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991.
The corrosion behavior of Cu–Al and Cu–Al–Be (0.55–1.0 wt%) shape-memory alloys in 0.5 M H2SO4 solution at 25 °C was studied by means of anodic polarization, cyclic voltammetry, and alternative current impedance measurements. The results of anodic polarization test show that anodic dissolution rates of alloys decreased slightly with increasing the concentrations of aluminum or beryllium. Severe intergranular corrosion of Cu–Al alloy was observed after alternative current impedance measurement performed at the anodic potential of 0.6 V. However, the addition of a small amount of beryllium was effective to prevent the intergranular corrosion. The effect of beryllium addition on the prevention of intergranular corrosion is possibly attributed to the diffusion of beryllium atoms into grain boundaries, which in turn deactivates the grain boundaries. 相似文献
992.
993.
994.
A two-dimensional polarization interferometry based parallel scan angular surface plasmon resonance biosensor 总被引:1,自引:0,他引:1
We describe a two-dimensional polarization interferometry based parallel scan angular surface plasmon resonance (SPR) biosensing technique. The method of line-shaped light illumination and parallel scan offers a high throughput. The simultaneous record of SPR angular spectrum enables the system to be unaffected by the time-dependent variation of the light source. The polarization interferometry technique lowers the minimum of the SPR dip and thereby reduces the noise related to the light intensity. Refractive index resolutions of 1.4 × 10(-6) refractive index unit (RIU) under normal condition and 4.6 × 10(-7) RIU under a more time-consuming condition are achieved in our angle interrogation based sensor. Meanwhile, a manually prepared DNA microarray has been detected, showing the potential applications of this technique in microarray analysis. 相似文献
995.
996.
高压水射流清洗技术近年来在国内得到普遍应用,但多为人工手动操作。介绍了两种典型工件的自动化清洗方案,自动化作业可有效避免人工操作的缺陷,提高工作效率和工作质量。 相似文献
997.
One purpose of the present study is to evaluate the tribological behavior of a fast-carbonized (1000 °C/min) C/C composite. One other purpose of the study is to enhance the tribological performance of the composite by applying a post-treatment comprising re-impregnation of a carbonaceous additive-doped liquid precursor. The results indicate that average coefficient of friction (COF) values of non-post-treated composites prepared with three different carbonization rates (1, 100 and 1000 °C/min) are similar (0.40-0.45). The average wear rate of samples carbonized at 1000 °C/min is about twice as large as samples carbonized at 1 and 100 °C/min. Great majority of the samples demonstrate an increase in density and a decrease in porosity after the post-treatment. Pitch-group samples generally have larger changes in density and porosity than furan-group samples. After the post-treatment, all samples demonstrate decreases in both COF and specific wear rate coefficient. Pitch-group samples generally exhibit lower wear rate than furan-group samples. Samples post-treated with pitch/carbon black and pitch/mesophase pitch demonstrate the lowest wear rates among all samples tested (only half that of untreated samples carbonized at 1 °C/min), while still maintaining relatively high COF values (close to 0.4). These results indicate that an appropriate post-treatment, especially a pitch treatment, may dramatically improve the tribological performance of fast-carbonized C/C composite. 相似文献
998.
C60自组装单分子膜的制备及其磨擦特性 总被引:3,自引:2,他引:3
利用胺基与C60分子的加成反应,在3-胺基丙基-三乙氧基硅烷(APS)的自组装单分子膜(SAMs)表面上成功的制备了与基底化学键结合的C60-SAMs.其表面水接触角约为76°,膜厚约为1.15 nm,AFM形貌像显示其表面光滑、均匀,基本不含缺陷.摩擦学结果表明,APS自组装单分子膜由于其分子链短,膜的有序性差,表面颗粒聚集物及"针孔"等缺陷多,而不具有润滑作用.当在其上形成C60单分子层膜后,表现出优异的摩擦学性能,摩擦系数约为0.09~0.13,在给定实验条件下抗磨损寿命大于10 000次,有望作为微型机械的边界润滑材料使用. 相似文献
999.
光镊通过使用经过高数值孔径聚焦后的激光可以对大小从约25nm到100μm范围内的微粒进行三维微操纵.通过使用光镊测量了微小粒子在激光作用下的轴向力,并且对影响捕获效率的一些因素进行了分析.对轴向捕获力与不同激光束腰半径以及不同折射系数之间关系做了讨论. 相似文献
1000.
Su-Hai Hsiang Jer-Liang Kuo 《The International Journal of Advanced Manufacturing Technology》2005,26(9-10):970-977
This study establishes the database concerning magnesium alloy hot extrusion, and uses it to conduct various investigations. Firstly, artificial neural networks (ANN) analysis is used to determine the die shapes of various extrusion ratios. Secondly, the process parameters for the hot extrusion of magnesium alloy are determined, and thirdly, the tensile strength and maximum extrusion load of the finished product are predicted. The database includes 11 parameters, associated with 108 sets of experiment, determined by material type (AZ31 and AZ61), extrusion ratio (14.41, 35.9 and 55.85), product shape (tubular and sheet), semicone angle of the die (90° and 30°), extrusion speed, temperature to which the billet is heated, temperature to which the container is heated, lubricant, hold-time at a specified temperature, extrusion load and tensile strength. ANN is applied to learn from this database, and backward propagation analysis is conducted to find the mechanical properties of the products under various extrusion ratios. This study adopts the orthogonal array of the Taguchi method to hot extrusion experiments that involve dies with different extrusion ratios, and sets the tensile strength and extrusion load of the finished product as the quality characteristics, to acquire the optimal parameter condition. Then, based on the results obtained from the additive model, confirmatory experiments are performed. An Analysis of Variance (ANOVA) analysis is then performed to investigate and analyze the influence of factors on the hot extrusion process. The weight of important factors in the database is increased, and subsequently, the forming load and mechanical properties of magnesium alloy under extrusion are accurately predicted. 相似文献