Molecular Dynamics Investigation of Protective Mechanisms and Wear Resistance of TiN/Ti Multilayer Coatings in Oil and Gas Applications.

TiN/Ti multilayer coatings exhibit exceptional erosion resistance under sand-laden high-speed flow impact, making them promising protective coatings for critical components in oil- and gas-extraction. However, existing studies of TiN/Ti multilayer coatings have been predominantly experimental and have focused on structural design and process parameter optimization. Consequently, the atomic-scale mechanisms remain unclear, limiting further improvements in the service life of these coatings. To reveal the protective mechanisms of TiN/Ti multilayer coatings at the atomic scale, this study establishes molecular dynamics models of TiN/Fe and TiN/Ti/Fe and systematically compares their microscopic responses under indentation, scratching, and impact loading. The results show that the TiN/Ti multilayer coating effectively dissipates energy through the plastic deformation of the Ti layer, reconfigures the energy distribution and transfer pathways within the workpiece, and confines deformation and damage within the TiN/Ti coating, thereby protecting the Fe substrate. These findings provide an atomistic basis for the design of erosion-resistant multilayered coatings.