Influence of peening on the corrosion properties of AISI 304 stainless steel

The effects of peening treatment on the microstructure and corrosion behavior of AISI 304SS were investigated. Shot and ultrasonic peening were performed on the austenitic stainless steel, and peened specimens were compared in terms of microstructure, surface roughness and corrosion resistance. Nano-sized grains, multi-directional mechanical twins and strain-induced martensite were formed on the surfaces, and the volume fraction of strain-induced martensite in the ultrasonically peened specimen was higher than that of the shot-peened specimen. The ultrasonically peened specimen which had smoother surface and contained more strain-induced martensite showed superior general and localized corrosion resistance to the as-received and shot-peened specimens.     

Displacement and Luminescence of Eu~(3 ) in CaYBO_4

Ａｇｒｅａｔｄｅａｌｏｆｉｎｖｅｓｔｉｇａｔｉｏｎｈａｓｂｅｅｎｃａｒ ｒｉｅｄｏｕｔｏｎｔｈｅｌｕｍｉｎｅｓｃｅｎｃｅｏｆＥｕ3 ｉｎｍａｎｙｈｏｓｔｓ,ｓｕｃｈａｓｔｈｅｃｏｍｍｅｒｃｉａｌｒｅｄｐｈｏｓｐｈｏｒＹ2 Ｏ3∶Ｅｕ ,ｗｈｏｓｅｌｕｍｉｎｅｓｃｅｎｔｑｕａｎｔｕｍｅｆｆｉ ｃｉｅｎｃｙｈａｓａｔｔａｉｎｅｄｎｅａｒｌｙ 1 0 0 %ｕｎｄｅｒ 2 5 4ｎｍｅｘｃｉｔａｔｉｏｎ .Ｉｔｉｓａｌｓｏｔｈｅｈｉｇｈｅｓｔｑｕａｎｔｕｍｅｆｆｉ ｃｉｅｎｃｙｏｆａｌｌｔｈｅｃｏｍｍｅｒｃｉａｌｐｈｏｓｐｈｏ…     

超声冲击强化对TC4钛合金拉压疲劳性能的影响

静荷载25 N、振幅30μm、冲击数36 000次/mm2下对TC4钛合金去应力退火及固溶时效两种状态进行超声表面冲击强化处理,研究其对TC4拉压疲劳性能的影响。对处理后的微观组织、硬度、强塑性变形(SPD)层、残余应力、疲劳性能和断裂特征进行分析。结果表明:处理后在TC4表面均获得约40μm深的强塑性变形层、表面硬度及残余压应力均被提高、表面粗糙度有较好的维持、两种状态的108周次的疲劳强度分别提升7.0%和10.7%;10~6周次前裂纹主要由表面萌生,10~6周次后裂纹源核心表现为SPD层与核心之间的变形α相,其形状狭长且平行于试件边缘。建立经典材料力学模型对其轴向应力进行分析,有助于理解内部裂纹源。     

Gibbs Free Energies of Formations of the Magnesium and Calcium Germanates at High Temperatures

The relative chemical potentials and partial molar solution enthalpies of the quasi-binary systems MgO-GeO₂ and CaO-GeO₂, were determined by means of solid-state galvanic cells and high-temperature solution calorimetry, respectively. The standard free energies of formation of the corresponding germanates, MgGeO₃, CaGeO₃, CaGe₄O₉, are presented as a function of temperature.     

Application of Electrochemical Quartz Crystal Microbalance Technique to Hydrogen/Lithium Insertion into MnO2/LiCoO2 Electrode in Aqueous/Non-aqueous Solution

The hydrogen insertion/desertion into/from MnO₂ electrode in aqueous solution and the lithium intercalation/ deintercalation into/from LiCoO₂ electrode in non-aqueous solution have been investigated by usingin-situ electrochemical quartz crystal microbalance (EQCM) technique combined with cyclic voltammetry (CV) and galvanostatic charge-discharge experiment. In the case of the MnO₂ electrode, the combined cyclic electrogravimetric and CV results indicated that the redox potentials at the transition in oxidation state of manganese ion measured on the cathodic scan are satisfactorily in accord in value with those thermodynamic e-quilibrium potentials calculated in Pourbaix diagram. The positive/negative slope with a constant value in the plot of mass change rate vs. potential means that the reaction is inclined to proceed in the direction of an oxidation/reduction between two phases. From the electrogravimetric curves obtained simultaneously with galvanostatic discharge curves, the discrepancy between the charge and mass variations was discussed in relation with the hydrogen-induced stress. In the case of the LiCoO₂ electrode, the cyclic electrogravimetric data obtained simultaneously with CV indicated that neither solvent nor any of other species but lithium ions are intercalated into and deintercalated from the electrode. From the cyclic electrogravimetric curve obtained simultaneously with galvanostatic charge-discharge curve, the discrepancy between the charge and mass variations was discussed in relation with the change of the molar volume and surface roughness of the electrode during the lithium intercalation and deintercalation.     

Inactivation of Lactobacillus plantarum by Pulsed-Microwave Irradiation

Suspensions of Lactobacillus plantarum cells were subjected to either conventional heating, continuous microwave (CW) or pulsed microwave (PW) irradiation at 50°C for 30 min. Samples exposed to PW showed greater reductions (2 ～ 4 log) in survival counts than those treated with either conventional heating or CW irradiation. As exposure time increased, PW resulted in a remarkable increase in 260 nm-absorbing compounds that leaked into the suspending menstruum, as compared to CW or conventional heating, indicating that PW irradiated cells were the most injured. The growth of PW irradiated cells was delayed about 24h and the final acidity of the culture broth was about 60 ～ 80% that of other cells treated with conventional heating or CW irradiation.