Oerlikon Copperfil CuSi3 description: COPPERFIL CuSi3 is used for welding of copper base alloys, for example, copper-silicon, copper-zinc and galvanized sheets, also welded to steel. This wire is frequently used for joining in artistic foundries, for welding galvanized sheets and even as a steel cladding. It is also suitable for surfaces subject to corrosion. COPPERFIL CuSi3 is used also for GMA Brazing where a very small active component is suggested in the shielding gas.