Mo–S–Ti–C Nanocomposite Films for Solid-State Lubrication

A Mo–S–Ti–C nanocomposite film with both high-crystalline MoS2 in (002) basal planes and high hardness was successfully synthesized in the condition of pure MoS2 films growing with edge-terminated surface. The evolution of their structure and the transformation of crystal orientation during film growth were investigated by X-ray diffraction (XRD) patterns and focused ion beam combining with the transmission electron microscopy (FIB/TEM). TEM revealed that the MoS2 edge sites usually considered as catalytic materials in catalysis field can provide active sites for titanium and carbon atoms aggregating in deposition. This aggregation of dopants not only largely passivates the activated MoS2 edge sites and induces the initial (100) textured MoS2 lamellar gradually transforming into (002) orientation but also effectively reduces the damage the dopants do to the highly ordered MoS2 crystallites. As a result, a Mo–S–Ti–C composite film with well-crystallized MoS2 in (002) basal planes was formed. The nanoindented experiments reveal that the hardness of this nanocomposite film reaches up to 6.81 GPa. Benefiting from the enhanced hardness and well-crystallized MoS2 in (002) basal planes, the corresponding pin-on-disk tribotests indicate that this nanocomposite film exhibits low friction coefficient (about 0.02) and high-wear resistance whether in vacuum or ambient air.