Preparation And Properties Of Electroless Silver Plated Aramid

Aramid fabric has the excellent characteristics of light weight,high strength,corrosion resistance and high temperature resistance,and has a broad application space in many fields of national production and life.Metallized aramid fiber can obtain conductive fabric with excellent comprehensive performance.However,the surface of aramid fiber is smooth and chemically inert,and it is difficult to combine with other materials.It is impossible to obtain a continuous and stable metal layer on its surface by methods such as physical sputtering or electroless deposition.The surface of aramid fiber is modified to improve its reaction.Reactivity is the key to obtain high-performance conductive aramid fabrics.Usually,the electroless silver plating process of aramid fiber involves strong acid or strong alkali etching fiber and SnCl₂-PbCl₂ sensitization-activation treatment.There are problems such as easy damage to fiber body by etching method,expensive palladium catalyst reagent and biological toxicity.Modified pretreatment methods and palladium-free electroless plating have become the main research directions in the field of aramid fiber electroless silver plating.In addition,as a high-performance conductive fiber,silver-coated aramid fiber has also become a research hotspot in this field in recent years.This paper studies the pretreatment and electroless silver plating technology of aramid fabrics,and explores the best way to etch aramid fabrics with acid,alkali and salt alone or in combination.Dopamine is used to polymerize and modify the fiber surface,and it is optimized by palladium-free electroless silver plating.,the silver-plated aramid fabric with excellent electrical conductivity was prepared,and its application properties such as electric heating were explored.The specific research contents are as follows:(1)Research on the surface etching and modification process of aramid fabric.The aramid fabrics were etched with aqueous solutions of HCl,KOH,CaCl₂ and KCl alone or in combination.Etching effect of aramid fabric treated with single etching solution,HCl+CaCl₂and KOH+KCl compound solution;self-polymerization of dopamine(DA)under alkaline conditions,deposition of polydopamine(PDA)on the fiber surface after etching Modified fibers and introduced phenolic hydroxyl groups on the surface to analyze the effect of dopamine modification on the surface morphology and chemical structure of aramid fibers.The results show that the compound solution of HCl+CaCl₂ and KOH+KCl can improve the surface roughness of the fiber and form more polar groups,thereby enhancing the etching effect of the aramid fabric,which is beneficial to the formation of a uniform PDA polymer film on the fiber surface..(2)Discussion on the methods and conditions of palladium-free electroless silver plating on the surface of PDA-modified aramid fabrics.The effects of KOH and KCl concentration,DA concentration,AgNO₃ concentration,C₆H₁₂O₆ concentration,activation method,electroless plating temperature and electroless plating time on the electrical conductivity of silver-plated aramid fiber were discussed.The surface of PDA modified aramid fabric was determined by single factor and orthogonal experiments.The best process of electroless silver plating without palladium,the resistance of silver-plated aramid fabric is 0.5542?0.0514?/sq.(3)Study on the electrical conductivity and electrothermal application properties of silver-plated aramid fabrics.The stability of electrical conductivity of silver-plated aramid fabrics in high and low temperature environments,ice and flame environments,and acid-base and organic environments was tested,and the electrothermal properties,long-term stability and reusability of silver-plated aramid fabrics with different resistances were explored..The research shows that under the applied voltage of 1.0 V,the electric heating sheet made of silver-plated aramid fabric can heat up from 20?to 84.4?within 25 s;under the applied voltage of 0.6 V,it can work continuously for 10000 s and repeatedly heat up for 50 times.,the equilibrium temperature is always maintained at about 62?.