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

Abstract

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.

KEY WORDS:

• NiCrB
• Oxide Scales
• Phases
• Friction
• Wear

ACKNOWLEDGEMENTS

The authors thank Ashok Bahuguna, SND/Indira Gandhi Centre for Atomic Research (IGCAR), for dimensional measurements of wear tracks using surface profilometry. The authors are also grateful to Dr. C. S. Sundar, Director, Material Science Group, IGCAR, for providing continuous encouragement and support.

Review led by Dong Zhu