24 Tribology of Diamond , Diamond - Like Carbon , and Related Films

Diamond, diamond-like carbon (DLC), and other related materials (i.e., carbon nitride and cubic boron nitride [CBN]) are some of the hardest materials known and offer several other outstanding properties, such as high mechanical strength, chemical inertness, and very attractive friction and wear properties, that make them good prospects for a wide range of tribological applications, including rolling and sliding bearings, machining, mechanical seals, biomedical implants, microelectromechanical systems (MEMS), etc. The dry sliding friction and wear coefficients of these materials are among the lowest recorded to date (Brookes and Brookes, 1991; Feng and Field, 1991; Field, 1992; Miyoshi, 1995; Erdemir, 2001a,b). In fact, if they were inexpensive and readily available, they would undoubtedly be the materials of choice for a wide range of applications. Besides their exceptional mechanical and tribological properties, most of these superhard materials offer broad optical transparency, high refractive index, wide bandgap, low or negative electron affinity, transparency to light from deep UV through visible to far infrared, excellent thermal conductivity, and extremely low thermal expansion. Briefly, these exceptional qualities make diamond, DLC, and other related materials ideal for numerous industrial applications in addition to tribology. Ali Erdemir Argonne National Laboratory