Sacrificial Cathodic Protection of Mg Alloy AZ31B by an Mg-5Sn Surface Alloy

摘要

A solid solution Mg-5Sn alloy is evaluated as a sacrificial anode for the cathodic protection of AZ31B. Uncoupled Mg-5Sn is shown to have superior barrier properties and reduced cathodic kinetics relative to AZ31B. The performance as a sacrificial anode was studied in situ with global and local measurements of galvanic coupling between the Mg-5Sn alloy and AZ31B when immersed in 0.6-M aqueous NaCl solution. The scanning vibrating electrode technique (SVET) was utilized to map the local current density distributions across the interface of the galvanic couple. Undesirable polarity reversal was observed during the initial 10 h of immersion, after which protection was offered. A self-corrosion rate of 52% was observed.