Cyclic polarization measurements are typically used to characterize metals and alloys that derive their corrosion resistance from the formation of a thin passive film. Alloys such as 316LVM and MP35N, often used in implantable medical devices, derive their corrosion resistance from passivity. These alloys can be susceptible to localized corrosion due to breakdown of their passive films. Cyclic polarization measurements done in accordance with ASTM F2129* are used at EIC Biomedical to assess corrosion resistance of these and related alloys. Cyclic polarization measurements are also useful for characterizing noble metal electrodes such as platinum and gold, and in particular for assessing the likely severity of galvanic corrosion between noble and non-noble metals in implantable devices.

		  		These measurements are usually made in Ringer’s solution at  37oC using a 5%CO2/95%N2  		gas sparge to control  pH. A gas sparge of 5%CO2/6%O2/89%N2 is used  when investigating   		the influence of dissolved oxygen gas.    

Platinum
	Potentiodynamic cyclic polarization of a platinum electrode in Ringers solution at pH 7.4 and 37oC. The Ringers was purged with 5%CO2/95%N2 to maintain pH and remove dissolve oxygen gas.
Gold
	Potentiodynamic cyclic polarization of a gold electrode in Ringers solution at pH 7.4 and 37oC. The Ringers was purged with 5%CO2/95%N2 to maintain pH and remove dissolve oxygen gas.

				*See  ASTM International standard ASTM 2129-08 “Standard Test Method for Conducting Cyclic  Potentiodynamic   				Polarization Measurements to Determine the Corrosion  Susceptibility of Small Implant Devices.”  www.astm.org