Corrosion of Silver-Cored Co-20Cr-35Ni-10Mo Composite for Networked Neuroprosthetic System

Abstract

Abstract Corrosion behavior of a silver-cored composite wire with Co-based alloy Co-20Cr-35Ni-10Mo outer tube and a silver core in vitro conditions was investigated. The electrochemical effect of the component materials on the overall corrosion behavior of the composite wire was elucidated. The formation of silver chloride corrosion product on the corroding silver core limited ionic transport therefore restricted further dissolution at the silver metal surface. Galvanic action between a Co-20Cr-35Ni-10Mo cathode and a silver anode was examined. Dissolution rate of the silver core in a composite wire obtained from immersion tests in a physiological solution of 9 g/L NaCl at 37°C was approximately 22 μm/y, i.e., 0.28 μg/y silver dissolved for a 37-μm-diameter silver core. Nearly all of the silver dissolved precipitate as silver chloride, i.e., approximately 0.37 μg/y.