Micro-abrasion–corrosion interactions of Ni–Cr/WC based coatings: Approaches to construction of tribo-corrosion maps for the abrasion–corrosion synergism

The process of micro-abrasion–corrosion has been the subject of much research in recent years due to the fact that the action of micron sized particles, typically less than 10 μm in diameter, can cause significant degradation of materials in many diverse environments involving aqueous corrosion. Cermet based coatings are often used to combat micro-abrasion–corrosion, but there has been little work carried out to characterize the performance of such coatings exposed to micro-abrasion–corrosion or to provide a basis for coating optimisation. In addition, a basis for defining the various micro-abrasion–corrosion interactions has not been suggested to date.In this study, the micro-abrasion–corrosion performance of a Ni–Cr/WC coating was assessed and compared to the performance of the steel substrate. The results were used to identify regimes of micro-abrasive wear as a function of applied load and pH of the solution. In addition, micro-abrasion–corrosion maps were constructed based on the results, showing the variation between micro-abrasion–corrosion regimes, as a function of applied load and pH of the solution.

► Effects of pH and applied load on the micro-abrasion–corrosion of Ni–Cr/WC coatings. ► Potentiodynamic polarization behavior for the coating at various loads and pHs. ► Separation of corrosion and micro-abrasion contributions in the mass change recorded. ► Establishment of the synergy between micro-abrasion and corrosion for exposure of the coating in the test conditions. ► Metallurgical evaluation of the Ni–Cr matrix degradation and WC particle removal following exposure to micro-abrasion conditions. ► Proposal of novel micro-abrasion–corrosion maps for Ni–Cr/WC coatings as a function of pH and load.