Microstructure,mechanical properties and wear resistance of an Al–Mg–Si alloy produced by equal channel angular pressing

Microstructure, mechanical properties and wear resistance in an ultrafine-grained Al–Mg–Si alloy fabricated utilizing a combination of equal channel angular pressing (ECAP) and dynamic aging were investigated in this paper. The results indicated that the grain size of the ECAP alloy was significantly refined, i.e., to ~239 nm after three ECAP passes. Meanwhile, the yield and tensile strength of the ECAPed material reached 340 MPa and 445 MPa, respectively, while maintaining a significant uniform elongation of 14%. Wear resistance results demonstrated that the wear rate, wear depth and width of the ECAPed material decreased in comparison with the solution-treated (SST) and peak-aged (T6) conditions under a load range of 5–25 N. The adhesive wear that occurs in the undeformed specimens at 10 N does not appear in the ECAPed specimen at the same load, indicating that the ECAPed specimen delay the appearance of more serious wear mechanisms under certain loads. The cooperative interaction of high density nano-scale β" precipitates and dislocations resulted in a combination of super-high strength and good work hardening ability which suppressed the extension of cracks between the friction layer and the plastic deformation zone. As a consequence, the combination of ECAP and dynamic aging brings a significant improvement for antifriction performance of the 6061 aluminum alloy.     

Effect of heat treatment on microstructures and properties of a novel Al-Zn-Mg-Cu alloy for oil drilling

In view of the special requirements for strength, heat resistance and corrosion resistance of Al-Zn-Mg-Cu alloy for oil drilling, the Al-6.2 Zn-2.5 Mg-1.6 Cu alloy was prepared by increasing Cu content on basis of Russian Series 1953 alloy. The effect of heat treatment on the microstructures and properties of the alloy was characterized by optical microscope(OM), scanning electron microscope(SEM) and transmission electron microscope(TEM), and investigated by tensile test at room temperature, thermal exposure test and corrosion test. The results show that the strength after T6 aging treatment exhibit a decrease trend as an increase of the solution temperature from465 °C to 480 °C. After the solution treated by the rate of 470 °C/1 h, second phases dissolve into the matrix very well and the strength property reaches optimum. The alloy has better comprehensive properties treated by a solution treatment of 470 °C/1 h and then followed by an aging treatment of 120 °C/24 h + 170 °C/1 h + 120 °C/24 h. Under the aging state, the precipitated phases inside the grains are suitable in size, while on the grain boundary distribute discontinuously and the precipitate-free zone is obvious. Besides, the alloy still maintain high tensile properties. The yield strength, tensile strength and elongation are 650 MPa, 686 MPa,12.0%, respectively. The yield strength retention after heat exposure is 92%. The alloy has good corrosion resistance and the exfoliation corrosion degree. The average corrosion rate in the H_2S and CO_2 environment is 0.0024 mm/a, which is far less than the required 0.12 mm/a. It is insensitive to H_2S and CO_2 environments.     

智能高速罐身电阻焊机数字化控制系统

提出了以国产MCT80 0 0F8运动控制器为核心的智能高速罐身电阻焊机数字化控制系统 ,并介绍了系统的组成、工作原理、硬件接口、电机控制方法以及伺服电机的运动关系数学模型 .新的系统有利于提高罐身电阻焊机的制罐生产速度 ,并具有功能全面、可靠性高、控制精确、开放性好以及成本较低等优点     

交变磁场对磁性磨粒的作用分析

对处于交变磁场作用下的磁性磨料颗粒的受力和运动规律进行了分析和描述，为交变磁场作用下的磁粒研磨光整加工技术提供了新的思路和工艺选择。     

PLC在磁场压力机中的应用

提出一种采用PLC控制的压制钕铁硼(Nd-Fe-B)磁性材料的机电一体系统，并介绍了系统重要组成部分：压机主体和电控箱，给出了电控箱中各控制部分的电路及工作原理。实验证明本系统具有结构紧凑、操作方便、控制性能好等优点。     

NIPA类共聚温敏水凝胶中水的状态和耐热性

用N-异丙基丙烯酰胺（NIPA）与丙烯酸钠（SA）及甲基丙烯酸钠（SMA）共聚合成了两个系列的水凝胶，研究了共聚组成与水凝胶基本性质的关系，并用示差扫描量热法（DSC）和热失重法（TG）研究了此类水凝胶中水的状态和耐热性。     

磁存储的研究现状及发展方向

磁性存储是最常用的大容量存储技术。其记录密度越来越高，发展也越来越快。通过对信息记录、读出和存储3个过程的分析，对硬磁盘记录、垂直磁记录和磁光记录的优缺点作了对比。指出了采用垂直记录模式、非晶结构合金薄膜或铁氧体薄膜介质是实现超高密度记录的方向，光辅助磁记录是很有希望的记录技术。还指出量子磁盘技术是未来极高密度记录的方向。     

关于差分式放大器输入电阻的研究

差分式放大器在实际应用方面非常广泛,其理论分析方法的深入研究,对生产实践和教学都有重要的意义。采用电路理论分析、差放理论分析、“虚短”理论分析及实验的方法对差分式放大电路进行了研究。     

Science Letters： A synthetic Toll-like receptor 2 ligand decreases allergic immune responses in a mouse rhinitis model sensitized to mite allergen

It has been proposed that activation of Toll-like receptors （TLRs） plays crucial roles in the polarization of adaptive immune responses. A synthetic Toll-like receptor 2 （TLR2） ligand, Pam3CSK4, has been reported to modulate the balance of Th1/Th2 responses. We evaluated the modulation effect of Pam3CSK4 on allergic immune response in a mouse rhinitis model sensitized to house dust mite allergen （HDM）. Mice were sensitized and challenged with Dermatophagoidesfarinae allergen （Der f）, and then the allergic mice were treated by Pam3CSK4. Nasal allergic symptoms and eosinophils were scored. Der f-specific cytokine responses were examined in the splenocytes and bronchoalveolar lavage fluid （BALF）. Serum level of total IgE was also detected. After establishing a mouse allergic rhinitis model with HDM, we have showed that Pam3CSK4 treatment not only ameliorated the nasal allergic symptoms remarkably but also decreased the eosinophils and total inflammation cells in BALF significantly. Analysis of cytokine profile found that IFN-7 released from either BALF or stimulated splenocytes increased markedly in Pam3CSK4-treated mice, while IL-13 decreased significantly. Moreover, serum level of total IgE was significantly lower in Pam3CSK4-treated mice than in the untreated. Thus, in an allergic rhinitis mouse model developed with HDM, Pam3CSK4 was shown to exhibit an antiallergic effect, indicating its potential application in allergic diseases.     

高贵心灵的无声抗争——《女勇士》与《红字》两则故事相似性之比较

华裔美国女作家汤婷婷的作品《女勇士》中无名女人的故事与美国19世纪浪漫主义小说家纳塞尼尔·霍桑的代表作《红字》中海斯特·白兰的故事都是有关通奸的故事，虽写于不同的时代，但两个故事有着惊人的相似性。本文从两个故事的发生原因，结果以及两位女主人公对通奸行为的态度三个方面简要分析两种通奸行为，旨在阐明通奸行为是两个女人对自由和爱情的追求以及她们对当时父权社会的反抗。