流变铸造AZ91-Sn合金的组织演化、拉伸行为及磨损性能

研究了不同Sn含量流变铸造AZ91合金的组织演化、拉伸行为及磨损性能。结果表明：Sn的合金化改变了Al在镁基体中的固溶度,并且显著细化了微观组织。加入0.8%（质量分数,下同）的Sn后,合金平均晶粒尺寸从105.0 μm降至42.1 μm。高熔点的金属间化合物为析出相提供了异质形核点,这些弥散析出的第二相在流变凝固过程中有效地细化了镁基体。弥散分布的第二相抑制了枝晶组织生长,从而进一步提升了合金的力学性能。随着Sn含量的增加,合金磨损率显著降低,磨粒磨损逐渐消失。3.0%Sn合金化的流变铸造AZ91合金具有最高的抗拉伸强度以及最好的耐磨损性能。     

数控机床伺服参数优化技术研究及应用

给出数控机床伺服控制系统三闭环控制结构,介绍每个控制环的控制原理。给出伺服参数优化流程,以及速度环、位置环和圆度优化的具体测试项目、伺服参数和优化方法。根据三轴立式加工中心存在的问题,进行了单轴伺服参数优化和圆度优化,给出了优化前后伺服参数和控制性能的对比。优化后三轴立式加工中心的加工节拍减少了2.3 s,圆插补加工误差减小到10 μm以内。     

Electrochemical characterization of AlPO_4 coated LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2 cathode materials for high temperature lithium battery application

Aluminum phosphate(AlPO_4) was used to modify the surface of LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2(NCM) cathode material.The surface structure and electrochemical properties of the coated materials were investigated by X-ray photoelectron spectroscopy(XPS) and electrochemical impedance spectroscopy(EIS).The results confirm the formation of aluminum-containing solid solution on the surface of NCM particles.An aluminum phosphate coating blocks the Li~+ insertion-extraction process in cells charged at high rates at room temperature,increasing surface film resistance and decreasing discharge capacity.However,an aluminum phosphate aids the formation of a stable solid electrolyte interface film on NCM surface and stabilizes the R_(ct) of cell as samples electrochemically cycled at 55℃.The electrochemical studies suggest that the initial columbic efficiency is significantly enhanced.An NCM sample coated with 1.0 wt% AlPO_4 delivers a higher discharge capacity and shows excellent capacity retention ability.     

Challenges and strategies for ultrafast aqueous zinc-ion batteries

With the rising demand for fast-charging technology in electric vehicles and portable devices,significant efforts have been devoted to the development of the highrate batteries.Among numerous candidates,rechargeable aqueous zinc-ion batteries(ZlBs) are a promising option due to its high theoretical capacity,low redox potential of zinc metal anode and inherent high ionic conductivity of aqueous electrolyte.As the strong electrostatic interaction between Zn~(2+) and host generally leads to sluggish electrode kinetics,many strategies have been proposed to enhance fast(dis)charging performance.Herein,we review the state-of-the-art ultrafast aqueous ZIBs and focus on the rational electrode-designing strategies,such as crystal structure engineering,nanostructuring and morphology controlling,conductive materials introducing and organic molecule designing.Recent research directions and future perspectives are also proposed in this review.     

Preparation and electrocatalytic properties of tungsten carbide electrocatalysts

1　ＩＮＴＲＯＤＵＣＴＩＯＮ ｉｎ 1 5 0℃ .Ｍａａｓ[1 0 ] ａｌｓｏｍａｎｕｆａｃｔｕｒｅｄｔｈｅＨ2 Ｏ2 ｆｕｅｌｃｅｌｌｓｔａｃｋｓｗｉｔｈｔｈｅｏｕｔｐｕｔｐｏｗｅｒｕｐｔｏ 1ｋＷ ,ａｎｄｔｈｅｐｒｏｐｅｒｔｉｅｓｏｆｔｈｅａｓ ｐｒｅｐａｒｅｄｆｕｅｌ     

A Complex Evaluation of the In-Vivo Biocompatibility and Degradation of an Extruded ZnMgSr Absorbable Alloy Implanted into Rabbit Bones for 360 Days

The increasing incidence of trauma in medicine brings with it new demands on the materials used for the surgical treatment of bone fractures. Titanium, its alloys, and steel are used worldwide in the treatment of skeletal injuries. These metallic materials, although inert, are often removed after the injured bone has healed. The second-stage procedure—the removal of the plates and screws—can overwhelm patients and overload healthcare systems. The development of suitable absorbable metallic materials would help us to overcome these issues. In this experimental study, we analyzed an extruded Zn-0.8Mg-0.2Sr (wt.%) alloy on a rabbit model. From this alloy we developed screws which were implanted into the rabbit tibia. After 120, 240, and 360 days, we tested the toxicity at the site of implantation and also within the vital organs: the liver, kidneys, and brain. The results were compared with a control group, implanted with a Ti-based screw and sacrificed after 360 days. The samples were analyzed using X-ray, micro-CT, and a scanning electron microscope. Chemical analysis revealed only small concentrations of zinc, strontium, and magnesium in the liver, kidneys, and brain. Histologically, the alloy was verified to possess very good biocompatibility after 360 days, without any signs of toxicity at the site of implantation. We did not observe raised levels of Sr, Zn, or Mg in any of the vital organs when compared with the Ti group at 360 days. The material was found to slowly degrade in vivo, forming solid corrosion products on its surface.     

纳米复合NdFeB永磁材料研究的新进展

综述了NdFeB纳米晶双相复合永磁材料的最新研究进展,介绍了其磁性能的研究现状,分析了其研究的发展趋势。     

首钢连退清洗段跑偏问题的治理

针对带钢连续退火生产线清洗段时常出现的带钢跑偏问题,通过将电解沉没辊的辊型改为单锥度凸度辊、定期检查辊子安装精度和辊面粗糙度、调整挤干辊压力等,切实解决了清洗段跑偏问题.     

冷轧无取向电工钢处理线新技术

介绍了国内外无取向电工钢的发展及其处理线的新技术,包括带钢脱脂清洗技术、热处理技术、涂层技术、检测技术.     

铝合金壳体铸件翻转浇注工艺研究

翻转浇注是重力浇注的一种特殊形式,它有许多优点,有利于解决复杂铸件浇注过程产生的缩孔、缩松、气孔、夹杂等铸造缺陷.对航空用铝合金壳体铸件的浇注工艺进行了研究,分析了传统重力底注铝合金壳体铸造缺陷的原因,提出了翻转浇注工艺并进行了改进.结果表明,改进后的工艺使铝合金壳体铸件的合格率增至90％,获得了无夹渣和气孔的铸件.