空心微珠热碱液活化化学镀银

Electroless silver plating activated with thermo-alkaline solution on fly ash cenosphere surface

将空心微珠在HF和NaF的缓冲液中进行粗化处理,然后用75℃热碱液活化,再以甲醛为还原剂,在空心微珠表面化学镀银。通过扫描电镜(SEM),X射线能量色散谱仪(EDS)和X射线衍射(XRD)对所得复合粉体的表面形貌、成分以及镀层与空心微珠的结合强度进行研究与分析,并探讨pH值对沉积效果的影响。结果表明:粗化处理可增大空心微珠的表面粗糙度,从而提高Ag+的形核能力,所得镀层完整、致密。镀液pH升高,包裹层更完整、致密,且银层增厚。在pH=12.9的条件下,可实现银层对空心微珠均匀、致密的包裹,得到镀层结合强度较高、银层较厚、银晶粒尺寸为23.3nm的银包空心微珠复合粉体。

Electroless silver planting on the surface of fly ash cenospheres using formaldehyde as reducing reagent was prepared by adopting a buffer solution of HF and NaF to rouging treatments and then thermo-alkaline treatment at 80 ℃ for instead of palladium activating treatment. The morphologies of the prepared composite particles were studied with SEM and their chemical composition were confirmed by EDS and XRD. The results revealed that,the coatings of fly ash cenosphere particles are uniform and dense,which is due to the silver nucleation effect improving by surface roughness. Surface roughing treatments could increase surface roughness of the cenosphere particles. With the pH value of plating solution improving,the coatings become more and more uniform and dense,moreover the silver layer is obviously thickened. The uniform and dense silver coating for the silver-coated fly ash cenospheres composite powders with thick silver layers,high bonding strength and the silver particles of 23.3 nm are prepared when the pH value is 12.9.