Corrosion Assessment for Additive Manufactured Alloys Based On Interfacial Active/ Passive Mechanisms

Abstract

Passivity as an electrochemical/chemical mechanism has an important impact on engineering materials; the process helps to mitigate and control the corrosion process by providing a nano- to Angstrom- scale protective barrier layer on a metallic surface. The protectiveness offered by this natural surface mechanisms could influence the original mechanical properties designed for classical and additive manufactured alloys. In this work, comprehensive experimental designs are implemented by combining tribocorrosion, electrochemical testing, high-resolution characterization, and additive manufacturing processes that demonstrate the correlation of metallography structure to the corrosion and passivity behavior of two different alloys, Titanium (Ti6Al4) and Aluminum –Silica (AlSi12). These two different alloys systems (classical manufactured and 3D printing additive manufactured) are characterized by electrochemical interfacial mechanisms when exposed to corrosive environments and result in different passive/active states. Titanium cast parts resulted in better passivation efficiency than the additive alloy while the additive alloy preserved an oxide layer that is more robust against corrosive ions. In aluminum alloy systems, additive manufactured alloy demonstrated more stable and homogeneous properties with higher passivation efficiency and protective passive layer.