Improved model and 3D simulation of densification process for iron powder

A new model for describing the compaction process of iron powder was proposed based on the continuum hypothesis and elliptical yield criterion. To simulate the densification behaviour, the constitutive model was implemented in Marc computer program. For the relationship between load and displacement, different models were compared and the influence of the parameters in the constitutive equations was determined by means of simulation and experiments. The density distribution of a balancer was measured and simulated. The results show that the parameter η adopted plays a modification role for the load-displacement curve, and compared with other models the present model fits better with the experimental data in the later stage of the compaction process mainly due to the different parameters A and B. The friction on the contact surface contributes to the inhomogeneous density distribution under large deformation of the workpiece. The comparison between the simulation and experimental data indicates that this model can be used to predict the powder compact process precisely and effectively.     

西北地区铁塔基础混凝土塑料薄膜养护工艺

根据西北地区气候特点,采取塑料薄膜对基础混凝土予以养护。养护后混凝土表面质量美观,满足质量工艺要求,值得以后在西北地区铁塔基础混凝土养护施工借鉴。     

薄型电工纯铁零件磁性热处理工艺研究

本文介绍了继电器用厚度小于等于0.8mm的电工纯铁零件在磁性热处理中存在的问题及解决方法,详细论述了磁性热处理方法及适用条件。     

混凝电解气浮-吸附过滤处理洗染废水

采用混凝电解气浮-吸附过滤法处理洗染废水.试验结果表明:混凝电解气浮过程中,采用石墨作阴极,铁作阳极,电解电压一般控制在8~11 V,电能消耗约0.08 kW h/m3,CODC r可去除30%以上;吸附过滤过程选用新鲜粉煤灰作为吸附材料,粒度为0.3 mm,废水在吸附柱中的停留时间为2 h,CODC r可以去除50%以上.     

车用永磁同步电机的铁耗与瞬态温升分析

为了提高车用永磁同步电机的短时过载能力和功率密度,利用有限元方法进行了综合考虑电磁、热和控制策略的损耗和瞬态温升的非线性仿真分析.损耗分析指出了铁耗由于弱磁的原因在基速附近就达到了最大;峰值工况下的铜耗在整个速度范围内基本不变;连续工况下的铜耗最大值也同样因弱磁的需要而出现在最大工作转速.瞬态温升分析表明绕组端部温度最高而成为薄弱环节;短时工作时永磁体的温度比绕组低但连续或循环工作时两者温度相差不大;增加水流量对绕组温升的影响有限,特别是短时峰值工作的影响就更小,水冷电机加强散热能力的方法在于加强材料应用和工艺改进.     

晶体硅中的铁沉淀规律

研究了在直拉单晶硅和铸造多晶硅中经110 0℃热处理快冷或慢冷条件下所形成的铁沉淀规律及其对少数载流子扩散长度的影响.红外扫描仪照片显示在直拉单晶硅中慢冷却形成的铁沉淀密度较低,而且其尺寸较大;在铸造多晶硅中,铁易在晶界上沉淀,沉淀规律也依赖于冷却速度.表面光电压仪测试结果表明:无论在直拉单晶硅材料中还是在铸造多晶硅材料中,快冷形成的铁沉淀对少数载流子扩散长度影响更大.实验结果可以用铁沉淀生成的热力学和动力学规律解释     

铁基合金粉末激光熔覆的显微硬度分析

本文用前期实验选出的最佳工艺参数及熔覆层数,通过两种铁基合金粉末对45号钢,按同步供料法进行激光熔覆实验;对最佳工艺参数及熔覆层数时的熔覆层的显微硬度进行分析.     

A New Strategy to Effectively Suppress the Initial Capacity Fading of Iron Oxides by Reacting with LiBH4

In this work, a new facile and scalable strategy to effectively suppress the initial capacity fading of iron oxides is demonstrated by reacting with lithium borohydride (LiBH₄) to form a B‐containing nanocomposite. Multielement, multiphase B‐containing iron oxide nanocomposites are successfully prepared by ball‐milling Fe₂O₃ with LiBH₄, followed by a thermochemical reaction at 25–350 °C. The resulting products exhibit a remarkably superior electrochemical performance as anode materials for Li‐ion batteries (LIBs), including a high reversible capacity, good rate capability, and long cycling durability. When cycling is conducted at 100 mA g^?1, the sample prepared from Fe₂O₃–0.2LiBH₄ delivers an initial discharge capacity of 1387 mAh g^?1. After 200 cycles, the reversible capacity remains at 1148 mAh g^?1, which is significantly higher than that of pristine Fe₂O₃ (525 mAh g^?1) and Fe₃O₄ (552 mAh g^?1). At 2000 mA g^?1, a reversible capacity as high as 660 mAh g^?1 is obtained for the B‐containing nanocomposite. The remarkably improved electrochemical lithium storage performance can mainly be attributed to the enhanced surface reactivity, increased Li⁺ ion diffusivity, stabilized solid‐electrolyte interphase (SEI) film, and depressed particle pulverization and fracture, as measured by a series of compositional, structural, and electrochemical techniques.     

Structure‐Properties Relationship in Iron Oxide‐Reduced Graphene Oxide Nanostructures for Li‐Ion Batteries

Non‐aqueous sol‐gel routes involving the reaction of metal oxide precursors in organic solvents (e.g., benzyl alcohol) at moderate temperature and pressure, offer advantages such as high purity, high reproducibility and the ability to control the crystal growth without the need of using additional ligands. In this paper, a study carried out on a series of iron oxide/reduced graphene oxide composites is presented to elucidate a structure‐properties relationship leading to an improved electrochemical performance of such composites. Moreover, it is demonstrated that the easy production of the composites in a variety of temperature and composition ranges, allows a fine control over the final particles size, density and distribution. The materials obtained are remarkable in terms of the particle's size homogeneity and dispersion onto the reduced graphene oxide surface. Moreover, the synthesis method used to obtain the graphene oxide clearly affects the performances of the final composites through the control of the restacking of the reduced graphene oxide sheets. It is shown that a homogeneous and less defective reduced graphene oxide enables good electrochemical performances even at high current densities (over 500 mAh/g delivered at current densities as high as 1600 mA/g). The electrochemical properties of improved samples reach the best compromise between specific capacity, rate capability and cycle stability reported so far.     

珠光体灰口铸铁激光硬化层中石墨相行为研究

利用光学显微镜、电子探针等微观分析手段对灰口铸铁激光硬化层中石墨相行为进行了较为深入的分析。结果表明,石墨在熔化层中完全溶解,且扩散较均匀;相变硬化层中石墨部分溶解,而扩散不均匀;在过渡层中石墨则基本不溶解。由分析可知,石墨的这些行为与硬化层的组织及硬化效果有极其密切的关系。