An investigation of the wear track on DLC (a-C:H) film by time-of-flight secondary ion mass spectroscopy

Tribological behaviors of diamond-like carbon (DLC) on steel under ambient air without lubricant were investigated. DLC (a-C:H) film was prepared on a cemented carbide substrate by radio frequency (r.f.) plasma assisted chemical vapor deposition (PACVD) using a methane (CH4) precursor. The hydrogen content in DLC film was approximately 35 at.%. Pin-on-disk experiments were conducted on DLC-coated disk at the sliding velocity of 52 mm/s under 10 N loading using a steel ball (AISI 52100, 6 min in diameter) as the pin material. After the evaluation of friction coefficient and wear resistance, the transferred layer and wear debris on the wear track of DLC film were investigated using Time-of-Flight Secondary Ion Mass Spectroscopy (TOF-SIMS). The data of TOF-SIMS show the existence of hydrocarbon macromolecules (CnHm) inside the wear track. This result suggests there is a formation of some kind of lubricant materials containing polymer (macromolecule of hydrocarbon), which is generated by the polymerization of DLC film during the tribo-test, contributing thus, to the low friction performance of DLC film. (C) 2001 Elsevier Science B.V. All rights reserved.