微波加热合成SiC纳米线的研究

采用单质Si粉和酚醛树脂为原料、均混、成型、碳化, 并以10℃/min的升温速率在1300～1400℃/0.5～2h的微波加热条件下制备了SiC纳米线. 用SEM和TEM观察所得SiC纳米线形貌, EDX检测样品成分. 结果发现: 所制备的SiC纳米线具有典型的SiC/SiO₂芯－壳式缆状结构特征, 直径约为20～100nm. 分析认为, 在微波加热条件下, 液态Si在SiC纳米线生长过程中起着至关重要的作用, 既具有催化作用, 同时又是制备SiC纳米线的关键原料.     

稀土Er对Sn-3.0Ag-0.5Cu无铅焊料合金组织与性能的影响

研究稀土Er含量对Sn-3．0Ag-0．5Cu无铅焊料合金显微组织以及性能的影响。结果表明：当Er含量为0．05％～0．50％（质量分数）时，对该无铅焊料合金的导电性和腐蚀性影响不大，但使熔化区间温度降低：当Er含量为0．05％时，焊点剪切强度最高；当Er含量为0．10％时，焊料铺展面积最大，焊料润湿性有所改善，同时焊料的拉伸强度达到最高；当Er含量为0．25％时，伸长率最大。随着Er含量的增加，该焊料合金的组织由树枝晶向等轴晶转变，且组织逐渐细化。Er的较佳添加量为0．05％～0．25％。     

Effect of adding Ce on interfacial reactions between Sn-3.0Ag-0.5Cu solder and Cu substrate

The formation and the growth of Cu-Sn intermetallic compound （IMC） layer at the interface between Sn-3.0Ag-0.5Cu-xCe solder and Cu substrate during soldering and aging were studied. The results show that Cu6Sn5 IMC is observed at the interface between solder and Cu substrate in all conditions. After aging for 120 h,the Cu3Sn IMC is then obtained. With increasing aging time,the scalloped Cu6Sn5 structure changes to a plate structure. The Cu3Sn film always forms with a relatively planar interface. By adding a small amount of the rare earth element Ce （only 0.1%,mass fraction） into the Sn-3.0Ag-0.5Cu solder alloy,the growth rate of the Cu-Sn IMC at the interface of solder alloy system is decreased. When the time exponent is approximately 0.5,the growth of the IMC layer is mainly controlled by a diffusion over the studied time range.