TRIBOLOGY OF DIAMOND-LIKE CARBON-FILMS FROM GENERIC FABRICATION ROUTES INVESTIGATED BY LATERAL FORCE MICROSCOPY

The tribological characteristics of diamond-like carbon (DLC) films ha ve been studied by lateral force microscopy (LFM). Specimens from two fabrication routes, ion-beam assisted deposition and chemical vapour d eposition, have been investigated. Thick (micrometres) and thin (a few nanometres) firms from both routes have been considered, as have the service environments of ambient air and vacuum. lateral force data wer e calculated from 'friction loops', obtained as functions of load, sur face topography, scan speed and service environment. An identical meth odology and LFM probe were used throughout the series of measurements in order to ensure internal consistency. and the validity of the metho dology was checked against measurements on epitaxially grown Si. A lin ear dependence was observed between lateral force and force loading up to ca 5 mu N, in accord with a multi-asperity model, thus allowing de termination of coefficients of friction that ranged from 0.05 to 0.15. The results showed that adhesive interactions contributed up to 2 mu N to the overall dynamic load. Meniscus interaction played a minor rol e in comparison to that from tribe-generated electrostatic forces. The experiments show that LFM methodologies have value and relevance to t he science and technology of tribology, especially when the required s patial resolution cannot be obtained with the traditional macroscopic techniques.