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71.
In this study, the dissimilar friction stir welding(FSW) butt joints between aluminum alloy 5754-H114 and commercially pure copper were investigated. The thickness of welded plates was 4 mm and the aluminum plate was placed on the advancing side. In order to obtain a suitable flow and a better material mixing, a 1-mm offset was considered for the aluminum plate, toward the butt centerline. For investigating the microstructure and mechanical properties of FSWed joints, optical microscopy and mechanical tests(i.e., uniaxial tensile test and microhardness) were used, respectively.Furthermore, the analysis of intermetallic compounds and fracture surface was examined by scanning electron microscopy and X-ray diffraction. The effect of heat generation on the mechanical properties and microstructure of the FSWed joints was investigated. The results showed that there is an optimum amount of heat input. The intermetallic compounds formed in FSWed joints were Al4Cu9 and Al2Cu. The best results were found in joints with 1000 rpm rotational speed and100 mm/min travel speed. The tensile strength was found as 219 MPa, which reached 84% of the aluminum base strength.Moreover, maximum value of the microhardness of the stir zone(SZ) was attained as about 120 HV, which was greatly depended on the grain size, intermetallic compounds and copper pieces in SZ. 相似文献
72.
《Drug development and industrial pharmacy》2013,39(7):815-821
ABSTRACTA simple and accurate high-performance liquid chromatographic (HPLC) method was developed to determine Celecoxib in capsule formulations. The drug was chromatographed on a reversed-phase C-18 column. Eluents were monitored at a wavelength of 251 nm using a mixture (85:15) of methanol and water. Solution concentrations were measured on a weight basis to avoid the use of an internal standard. The method was statistically validated for linearity, accuracy, precision, and selectivity. Due to its simplicity and accuracy, we believe that the method will be useful for routine quality control analysis. 相似文献
73.
Corrosion of steel under the defected coating in near-neutral pH solution was investigated by localized electrochemical impedance spectroscopy (LEIS) measurements. The LEIS response is dependent on the size of the defect. For small defects, e.g., less than 200 μm in diameter, localized corrosion process and mechanism of steel, as indicated by the measured LEIS plots, change with time. The diffusion process dominates the interfacial corrosion reaction, which is due to the block effect of the deposited corrosion product combined with the geometrical factor of a large coating thickness/defect width ratio. In the presence of a big defect, e.g., up to 1000 μm, the LEIS responses measured at the defect are always featured by a coating impedance in the high-frequency range and an interfacial corrosion reaction in the low-frequency range. The block effect of corrosion product does not apply due to the relatively open geometry. Conventional EIS measurements on a macroscopic-coated electrode reflect the “averaged” impedance results from both coating and defect. The information of the localized electrochemical corrosion processes and mechanisms at the small defect is lost, and the coating impedance information is “averaged” out when a big defect is contained. LEIS measurement provides an essential technique to characterize microscopically the local electrochemical corrosion reaction of steel under the defected coating. 相似文献
74.
75.
Thomas Ingram Sandra Storm Philipp Glembin Stephan Bendt Désirée Huber Tanja Mehling Prof. Dr.‐Ing. Irina Smirnova 《化学,工程师,技术》2012,84(6):840-848
Aqueous nonionic surfactant solutions split into two phases if the temperature is increased beyond a certain temperature, the so‐called cloud point temperature. Presently many different types of nonionic surfactants are produced commercially, out of these numerous have been considered as potential solvent for the cloud point extraction. In this work the crucial thermophysical properties of nonionic surfactants are investigated to determine the potential of surfactant systems for extraction processes. Phase equilibria of the binary system Triton X‐114/water and the ternary system Triton X‐114/water/phenol were measured. Based on these data the cloud point extraction was implemented in a continuous stirred extraction column. It was found, that increasing temperature within the column reduces the loss of surfactant and leads to an increasing enrichment factor. This work demonstrates that surfactant/water systems represent a suitable alternative to conventional solvents and can effectively be processed in continuous extraction columns. 相似文献
76.
77.
《分离科学与技术》2012,47(7):993-1001
A two-step protocol to remove endotoxins from recombinant human-like collagen was investigated. To meet the clinical need, Triton X-114 two-phase extraction system was applied as the first step to remove large amounts of endotoxins, while affinity chromatography was used as the second step to achieve further purification. Under the best experimental condition optimized through response surface methodology techniques, endotoxin level was 0.025?0.25 EU/mg and protein recovery was 81.9%, respectively, which indicated that 99% of endotoxins were eliminated with high protein recovery. Therefore, the two-step protocol can be exploited as an efficient method for endotoxin elimination in biotechnology processes. 相似文献
78.
结合实际生产阐述了宝鸡钢管公司资阳钢管厂在役的螺旋埋弧钢管生产线在钢管X射线检查过程中出现的问题。分析发现,钢管进管方式、射线设备及设施存在的不足会造成钢管在进行X射线检验时射线灵敏度不达标。而且X射线工业电视检测装置受到场地、设备等条件的诸多限制,操作不便,同时半开放式检测室对周围环境及人员的安全影响较大。针对这些问题,将X射线成像系统的配套设备及检测室进行了设计改造。改造后的检测系统操作便利、设备使用故障减少,设施的安全性能满足国家的辐射安全环保要求。 相似文献
79.
用环法测定了Triton X-100的临界胶团浓度(用CMC表示),并探讨不同链长及结构的脂肪醇对Triton X-100的CMC影响,利用表面化学原理讨论其现象。 相似文献
80.
该文以负载Cu2+活性炭-Co-PbO2/不锈钢-不锈钢三维电极体系处理活性艳红X-3B模拟印染废水。试验结果表明:当电解时间为30 min,电流密度为25 mA/cm2,极板间距为6 cm,氯化钠支持电解质投加量为0.2 mol/L,投加Cu2+负载量为0.5 mol/L,活性炭用量为25 mg时,处理浓度为50 mg/L的活性艳红溶液30 min时,降解率达到95.8%。该方法适用于较宽的pH范围。通过降解前后紫外可见光谱分析可以看出,随着反应的进行,活性艳红分子被彻底降解为小分子物质。 相似文献