Study on cyanide-free silver electroplating of molybdenum foil for spacecraft solar cell array
Molybdenum and molybdenum alloy metal high temperature resistant material, can maintain high strength at high temperature, but also has high thermal conductivity and low coefficient of thermal expansion, good impact resistance and electrical conductivity and wear resistance, is widely used in the field of aerospace, including for spacecraft solar cell array interlinked molybdenum foil. However, the weldability of molybdenum is relatively poor, and it will oxidize strongly at high temperature. This oxide film has no protective effect, so it needs to be modified by electroplating on the surface of molybdenum. Because silver has good brazing properties, it is common to electroplate silver on the surface of molybdenum to improve weldability and to reduce or prevent oxidation of molybdenum. However, there are often natural oxides on the surface of molybdenum, which will interfere with the adsorption of the coating, and it is difficult to form an alloy (solid solution) between molybdenum and silver. Therefore, it is difficult to electroplate silver on the surface of molybdenum, and direct silver plating often does not adhere well, and the coating quality is poor. The solution to the difficulties of molybdenum plating is generally to use preplating or impact plating on the surface of a thin layer of metal (such as chromium, nickel, gold, platinum, etc.), after high temperature heat treatment and then continue plating, the process is relatively tedious.
If the metal plasma implantation technique is used to directly inject Ag ions into molybdenum, the Ag modified layer with no obvious interface and high bonding strength can be obtained, and the natural oxides can be removed by ion beam bombardment to improve the surface conductivity. On the basis of molybdenum electroplating, Ag electrocoating with good quality and high bonding strength can be obtained. A certain amount of Ag ion was injected into molybdenum foil, and after annealing at high temperature, silver was electroplated on the surface of molybdenum foil by cyanide-free electroplating technology. The results were compared with those obtained by cyanide-free electroplating on pure molybdenum foil.
