Al对含P,Mo奥氏体不锈钢应力腐蚀性能的影响

用点焊接试验方法评价了合金元素Ａｌ对含Ｐ和Ｍｏ奥氏体不锈钢应力腐蚀破裂性能的影响。结果表明，单独添加Ａｌ没有改善应力腐蚀破裂性能，而复合添加Ａｌ和Ｃｕ有效地提高了抗应力腐蚀性能。１４Ｃｒ－１６Ｎｉ－２Ｃｕ－３Ａｌ钢中添加Ｍｏ，虽然降低应力腐蚀性能，但影响较小。含０．３％Ｍｏ时应力腐蚀破裂临界温度可达１２０℃。ＡＥＳ分析表明，Ａｌ和Ｃｕ元素在表面膜中富集。Ａｌ和ｃｕ的联合作用使钢表面膜的钝化能力得到加强，从而提高了抗应力腐蚀性能。     

Solubility and diffusivity of oxygen in aqueous sucrose solutions

Solubility and diffusivity of oxygen in aqueous sucrose solutions of various concentrations were measured at temperatures from 15° to 45°C and at atmospheric pressure. The solubility of oxygen could be correlated well by the method of van Krevelen and Hoftijzer. The diffusivity of oxygen was found to be proportional to the ?2/3 power of the viscosity of the solution.     

Advantages of counter-current operation for hydrodesulfurization in trickle bed reactors

The deep desulfurization of oil fraction is a central matter of concern to every refinery. Hydrogen sulfide is the product of hydrodesulfurization reaction and it is the inhibiter of the reaction. When products inhibit the reaction, the counter-current operation is expected to have an advantage over the co-current operation. Hydrodesulfurization of vacuum gas oil in a trickle bed reactor was simulated for both models of co-current operation and counter-current operation. The models were simulated on high and low gas and liquid velocities. Hydrogen sulfide was affected by mass transfer resistance in both gas-liquid and liquid-catalyst interface. The other component mass transfer resistances were negligible. When the deep desulfurization was required, simulation results showed that the counter-current operation was superior to the co-current operation in organic sulfur conversion     

Reduction of germination frequency in Anabaena akinetes by sediment drying: a possible method by which to inhibit bloom formation

The effect of desiccation on germination frequency of Anabaena akinetes was investigated to evaluate the practical usefulness of sediment drying in reservoirs as a measure of inhibition of Anabaena bloom formation. Sediment samples taken from a small reservoir, where an abundance of Anabaena blooms occur every summer were desiccated in the outdoors and in an incubator at 5, 10, 15, and 25 °C. As a result, the germination frequency of Anabaena akinetes was strongly inhibited in comparison with that of Anabaena akinetes preserved in a refrigerator without desiccation as a control. Greater inhibition of Anabaena germination found at a higher temperature was examined, and almost all akinetes lost the ability of germination at 25 °C after 3 days of the desiccation treatment. Therefore, sediment drying is considered to be a useful measure to reduce periods and scales of Anabaena blooms, and its effect will be enhanced by performance during the warmer seasons.     

Characteristics of neutralization of acids by newly isolated fungal cells

Soil microorganisms play an important role in maintaining soil pH at levels suitable for other soil organisms. To clarify the biological neutralization mechanism in soil, we isolated soil microorganisms showing a high ability to neutralize acids and studied their characteristics. From our taxonomic study, three isolated strains were identified as filamentous fungi, namely Mucor sp., Aspergillus fumigatus, and Aureobasidium pullulans. These strains could secrete basic materials, such as ammonia, for neutralization, grow in the medium at pH 4.0 and increase the pH of the medium to approximately 8.0. These microbial cells could neutralize not only nitric acid but also sulfuric and hydrochloric acids. The strains could also grow by utilizing nitric acid as a sole nitrogen source. In the soil containing these organisms, the pH was maintained in the neutral range by the buffering action of basic materials that they secrete. These results suggest that these fungal cells are useful for protecting the soil from acidification by acid rain.     

Kinetic parameters of the electrode reaction of chloropenta-amminecobalt(III) ions at a gold electrode

The cathodic reduction of chloropenta-amminecobalt(III) ions at active gold electrodes has been studied in 0.1 M HClO₄ + 0.1 M NaClO₄ by means of the potentiostatic method. Chloropentaamminecobalt(III) ions gave one irreversible reduction wave in the double layer potential region of gold electrodes. The kinetic parameters of the electrode reaction were measured at 5, 15, 25, 35 and 45°C, and the activation energy was calculated to be 19 kcal mol^?1 for the electron transfer process and 4.5 kcal mol^?1 for the diffusion process.     

Contact and interconnect formation on compound semiconductor devices by ionized-cluster beam deposition

A new deposition technology, namely the ionized-cluster beam deposition method, was applied to form contacts and interconnects on III–V compound semiconductor devices. Au alloy films deposited by this technology had strong enough adhesion to an insulator layer to be a satisfactory interconnection. A step approximately 8 μm high at an angle of 90° to the semiconductor was covered fully with an Au alloy film obtained by this method. Electrical ohmic contacts for p-type GaP and GaAs were successfully obtained at substrate temperatures of 400 °C and 300 °C respectively without any further annealing process; this resulted in better device characteristics because of the lower process temperatures and also made the device less expensive because of a reduction in fabrication time.     

Grazing exit electron probe microanalysis of submicrometer inclusions in metallic materials

Grazing exit electron probe microanalysis (GE-EPMA) is a new method of EPMA in which characteristic X-rays emitted from only near-surface regions of a specimen are detected at extremely low exit angles near 0 degrees (the grazing exit condition). This technique requires the analytical objects exist on a flat surface. Therefore, the GE-EPMA analysis has been used only for the analysis of particles or a thin film on a flat substrate so that there were only few applications for practical analysis. As a new application, we have carried out GE-EPMA analysis of approximately 0.2-microm inclusions on stainless steel, which appeared to be a projection on the specimen surface with chemical etching. The GE-EPMA quantitative results were in excellent agreement with those of inclusions that were extracted from the stainless steel and analyzed by EPMA with conventional exit condition (30 degrees). This method could be, therefore, applied to the analysis of the submicrometer inclusion in a wide variety of metallic materials if the inclusion appears to be a projection with chemical etching treatment.