Properties of Wear-Resistant MoN Films on Microengineered Substrates

Molybdenum nitride layers were deposited onto the substrates of high-speed steel using high-power impulse magnetron sputtering. To control the tribological properties of these wear-resistant surfaces, a sophisticated pretreatment of the substrates was performed. Both the topography and the composition of the surfaces were modified on a length scale of a few micrometers before the deposition of MoN. For that purpose, a microembossing technique was applied that used specifically prepared diamond stamps. Compositional variations are realized by an additional deposition of silver. Modifying the properties of the wear-resistant surface via this substrate engineering method allowed a significant reduction in the coefficient of friction, a change of the dominant wear process and a possible lifetime increase. Changing the surface topography led to a reduction of friction and, therefore, to reduced mechanical work supplied to the surface. Occurring wear was reduced accordingly. The introduction of silver further reduced the mechanical energy that was available for the abrasion process and led to an additional increase in the lifetime of the surface. It was concluded that not only the wear volume, but also the relevant wear mechanisms could be influenced via a substrate modification.