Frictional and Adhesive Properties of Diamond-like Carbon / Silicon Nitride

Diamond-like carbon (DLC) is a unique material that exhibits both low friction and high hardness. This material is being considered as a coating for a wide range of applications, including micromachines, where friction and adhesion play a critical role in performance. In the present study, we seek to understand more fully the fundamental relations that govern the tribology of DLC at the nanoscale. In particular, we wish to understand the way in which humidity tends to reduce the superior frictional properties of DLC. Coatings of DLC were deposited on silicon flats using the plasma source ion deposition process. These coatings are studied using atomic force microscopy, where a nanoscale tip is placed in contact with a sample to measure relative adhesive and frictional forces. Dependence of friction and adhesion on relative humidity, load, and sliding history for a DLC / silicon nitride interface are discussed