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Excessive solder corrosion in the radiator or heater core can cause engine failure due to overheating as well as destroying the components of the cooling system. Some solders corrode more easily than others. This work investigates how solder composition affects solder corrosion. Corrosion measurements involved two engine coolants and made use of the environment of the glassware test. In the GM-6038M coolant, corrosion of lead-tin solders increased exponentially as the lead content of the solder increased from 60% to 100%. In the ASTM D-3585 coolant, corrosion was constant for solders containing 60% to 90% Pb and corrosion increased exponentially for solders containing over 90% lead. In either coolant, to reduce solder corrosion it is advisable to avoid solders containing 90% or more lead in the repair or manufacture of radiators and heater cores. Two tin-based lead-free solders were examined as well as the more common lead-tin solders.

Adhesive joint durability was compared for the following sheet steels: bare, hot-dip galvanized, electrogalvanized, zinc-nickel electroalloyed, zinc-iron electroalloyed, Zincrometal, Zincroplex/electrogalvanized, Zincroplex/zinc-nickel electroalloyed, and chromium oxide electrogalvanized. Experiments monitored lap-shear joint strength with exposure to a corrosive environment. Results show durability depends on the corrosion resistance of the steel sheet. Durability was generally greater with coated steel sheet and particularly with chromium oxide electrogalvanized steels.

Lap-shear strength degradation of epoxy bonded coated steels was studied with exposure to cyclic salt-spray and thermal environments. Joint strength degradation with cyclic salt-spray and humidity exposure is slow with coated steel adhereneds, e.g, hot-dip galvanized, electrogalvanized, galvannealed, and Zincrometal®, and fast with bare steel adherends. Corrosion and dissolution of the steel coating, not adhesive degradation, is the primary mechanism leading to the loss of joint strength in this environment. With unexposed samples, joint strength is limited by either the mechanical strength of the sheet or the adhesion of the coating. The mill and drawing oils used had little effect on initial adhesive joint strength.