Interfacial reaction and growth behavior of reaction layer of Si_3N_4/Si_3N_4 joint brazed by Cu-Zn-Ti filler alloy

Si3N4 ceramic was jointed to itself using a filler alloy of Cu-Zn-Ti by the reaction between Ti and Si3N4. The microstructure of the interface in the joint is found to be Si3N4 ceramic/TiN reaction layer/Ti5Si3 reaction layer. The grain size of the TiN and Ti5Si3 reaction layer is 0.1μm and 1-2μm, respectively. There is no crystal orientation relationship between TiN reaction layer and Si3N4 ceramic or Ti5Si3 reaction layer. The kinetic equation for calculating the thickness of the reaction layer was obtained. When a （CuZn）85Ti15 alloy is used as the filler alloy, the apparent activation energy of the growth of the reaction layer is 201.69kJ/mol.

Particle shape effects on ductility of SiC particle reinforced LD2 matrix composites investigated by AFM-based nanoindentation

An AFM (Atomic Force Microscope) based nanoindentation method for local measurement of mechanical properties near interfaces in both angular and blunted SiC particle reinforced LD2 composites is presented. The blunted composite exhibits an improved ductility than the angular counterpart. The nanoindentation examination shows that the micromechanical properties near interfaces distribute unevenly and vary with particle shape in the SiC p/LD2 composites. There are a higher nanohardness value and a lower plastic deformation capacity around an angular particle than around a blunted one. It is inferred that the residual stress and strain concentrations are severer around the angular particle, which causes matrix cracking at a lower external strain level and leads to a lower ductility of the angular composite.

滚动轴承和滚珠丝扛中润滑油脂的外溅性

滚动轴承或直线运动轴承中的润滑油脂，可能飞溅出颗粒，粘附在液晶制品或硬盘上，导致设备失效。所以，这种设备轴承所使用的润滑油脂尽可能降低飞溅性。但低飞溅性的润滑油脂可能带来耐磨性、噪声、阻力矩等问题。因此，我们需要一种油脂，它既具有低飞溅性，又有较高的性能和使用寿命。为了开发低飞溅性的油脂，作者研究了油脂成分和飞溅性的关系。一些数据下面会提到。飞溅颗粒的多少和基油成分有很大关系，例如，润滑油脂基油是矿物油或合成碳化氢油，它们极性低，飞溅颗粒少；相反，如果是酯油，它的极性高，飞溅性也高。飞溅颗粒的多少也取决于增稠剂的类型和含量，例如浓的润滑油脂的飞溅数量少。作者证实了飞溅出来的颗粒不仅有基油颗粒，而且有细小的油脂颗粒，油脂颗粒的直径范围在０．１１ 到０．２μｍ 。