Impact of relative humidity and deposition parameters on the tribological behavior of soft DLC coatings

摘要: When diamond-like carbon coatings are produced with plasma-assisted CVD, a softer but thicker DLC variant with excellent tribological behavior can be achieved. Due to great adhesion and load-bearing capacity, they can be deposited on low-alloy steels, commonly used in mechanical engineering, to reduce energy consumption and extend the lifespan of machine components.In this work, soft a-C:H coatings were deposited over AISI 4140 steel using a modified commercial PA-CVD system, with acetylene as carbon precursor. Two kind of coatings were deposited: Si free (a-C:H) and Si doped (a-C:H:Si). Adhesion, mechanical properties, and film structure were analyzed. Tribological behavior was evaluated with Pin-on-Disk tests using an alumina ball as counterpart and 12 N normal load. At constant room temperature, three different relative humidity conditions were tested: dry, room and wet. The frictional force …