The Estimation of Localized Corrosion Behavior of Ni-Based Dental Alloys Using Electrochemical Techniques

摘要

The aim of this study is to investigate the electrochemical behavior of the five non-precious Ni-based dental casting alloys in acidified artificial saliva. For comparison, nickel was also investigated. In order to study the localized corrosion resistance, the cyclic potentiodynamic polarization (CCP) and electrochemical impedance spectroscopy were performed. Scanning electron microscopy (SEM) observations were made after the CCP tests. The Ni-Cr alloys with chromium (14-18%) contents were susceptible to localized corrosion. The Ni-Cr-Mo alloy with contents of chromium (≈13%) and molybdenum (9%) presents a dangerous breakdown, but have a zero corrosion potential so that the difference between them is around 650 mV. The Ni-Cr-Mo alloys with higher chromium (22-25%) and molybdenum (9-11%) contents had a much larger passive range in the polarization curve and were immune to pitting corrosion. Pitting resistance equivalent (PRE) of about ≈54 could provide the Ni-based alloy with a good pitting corrosion resistance.