Nanotribology properties of extremely thin diamond-like carbon films at high temperatures with and without vibration

Extremely thin diamond-like carbon (DLC) films were deposited by filtered cathodic vacuum arc (FCVA) and electron cyclotron resonance-chemical vapour deposition (ECR-CVD) methods. The nanotribological properties of these films at high temperatures were evaluated using atomic force microscopy. At room temperature (RT), the FCVA-DLC films showed superior nanowear resistance than the ECR-CVD-DLC films. Conversely, at high temperatures in vacuum, the wear increased rapidly. The friction force of the FCVA-DLC films was low at RT in air and vacuum, but it was very high at high temperatures in vacuum. The lubricous adsorbate was removed by sliding at high temperatures. Hard brittle wear debris produced by high friction acted as an abrasive and increased the wear. In contrast, the friction force of the ECR-CVD-DLC films was low at high temperatures, corresponding to a low wear rate. Thus, the lubricous tribochemical products reduced the friction and wear. When the samples were vibrated, the wear depth of the FCVA-DLC films decreased at high temperatures, while that of the ECR-CVD-DLC films increased. Removal of the hard abrasive wear debris from the FCVA-DLC films decreased the wear by vibration, while removal of lubricous tribochemical products of the ECR-CVD-DLC films increased the wear by vibration.