| Abstract: | Electrochemical and weight loss measurements have been used to study galvanic corrosion of three-metal couples extending earlier studies of the galvanic interaction of two dissimilar metals. Materials studied include Zn, Cd, Cu, Ni, the Al alloys 2024, 6061 and 7075, 4130 steel, stainless steel 304, Ti-6Al-4V, Inconel 718 and Haynes 188 in 3.5% NaCl at 21°C. Different electrical arrangements for galvanic current measurements using the zero resistance ammeters (ZRA) are discussed. With the use of two ZRA's the current flowing on each of three metals can be continuously monitored. Weight loss data are used to obtain additional information concerning accelerated corrosion or protection of the individual metals in galvanic couples. Such measurements can be used to evaluate the corrosion behavior of metal combinations such as encountered in a porous Cd coating on a steel fastener installed on an Al structure. |
