Pure silver surface layer on the oxidized Ag-Sn-In material

One of the drawbacks of internally oxidized Ag-Sn-Al alloy is that a pure silver layer always appears on the oxidized material surface after oxidation. Although the thickness of the pure silver layer varies only between 0.0002 and 0.001 in. (0.005 to 0.025 mm), the silver layer always causes light tack welding in the early stage of a switching operation. The severity depends on the device´s mechanical design as well as the electric current. The surfaces of several Ag alloys were examined under an optical microscope and cross sections were then taken and investigated by the standard metallography method. It is found that one pure silver surface of the Ag-Sn-In material can be eliminated by oxidizing the material from one side.<>