Tribo-Induced Phase Transformation and Associated Evolution of Friction of NiCrB Alloy

In the present study, the tribological behavior of NiCrB coating at various loading conditions was investigated. At lower load, evolution of amorphous α-Fe2O3, Fe3O4, and Cr2O3 phases were observed in wear scars, whereas at higher loading conditions the growth of these phases was prominent. Among the different phases formed, the crystalline Cr2O3 phase dominated at higher loading conditions.

Transformation of these phases occurred with a change in loading conditions, which is attributed to the growth and oxidation of oxide scales. The morphology of wear scars was found to change with a change in loading conditions. These changes significantly damaged the oxide scale by cracking and fretting at higher loading conditions.

Evolution of amorphous and crystalline Cr2O3 gives rise to a coefficient of friction value comparable to that of the lubricant phase of α-Fe2O3.