Applying bipolar electrochemistry to assess the corrosion mechanism of HVOF WC-based coatings with varies binders in different environments

Abstract

Traditional corrosion tests typically only focus on the conditions under which corrosion occurs in hard-facing materials without considering the corrosion rate. However, corrosion growth kinetics is also essential to understanding corrosion performance. This study aims to investigate both the initiation and propagation of corrosion in high-velocity oxygen fuel (HVOF) sprayed WC-based coatings with different binders (Co, Ni, CoCr, and NiCrMo) in 0.1 M HCl, NaCl, and NaOH solutions. To better understand the corrosion mechanism, a novel corrosion test method - bipolar electrochemistry is utilized. This test involves applying a linear potential to the bipolar electrode (BPE), allowing for the estimation of the critical corrosion potential and corrosion growth kinetics for a single sample under a wide range of applied potentials. By comprehending the critical corrosion potential and growth kinetics of HVOF WC-based coatings in various pH solutions, this study provides practical recommendations for choosing suitable binders for different working environments.