Molybdenum foil surface silver plating
Molybdenum and molybdenum alloy metal high temperature resistant materials, can maintain high strength at high temperatures, but also has high thermal conductivity and low thermal expansion coefficient, good heat shock performance, electrical conductivity and wear resistance, is widely used in the field of aerospace, including molybdenum foil for spacecraft solar cell array interconnecting. However, the weldability of molybdenum is relatively poor, and it will be strongly oxidized at high temperature, and this oxide film has no protective effect, so it is necessary to modify the surface of molybdenum by electroplating. Because silver has good brazing properties, silver is usually plated on the surface of molybdenum to improve weldability and reduce or prevent oxidation of molybdenum. However, because there is often a natural oxide (MoO3) on the surface of molybdenum, it will interfere with the adsorption of the coating, and it is difficult to form an alloy (solid solution) between molybdenum and silver, so it is difficult to electroplate silver on the surface of molybdenum, direct silver plating often does not adhere well, and the quality of the coating is poor. The solution to the difficulties of molybdenum plating is generally to use pre-plating or impact plating on the surface of a thin layer of metal (such as chromium, nickel, gold, rhodium, platinum, etc.), after high temperature heat treatment and then continue plating, the process is more cumbersome. At the same time, pre-plated nickel has an adverse effect on electrical conductivity, while gold, rhodium, and platinum will also increase the cost.
The Ag modified layer without obvious interface and with high bonding strength can be obtained by direct implantation of Ag ions into molybdenum by metal plasma injection modification technology. The natural oxides can be removed by ion beam bombardment to improve the conductivity of the surface, and then the Ag electrocoating obtained by molybdenum plating has good quality and high bonding strength.
