Friction and wear affect almost all moving mechanical systems. By some estimates, nearly a quarter of the world’s energy output is spent in overcoming friction.1 About 70% of equipment failures are in some way attributable to wear and fatigue. Granted, strong friction forces are sometimes needed; brakes, tires, and continuously variable transmissions, for example, couldn’t operate without them. But in many cases, alleviating friction would save energy, help the environment, and boost productivity.

Since prehistoric times, human beings have sought ways to minimize friction and its attendant ills. Before the 1990s, however, tribologists generally assumed that the friction coefficient—the dimensionless ratio of the friction force to the normal load across contacting surfaces—could never fall below 0.1 in most practical systems. The friction coefficient of wood sliding against wood is typically 0.2 or larger; for clean metal surfaces under dry conditions, it can be larger than 1.

A quarter of...

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