Preparation of ultra fine nickel-copper bimetallic powder for BME-MLCC

The preparation of ultra fine nickel-copper bimetallic powder with two-stage chemical reduction method was investigated. Reductive sugar and hydrazine hydrate were employed as reducing agent in different reductive stage, respectively. Reaction of CuSO₄·5H₂O with reductive sugar at 70 °C gives cuprous oxide and copper particles, then as-prepared mixture and nickelous hydroxide were reduced by hydrazine hydrate, and nickel-copper powder having excellent dispersibility was prepared. Influences of nickel added on composition and dispersibility of powder were studied. TG/DTG/DTA of nickel-copper powder, which is stable in room temperature, were discussed with thermal analyzer. Relation of nickel content to oxidation temperature was investigated. Ni-Cu bimetallic powder particles have a fully coated structure when nickel content is up to 30%. As-prepared nickel-copper powder was applied in base metal electrode-multilayer ceramic capacitor (BME-MLCC). The end termination has high adhesion force, fairly good densification, low resistivity, excellent solderibility behavior and resistance behavior to soldering.     

激光熔覆用钴基合金粉末的研究

对激光熔覆用WFLC－11钴基合金粉末的激光熔覆工艺和熔覆层性能进行了研究，获得了WFLC－11钴基合金粉末激光熔覆层厚度与最小比能量关系曲线和熔覆层的组织、高温硬度等性能数据，为选择和使用WFLC－11钴基合金粉末提供了依据。     

激光焊接超细基胎体金刚石薄壁钻

采用激光焊接超细预合金粉胎体，开发了新的薄壁钻产品，通过对与现有的产品工艺、性能测试以及实际使用分析对比，结果表明：激光焊接与普通钎焊相比结合强度提高2－3倍，克服了胎体脱落问题，胎体耐磨性提高了50％－120％，其中轴向磨损速率提高1．2倍；钻削速度提高30．4％，工矿适应性增加，使用寿命提高25％－108％。     

TiAl基合金粉末爆炸烧结特性常数的测算

本文测算了自蔓延高温合成TiAl基合金粉末的爆炸烧结特性常数值：γ＝1．44，lgβ＝25．25，并为试验证实，这为获取大尺寸TiAl基合金提供了理论依据。     

添加高速钢粉对烧结钢组织与性能的影响

研究了添加高速钢粉对烧结钢组织与性能的影响。实验结果表明，含２０％高速钢的烧结钢综合力学性能最好；添加高速钢粉能导致烧结钢密度减小的冲击韧性降低，当高速钢含量增中时，硬度随之增加，烧结钢中残余奥氏体和马氏体的含量与高速钢的含量呈线性关系。烧结钢中的马氏体显微硬度很高，它主要原高速钢粒子和原铁粒子的连接区域形成。     

粉末冶金压机的应用与进展

简要介绍了当前国内以压制方法生产粉末冶金零件的企业所用压机的基本情况；国内粉末冶金压机生产与开发状况；现代国外知名品牌压机的技术特点与最新发展；分析和总结。     

The magnetic applications choice among ferrite ceramics,metallic strips,or metal powder cores

Iron-based metallic strip materials such as iron, silicon-iron, and amorphous metal are used for low frequency (50–60 Hz. line) power applications. Low-loss Nickel-based alloys as high permeability strip or insulated powder cores are the choices for stable, low-level higher frequency applications. Iron-based powder cores offer low cost as power supply filter chokes. Ceramic ferrites combine highest frequency operation with low cost and reduced component size as transformers and chokes in telecommunication and high frequency power supply applications.     

Three-Dimensional Solution and Experimental Confirmation for the Electric Resistivity Testing of Surface-Breaking Defects in Green-State Powder Metallurgy Compacts

This paper investigates electrostatic voltage distributions around a surface-breaking flaw due to an injected current of known strength. The direct 3-D solution of the voltage behavior over the flawed surface is obtained numerically by the use of a boundary integral formulation. A novel iteration method is applied to solve the resulting electrostatic integral equation for the unknown surface voltage distribution. In addition to investigating the sensitivity of different flaw sizes to the observed surface voltage distribution, important issues such as suitable probe spacing and current flow orientation are studied. For sufficiently small surface-breaking flaws, a simple image source model is developed to evaluate the voltage response of hairline cracks. The model is tested by comparing it with the developed numerical solution. Experiments aimed at establishing the validity of the modeling approach show remarkable agreement with the theoretical model.     

单色光石英退偏器的退偏机理及性能研究

研究了单色光石英退偏器的退偏机理；定义了退偏度作为衡量退偏器性能的物理量。从实验上在４４０～９２０ｎｍ的光谱范围测试了器件的退偏度，结果表明：只要器件的结构角适当，或者适当调节入射光束的截面大小，便可对某一单色线偏振光实现很好的退偏。     

冻融循环下云母石英片岩三轴力学特性与强度预测模型

为探究云母石英片岩物理力学特性受冻融循环作用的影响,对饱水云母石英片岩开展了0、25、50、75、100次冻融循环试验,并对试样分别进行了4级围压下的常规三轴压缩试验,研究了其动弹性参数、三轴压缩破坏形式及三轴抗压强度的变化规律,取得如下成果:①随着冻融循环次数的增加,三轴抗压强度、动弹性模量、动剪切模量及动体积模量呈指数衰减,黏聚力及内摩擦角则呈线性衰减趋势;②随着冻融循环的进行,围压对试样强度的增大作用逐渐削弱,冻融循环对试样强度的劣化作用逐渐凸显;③冻融作用使云母石英片岩三轴压缩破坏形态由张拉破坏逐步演化为顺片理剪切破坏;④基于Jaeger破坏准则建立了一种以冻融循环次数、片理面倾角及围压为控制参数的斜交片理云母石英片岩三轴抗压强度预测模型,预测结果与实测数据具有较好的一致性。研究成果可为研究云母石英片岩冻融损伤劣化规律提供参考。