Study of Multilayer Treatments of Nitrocarburizing with N and Si-doped DLC Films in Improving the Wear Resistance of AISI M2 Steel

Diamond-like Carbon (DLC) films demonstrate substantial hardness, minimal friction, and exceptional wear resistance when applied to metal substrates; however, they face challenges related to inadequate adhesion. Furthermore, concerns about thermal stability are prevalent in DLC films, particularly concerning cutting tools, where processing temperatures may reach significant levels. To mitigate these issues, incorporating various dopants and applying multilayer treatments may enhance adhesion, thermal stability, and wear resistance while simultaneously decreasing the coefficient of friction. This study systematically examines the effects of nitrogen and silicon doping on DLC films applied to M2 steel. It employs multilayer treatments to evaluate their influence on wear resistance, employing a fixed ball wear test that monitors wear progression by interrupting the test at various intervals. Plasma treatments, including nitriding, nitrocarburizing, and DLC coatings, were evaluated independently and in combination. A combination of DLC coatings with nitrocarburizing proved to be better for wear resistance when both the coating and the compound layer present a controlled thickness and high hardness, promoting low friction and avoiding debris formation. The findings reveal that Si-doped DLC combined with nitrocarburized layers significantly improves wear resistance and adhesion, highlighting the benefits of integrating duplex treatments with DLC doping to enhance coating performance.