DISSOLUTION OF HIGH-PURITY LEAD AND SUBSEQUENT CRYSTAL-GROWTH DURING THE PREPARATION OF CORROSION COUPONS

High-purity lead discs were prepared using several combinations of pol ishing, rinsing and ultrasonic treatment. Physical degradation of the lead surface and the premature generation and deposition of oxides on the surface were observed for certain combinations of preparation step s. Ultrasonic treatment of the discs was found to be particularly detr imental as it induced significant crystal growth and, in several insta nces, deterioration of the polished surface. Simple air drying of fres hly rinsed discs also led to oxide formation on the surface after as s hort a time as 1 min. An effective method for preparing discs from hig h-purity lead is described.