Microstructure of amorphous diamond-like carbon thin films and changes during wear

Using scanning and transmission electron microscopy, we investigate the microstructure of diamond-like carbon (DLC) thin films deposited in an electron-cyclotron resonance plasma. During pin-on-flat wear experiments, the amorphous DLC films are found to be a source for formation of transfer film and wear track debris with composite microstructure. The transfer film is observed to consist of an amorphous matrix with dispersed microcrystalline and tubular particles. The debris from the wear track represents separated bundles of aligned tubular particles and clusters of microcrystalline particles. The lowering of the coefficient of friction measured during the wear experiments is related to the formation of the composite transfer film and its stable low value—to the possibility that the randomly oriented tubular particles from the transfer film engage in rolling friction in the process of their organization into aligned bundles.