热处理对空心玻璃微珠表面镀镍层及其吸波性能的影响*

空心玻璃微珠表面镀覆金属合金层(如铁、镍、钴)能大大改善其电磁损耗性能。采用钯活化和化学镀镍工艺制备了空心玻璃微珠表面镀镍层,并对其进行了450℃热处理。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)及其附带能谱仪(EDS)对镀镍和热处理过程中的空心玻璃微珠镀层结构、表面形貌和成分进行分析,采用矢量网络分析仪对镀镍及热处理空心玻璃微珠的吸波性能进行研究。结果表明:采用化学镀技术在空心玻璃微珠表面包覆了一层均匀致密的镍镀层,镍含量高于95.48%,其晶体结构为面心立方,镀层结合力良好;经450℃热处理后,镀层粗糙度变大,增强了Ni-P镀层的晶化,并使晶粒长大,降低镀镍空心玻璃微珠的反射率,在15GHz处,450℃热处理的镀镍微珠反射率最低为-3.8dB,与热处理前相比,反射率降低差值为1.1dB。

Effects of Heat Treatment on Nickel Coatings of Hollow Glass Beads and Its Absorbing

The electromagnetic loss of hollow glass beads(GBs) is improved when metals such as Fe,Ni or Co are coated onto the surface of GBs.Nickel coating was prepared on the surface of GBs using the electroless plating,and the coating was heat treated at 450℃.The structural characteristics,morphology and electromagnetic properties of GBs were obtained by X-ray diffraction(XRD),scanning electron microscope(SEM),and energy dispersive spectrometer(EDS) and the reflectivity were detected by vector network analyzer.Results show that a uniform Ni coating with face-centered cubic structure is coated on GBs by electroless plating,the nickel element of the coating is higher than 95.48%(mass fraction),and the surface roughness and adhesion of the coating is greater by heat treating.Heat treatment at 450 ℃ crystallizes the Ni-coating,which is beneficial for improving electromagnetism of the products.The reflectivity of Ni plated GBs with heat treatment is reduced to the lowest-3.8 dB at 15 GHz,and the D-value is 1.1 dB compared with that of before heat treatment.