. Moreover, both the H3PO4 treated sample and the HNO3/HF-treated surface showed a tendency to enhance the alkaline phosphatase activity of MC3T3-E1 cells, which were grown on each acid-treated surface. These results suggest that the acid treatment of titanium is effective for the improvement of its osteocompatibility. © 1998 Chapman & Hall     

Application of Nonlinear Friction Compensation to Pneumatic Positioning

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Kinetics of Initial Sintering of Vacuum-Reduced Titanium Dioxide

Observations of sphere-to-plate bonding of vacuum-reduced monocrystalline rutile have been carried out over the temperature range 1200° to 1275°C. The rate law governing the interfacial growth between sphere and plate indicates that the predominant mechanism of material transport in this sintering process is volume diffusion. In the light of the reasonably satisfactory agreement between the oxygen self-diffusion coefficients calculated from the present sintering data and those directly observed by Haul and Just utilizing an isotopic exchange technique, it is likely that oxygen ion diffusion is the rate-determining step in the sintering experiments described.     

日本的镁合金旋压技术

镁合金是面向未来、环境友好的实用结构材料,旋转成形是环境友好的材料塑性成形技术,镁合金旋压技术是非常有必要开发研究的环境友好的金属塑性成形高新技术。本文根据所收集的公开资料,对日本近年来针对AZ31、AZ31B镁合金板材所开展的旋压成形技术的研究和开发情况进行了综述,内容包括圆筒形件旋压、车轮旋压成形、旋压缩管以及圆管端部缩口、封头旋压工艺的旋压机床、坯料条件、工件尺寸、加热温度、成形参数、工艺过程以及材料组织和性能变化等。