Studies on Preparation and Properties of Silver Coated Nickel Powder

研究了电磁屏蔽用银包镍粉的制备技术，得到了综合性能优异的银包镍粉。采用扫描电镜(SEM)分析了银包镍粉的形貌，结果表明随着粉体银含量(质量分数(wt%))的增加，银镀层的均匀性和致密性得到改善，在50%银含量情况下，银包镍粉表面光滑，包覆均匀。X射线衍射分析(XRD)表明，镍粉表面获得的Ni、Ag相均为立方晶体，没有氧化物的存在，说明银包镍粉比较致密，镀层比较均匀。综合SEM及XRD分析，银包镍复合粉体实际上是以Ni为核心，Ag为外壳构成的核壳结构。热重分析(TGA)表明，镍粉经过镀银后，粉体的起始氧化温度有较大幅度提升，大约提高60℃左右，高温抗氧化性能也得到改善。 Preparation of silver coated nickel powder for electromagnetic shield has been studied and the silver coated nickel powder with the best properties has been obtained. Surface morphology of the silver coated nickel powder was analyzed by SEM, and result shows that with increasing the content of silver (mass fraction (wt%)) in the coatings, the silver coated nickel powder was coated completely. X-ray diffraction shows the nickel and silver in the surface of nickel powder is cubic crystal, and there are no any oxides in the silver coated nickel powder. This shows that the silver coated nickel powder is dense, uniform coating. Combine SEM with XRD displays the silver coated nickel powder is in the form of nickel being core and silver being outer layer. Thermo gravimetric analysis showed that after the nickel powder was plated with silver, the initial oxidation temper-ature of the powders increased greatly, and the high temperature oxidation resistance has also been improved.