20MnCr5圆棒锯切困难原因分析

某厂在锯切20MnCr5圆棒过程中锯条容易断裂，采用光学显微镜(OM)和扫描电子显微镜(SEM)等观察分析手段，对锯条容易断裂的原因进行分析。分析结果表明：锯条断裂的原因为加工20MnCr5过程中粘刀崩齿。针对此类加工缺陷，提出了相应的改进措施。     

Effect of microstructural features on the corrosion behavior of severely deformed Al–Mg–Si alloy

The aim of this study was to determine the influence of severe plastic deformation processing and the changes in microstructure resulting therefrom on the corrosion resistance of an Al–Mg–Si alloy. The alloy was processed using incremental equal channel angular pressing, which caused a reduction in grain size from 15 to 0.9 µm. The grain refinement was accompanied by an increase in the number of grain boundaries and dislocations, and by changes in grain orientation. However, there was no change in the size and number of intermetallic particles, which presumably resulted in a constant number of galvanic couplings. Electrochemical experiments revealed only slight differences between the samples before and after processing. Higher potential transients/oscillations upon immersion and increased corrosion currents in the vicinity of corrosion potential point to slightly higher reactivity of the most refined material. This indicates that intermetallic particles are the most crucial microstructural elements in terms of corrosion resistance. Their impact exceeds that of grain boundaries, in particular, at the stage of corrosion initiation. The development of corrosion attack is controlled more by the microstructure of the matrix as the grain refinement resulted in a less pronounced corrosion attack in comparison with the coarse-grained sample.     

Superhydrophobic aluminum alloy surface with excellent universality,corrosion resistance,and antifouling performance prepared without prepolishing

It is urgently necessary to seek more simple and effective methods to construct superhydrophobic metal surfaces to improve the corrosion resistance and antifouling performance. Herein, a facile method for fabricating superhydrophobic aluminum alloy surface is developed via boiling water treatment and stearic acid modification. It is noteworthy that no prepolishing on aluminum alloy is required and no caustic reagents and typical equipments are used during the preparation procedure. Therefore, the fabrication method is quite a simple and environment-friendly technique. Both micro- and nano-scaled binary structure forms at the resultant aluminum alloy surface while long alkyl chains are grafted onto the rough aluminum alloy surface chemically. Consequently, the resultant aluminum alloy exhibits outstanding superhydrophobicity. More importantly, the superhydrophobicity has excellent universality, diversity, stability, excellent corrosion resistance, and antifouling performance. The facile preparation, excellent superhydrophobic durability, and outstanding performance are quite in favor of the practical application.     

基于MF-DCCA 的呼吸道疾病与大气污染物相关性分析

针对呼吸道系统疾病与大气 PM2:5、 SO2 浓度序列的相关性特征, 应用多重分形消除趋势波动分析法 (MF-DCCA), 对张家界市永定区呼吸道系统疾病患病人数与大气 PM2:5、 SO2 浓度序列进行了研究。结果发现该地区 呼吸道系统疾病患病人数与大气 PM2:5、 SO2 浓度的相关性具有长期持续特征和多重分形特征。随后对它们相关性 多重分形特征的动力来源进行了分析, 通过随机重排和相位随机处理, 结果表明在不同时间尺度上的长期持续性影响 是其主要动力来源。进一步研究发现该地区呼吸道系统疾病与大气 PM2:5、 SO2 浓度序列的相关性在四个季节均具 有长期持续性的多重分形特征, 且夏季多重分形特征相对强于其他季节。     

基于IEC 60870-5-104协议的调度命令发送方法研究

对IEC 60870-5-104协议的调度命令进行了研究，提出了一种基于现有IEC 60870-5-104协议的调度命令发送新方法。此技术充分利用了IEC 60870-5-104协议的文件发送功能，通过远程终端单元（RTU）向电厂发送包含调度命令的文本文件。考虑到调度命令在电力系统和电力市场结算系统安全方面的重要性，将该方法应用在电网调度自动化 SCADA 系统中，可以实现交换数据的更高可用性。     

In Vivo Albumin-Binding of a C-Functionalized Cyclam Platform for 64Cu-PET/CT Imaging in Breast Cancer Model

An improved glucose-chelator-albumin bioconjugate (GluCAB) derivative, GluCAB-2^Mal, has been synthesized and studied for in vivo ⁶⁴Cu-PET/CT imaging in breast cancer mice models together with its first-generation analogue GluCAB-1^Mal. The radioligand works on the principle of tumor targeting through the enhanced permeability and retention (EPR) effect with a supportive role played by glucose metabolism. [⁶⁴Cu]Cu-GluCAB-2^Mal (99 % RCP) exhibited high serum stability with immediate binding to serum proteins. In vivo experiments for comparison between tumor targeting of [⁶⁴Cu]Cu-GluCAB-2^Mal and previous-generation [⁶⁴Cu]Cu-GluCAB-1^Mal encompassed microPET/CT imaging and biodistribution analysis in an allograft E0771 breast cancer mouse model. Tumor uptake of [⁶⁴Cu]Cu-GluCAB-2^Mal was clearly evident with twice as much accumulation as compared to its predecessor and a tumor/muscle ratio of up to 5 after 24 h. Further comparison indicated a decrease in liver accumulation for [⁶⁴Cu]Cu-Glu-CAB-2^Mal.     

Influence of aluminum phosphate on the tribocorrosion performance of chemically bonded phosphate ceramic coatings

In this study, chemically bonded phosphate ceramic coatings (CBPCCs) with different contents of aluminum phosphate (AP) are prepared on stainless steel (AISI 304L). Differential scanning calorimetry, X-ray diffraction, contact angle test, and a tribocorrosion experiment are carried out to clarify the role of AP in the tribocorrosion performance of CBPCCs. The results show that, with the increase in the AP content, the enthalpy of curing increases because of the greater formation of the bonding phase AlPO₄. Both in static corrosion and in tribocorrosion, the corrosion current density of CBPCCs achieves the lowest value when the weight ratio of AP to polytetrafluoroethylene is about 0.78. Additionally, the influence mechanism of AP on tribocorrosion is clarified. AlPO₄ from the reaction between AP and Al₂O₃ has excellent mechanical properties and can enhance the wear resistance of CBPCCs by reducing the mechanical wear and the increased wear due to corrosion. The alumina particles wrapped by AlPO₄ can form a dense and smooth surface and change the direction of electrolyte propagation, which leads to the increase in the tribocorrosion resistance of CBPCCs.     

Microstructure and electromagnetic properties of LiFe5O8 ferrite ceramics prepared from wet- and dry-milled powders

The effect of dry and wet ball milling of LiFe₅O₈ ferrite powder on the microstructure and electromagnetic properties of ferrite ceramics was studied using XRD analysis, scanning electron microscopy, dilatometry, thermogravimetry, calorimetry, and measurement of specific magnetization and electrical resistance. The sintering temperature was 1050 °C; the sintering time was 2 h. It was found that ferrite fabricated from dry-milled powder exhibits an ordered α-LiFe₅O₈ phase with bulk density of 91%. Its saturation magnetization and Curie temperature are 55 emu/g and 628°С, respectively. Specific electrical resistance is 4?10⁶ Ω cm. Wet milling in isopropyl alcohol causes formation of a disordered β-LiFe₅O₈ phase. Ceramics produced by this method shows higher bulk density (97%) and low porosity, and an order of magnitude lower resistivity. Its saturation magnetization and Curie temperature are 51 emu/g and 607°С, respectively.     

Interfacial microstructure and mechanical properties of Ti3SiC2 ceramic and TC11 alloy joint diffusion bonded with a Cu interlayer

Reliable joints of Ti₃SiC₂ ceramic and TC11 alloy were diffusion bonded with a 50 μm thick Cu interlayer. The typical interfacial structure of the diffusion boned joint, which was dependent on the interdiffusion and chemical reactions between Al, Si and Ti atoms from the base materials and Cu interlayer, was TC11/α-Ti + β-Ti + Ti₂Cu + TiCu/Ti₅Si₄ + TiSiCu/Cu(s, s)/Ti₃SiC₂. The influence of bonding temperature and time on the interfacial structure and mechanical properties of Ti₃SiC₂/Cu/TC11 joint was analyzed. With the increase of bonding temperature and time, the joint shear strength was gradually increased due to enhanced atomic diffusion. However, the thickness of Ti₅Si₄ and TiSiCu layers with high microhardness increased for a long holding time, resulting in the reduction of bonding strength. The maximum shear strength of 251 ± 6 MPa was obtained for the joint diffusion bonded at 850 °C for 60 min, and fracture primarily occurred at the diffusion layer adjacent to the Ti₃SiC₂ substrate. This work provided an economical and convenient solution for broadening the engineering application of Ti₃SiC₂ ceramic.     

High dielectric constant of NiFe2O4–LaFeO3 nanocomposite: Interfacial conduction and dielectric loss

Materials exhibiting colossal dielectric constant are the most sought-after materials due to their variety of applications in various electronics industries. NiFe₂O₄ and LaFeO₃ belonging to the spinel and perovskite structures, respectively, were coupled into a nanocomposite by adapting a one-pot sol-gel synthesis. The ratio of NiFe₂O₄:LaFeO₃ was varied and the synthesized materials were studied for their dielectric behaviors. Interestingly, among the samples studied, the nanocomposite with the ratio of 1:2 of NiFe₂O₄–LaFeO₃ exhibited a high dielectric constant value of 10390 at a frequency of 1 kHz with a several-fold increase in conductivity. The high conductivity resulted in a high dielectric loss. The origin of such a high dielectric constant and loss have been attributed to the Maxwell-Wagner type space charge polarization arising from the microstructure that consists of large and continuous grain boundaries, and the conducting phase at the interface, respectively.