Surface feature of the substrate via key factor on adhesion of Cr/Cr₂N multilayer and alloy substrate

This study investigates the relationship between the surface characteristics of substrates and the performance of Cr/Cr₂N multilayer coatings. The microstructure, mechanical properties, and adhesion of the coatings were investigated using SEM, HRTEM, XRD, hardness testing, indentation testing, and scratch testing. Despite exhibiting comparable hardness and fracture toughness, the adhesion of the coating decreases significantly with the elevation of substrate roughness due to the inheritance of surface undulations. Notably, even though the roughness achieved through plasma nitriding substrate exceeds that of grinding substrate, the plasma-nitrided surface maintains a coherent interface with the coating while effectively refining the grain size of the coating. This ultimately leads to an increase in the coating adhesion on the nitrided substrate by over 50 %. The bearing capacity and ability to promote crystallization of the substrate surface are more crucial factors than its roughness.