Corrosion Resistant Aluminium Radiator Materials for Vacuum and Controlled Atmosphere Brazing

In the present work a so called long-life tube material (designated 3005LL) has been compared to standard AA3003 and AA3005 tube materials regarding post-braze strength and corrosion resistance. Furthermore the corrosion resistance of vacuum and controlled atmosphere brazed radiators have been evaluated. The effect of different tube and fin combinations on the corrosion properties has been investigated using 3005LL, AA3003 and AA3005 tube cores and AA3003, AA3003 + Zn and AA6063 fins.

The results show a considerable increase in post-braze strength and corrosion resistance for 3005LL compared to the standard tube materials. Vacuum brazed radiators with 3005LL tubes have a significantly longer time to perforation than radiators with standard tubes. AA6063 fins in combination with 3005LL tubes proved to perform better than AA3003 fins due to a more beneficial electrochemical potential relation between tube and fin. The controlled atmosphere brazed radiators show a better corrosion resistance than vacuum brazed radiators and the effect of the 3005LL tube is less pronounced. The 3005LL tube in combination with AA3003 fins performs reasonably well but an addition of 0.5-1.0% Zn to the fin material would further improve the corrosion properties.