Synthesis and Sintering of Cordierite from Ultrafine Particles of Magnesium Hydroxide and Kaolinite

Thermal reactions of magnesium compounds and kaolinite were investigated to obtain dense cordierite ceramics without additives. Magnesium hydroxide was precipitated from aqueous solution in the form of ultrafine hexagonal tabular particles of about 0.1 µm, and heating this mixture with kaolinite in a mole ratio of MgOAl₂O₃2SiO₂ resulted in formation of an amorphous state at about 900°C following thermal decomposition. µ-Cordierite was then crystallized from the amorphous phase at about 950°C, and gradually transformed into alpha-cordierite. Firing the pressed specimens yielded a dense alpha-cordierite ceramic with a relative density of 97.7% at 1350°C.     

Effect of hydrogen on martensite formation in austenitic stainless steels in high-pressure torsion

The martensitic transformation induced by high-pressure torsion (HPT) and hydrogen desorption in Type 304 and 316L austenitic stainless steels is reported in this paper. When Type 304 with only 2.2 mass ppm hydrogen was subjected to HPT, up to 95% of the austenite transformed to martensite. For Type 316L with 1.5 ppm hydrogen content, martensitic transformation during HPT was up to 50%. Martensitic transformation during HPT was suppressed by hydrogen pre-charging to <80% for Type 304 with 24.2 ppm hydrogen and <10% for Type 316L with 22.3 ppm hydrogen. This is presumed to be due to slip localization by hydrogen-enhanced slip planarity. Because of the significantly greater hydrogen solubility and lower diffusivity in austenite as compared to martensite, it is hypothesized that when hydrogen-containing austenite is transformed to martensite, excess hydrogen is released and then diffuses primarily through martensite.     

Current–Voltage Characteristics of Cobalt-Doped Inversion Boundaries in Zinc Oxide Bicrystals

Undoped and cobalt-doped basal inversion boundaries were fabricated in ZnO bicrystals to investigate their current–voltage characteristics. High-resolution transmission electron microscopy observations and energy-dispersive X-ray spectroscopy analyses for a cobalt-doped bicrystal revealed that the boundary was highly coherent and free from intergranular phases and precipitates, but a certain amount of cobalt was present near the boundary. The cobalt-doped bicrystals exhibited nonlinear characteristics that depended on cooling rates from annealing temperature, in contrast to linear characteristics of the undoped bicrystals. It is suggested that the presence of cobalt impurities enhances the formation of acceptor-like native defects near the boundaries to generate electrostatic potential barriers.     

永平铜矿不稳定边坡治理初探

本文介绍了水平铜矿以监测为先导，进行稳定性评价和分期实施应急加固，以及永久性综合治理的方法。     

高压电容自动补偿监控系统设计与实践

本文根据采矿设备冲击性负载的用电特点 ,详细阐述了 6kV高压电自动补偿监控系统的组成结构、控制原理 ,并率先将高压F -C回路应用于高压电容补偿自动投切中     

永平天排山铜硫矿床中氧化带的特征

区域性气候、地质构造和人类的行为形成了永平铜矿矿床中氧化带的分布规律及表现特征 ,掌握了这些规律和特征 ,可以因势利导 ,变不利为有利 ,指导生产实践。     

A procedure for constructing social network using Web search engines: the case for Japanese automotive industry

Recently, search engines have enabled us to access immense quantities of useful information in an instant. In this paper, we propose a procedure for analyzing the social relationship and structure using Web search engines, which includes novel ways to create a search query and to use the number of hits. This allows us to construct various networks that reflect directed and undirected relationships among actors under arbitrary contexts. As a case study for evaluations of the proposed procedure, we focus on 50 companies belonging to the automotive industry in Japan. We constructed several directed and undirected networks under different temporal and geographical contexts. It is shown that we can acquire a general understanding of the industrial community through the analyses of these created networks and their centrality measures.     

Ion beam analyses of particulate matter in exhaust gas of a ship diesel engine

There is an urgent need to reduce emission of the particulate matter (PM) in the exhaust gas from ship diesel engines causing various health hazards and serious environmental pollution. Usually the heavy fuel oil (HFO) for ships is of low quality, and contains various kinds of impurities. Therefore, the emission of PM along with exhaust gas from ship diesel engines is one of the most serious environmental issues. However, the PM fundamental properties are not well known. Therefore, it is important to perform elemental analysis of the PM. The HFO contains sulfur with a relatively high concentration of a few percent. It is important to make quantitative measurements of sulfur in the PM, because this element is poisonous for the human body. In the present work, PM samples were collected from exhaust gas of a test engine, and RBS and PIXE analyses were applied successfully to quantitative analysis of the PM samples. The RBS analysis enabled quantitative analysis of sulfur and carbon in the collected PM, while heavier elements such as vanadium and iron were analyzed quantitatively with the PIXE analysis. It has been found that the concentration ratio of sulfur to carbon was between 0.007 and 0.012, and did not strongly depend on the output power of the engine. The S/C ratio is approximately equal to the original composition of the HFO used in the present work, 0.01. From the known conversion ratio 0.015 of sulfur in the HFO to sulfates, the conversion ratio of carbon in the HFO to the PM is found to be 0.01-0.02 by the RBS measurements. On the other hand, the PIXE analysis revealed a vanadium enrichment of one order of magnitude in the PM.     

水附着对球墨铸铁拉抻性能的影响

研究了水附着对不同基体组织球铁的拉伸性能的影响，结果表明，水附着拉伸试验中，奥贝球铁、球光体球铁、淬火回火球铁的拉伸强度和伸长率同时下降，发生显著的水脆化；而铁素体球铁几乎无水脆化现象，这种水脆化现象是在超过屈服点的塑性变形中球铁表面附着水分解的氢的氢脆而导致的。