Preparation And Properties Of Silver-Based Amorphous/Nanocrystalline Coatings

Silver,as an ancient precious metal,was discovered and utilized by human beings as early as BC.Among all metals,it has the best conductivity,thermal conductivity and reflectivity,and its ductility is second only to gold,and it also has excellent weldability and corrosion resistance.Silver used to be the most important currency in history,and then was mainly used in modern industry and life.At present,the main applications of silver include photosensitive materials,contact materials,composite materials,silver alloy solders,silver paste,energy industry,catalysts,medicine,antimicrobial materials and so on.However,silver and silver-plated products are exposed to urban industrial atmosphere or sulphur-containing environment.The surface of silver is easily discolored by corrosion.The discoloration of silver surface seriously affects the beauty and use effect of silver products.The topic of this paper comes from the problems in the actual production and collection of silver and silver products.At present,material scientists have analyzed the silver discoloration phenomenon from different aspects,and found some suitable anti-discoloration methods,and achieved some results.With the development of surface treatment and coating technology,it is possible to improve the anti-corrosion and anti-tarnishing ability of silver more effectively.In the experimental part of this paper,nano-silver coatings with different particle size and binary alloy coatings with different composition were prepared by magnetron sputtering.By means of XRD,scanning energy spectrum,TEM,step gauge thickness measurement,XPS,immersion accelerated corrosion,electrochemical corrosion and other characterization and testing methods,the relationship between "process parameters-deposition rate-grain size-corrosion resistance”in single target sputtering was discussed.The Ag-Cr system with the best anti-tarnishing ability of silver in dual target sputtering binary alloy was found,and the effect of composition in the system on the structure of the alloy was explored.What's more,the critical point of amorphous/nanocrystalline and completely amorphous was found as Ag43Cr57.The composition and depth distribution of the oxide film of each coating were analyzed.According to the electrochemical behavior of each sample in different corrosive environments containing S or Cl and combining the glossiness,the Ag60Cr40 alloy coating was selected with the best S corrosion resistance,and the nano-silver coating with the best Cl corrosion resistance.Combining the above two laws,Ag60Cr40 alloy coating is the best choice to resist silver discoloration in a complex environment.These conclusions can provides a new way to solve and improve the problem of silver discoloration.