镀银粉煤灰制备及其在柔性导电膜中的应用

Preparation of Silver-plated Fly Ash and Its Application in Flexible Conductive Film

目的在粉煤灰表面镀银,以优化粉煤灰在柔性基体中的润湿性,提高其与柔性基体之间的界面结合力。方法首先对粉煤灰进行高温碱洗、粗化、敏化和活化预处理,随后进行化学镀银,通过研究镀液中硝酸银、氨水和甲醛用量等工艺参数,获得导电性能优异且镀层致密、均匀的镀银粉煤灰(简称Ag/FA)粉末。最后将导电性最佳的Ag/FA粉末作为中间填料,以液体硅橡胶为柔性基体,二甲苯为溶剂,制备三明治结构柔性导电膜。采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X-射线衍射仪(XRD)以及电阻率测试仪等设备,对不同影响因素下Ag/FA粉末与柔性导电膜的微观形貌、组成和导电性进行表征。结果研究结果显示,粉煤灰镀银最佳配方为:硝酸银10 g/L,氨水40 mL/L,甲醛40 mL/L,温度30℃,时间30 min。该工艺条件下,Ag/FA粉末的体积电阻率可达4.68×10^(-4)Ω·cm。当Ag/FA粉末在柔性硅胶膜中的质量分数为7.69%时,即可形成完整的导电通路;继续增加至25%时,三明治结构柔性导电膜的导电性优异,体积电阻率可达2.65×10^(-3)Ω·cm,可反复折叠、弯曲和拉伸。结论采用简单的化学镀银工艺可使粉煤灰表面导电功能化,改善其与柔性聚合物材料之间的结合力,开拓功能化粉煤灰在电磁屏蔽和柔性电子材料领域的应用。

This work aims to prepare conductive silver coated fly ash by electroless plating method,which the surface wettability of fly ash would be improved and further enhance the interfacial binding force between fly ash and flexible matrix.Hence,a novel approach to prepare high performance conductive polymer materials has been provided.Firstly,fly ash particles were pretreated by alkaline wash,coarsening,sensitization and activation.Then,electroless silver plating was carried out on the surface of fly ash particles.By studying the technological parameters such as the amount of silver nitrate,ammonia and formaldehyde in the plating solution,the silver coated fly ash(for short Ag/FA)powder was successfully obtained,which possessed both excellent conductivity and dense and uniform coating.Finally,sandwich structure flexible conductive film has been prepared,which Ag/FA composites were used as the intermediate conductive filler,and liquid silicone rubber was used as the flexible matrix.Herein xylene was chosen as the solvent to dilute liquid silicone rubber.The microstructure,composition and conductivity of Ag/FA composites under different influencing factors and flexible conductive film were characterized by scanning electron microscope(SEM),transmission electron microscope(TEM),X-ray diffractometer(XRD)and resistivity tester.The research results show the optimal amount of silver nitrate,ammonia water and formaldehyde are 10 g/L,40 mL/L,and 40 mL/L,respectively.The plating temperature is 30℃,and plating time is 30 min.At this process condition,the volume resistivity of Ag/FA composites could reach 4.68×10^(‒4)Ω·cm.When the mass fraction of Ag/FA composites in flexible silicone membrane was 7.69%,a complete conductive path has been formed perfectly.When added to 25wt.%,the sandwich structure flexible conductive film exhibited excellent conductivity of 2.65×10^(‒3)Ω·cm,both could be folded,bended and stretched repeatedly.The surface of fly ash powders could conductively by a simple electroless silver plating method.And the binding force between fly ash and flexible polymer material has been improved,so as to expand the application field of functionalized fly ash in electromagnetic shielding and flexible electronics materials.