Molecular Dynamics\nInvestigation of Erosion Behavior\nand Mechanism of TiN Coatings at the Nanoscale: Implications for Wear\nin Oil Fracturing Environment

Due to its high strength and toughness,\nthe TiN coating\nis considered\none of the most promising coatings for resistance to particle impact\nand erosion wear in oil fracturing environments. In this study, based\non the combined potential file of the Fe–Ti–N ternary\nsystem, nanoscale simulation models of TiN/Fe with different crystal\nplanes ((001), (110), (111)) are established for the first time. Molecular\ndynamics simulations (MD) were used to investigate the effects and\nmechanisms of wear resistance and erosion resistance of the TiN coating\nunder nanoscale indentation, scratching, and continuous impact. The\ndifference in the surface properties of TiN coatings with different\ncrystal faces is emphasized. The results indicate that there is no\nabsolute best crystal plane. Due to the differences in molecular gaps\nbetween different crystal planes, surface groups on the lattice interface\nwith the external environment, binding points between molecules within\nthe lattice, types of forces, and modes of action, different crystal\nplanes exhibit different surface properties under different wear forms.\nIn the indentation and scratch stage, TiN(111) has better stability\nand greater hardness due to the structural advantages of its own triangular\nlattice, which can resist external loads, produce less wear debris,\nand basically does not appear with cracks and other surface damage\nexcept scratches. During the impact phase, TiN(001) exhibits greater\nelastic resilience, maintaining surface stability even after continuous\nparticle impact.