EFFECT OF ALLOYING ELEMENT ON THE WETTABILITY AND CORROSION RESISTANCE OF LOW-TIN SOLDERS

The automotive and tractor radiators were brazed mainly with solders containing less than 10% Sn and 0.5-1.5% Ag in the last 15 years abroad,primarily to save cost and to improve mechanical properties.Solders with less than 5% Sn,besides low wettability,showed some problems in corrosion resistance after long service.Adding Zn,REs,Ag,Sb and Bi alloys to Pb-3% Sn and Pb-10% Sn solder systems can obviously improve their corrosion resistance to water coolant.Wet test for these high lead solders demonstrated that Zn,REs and Ag can significantly increase wettability on copper within the range tested.But Sb and Bi can decrease the wetting properties of solders.