Tribological phenomena, such as friction, are highly scale dependent. Macroscopic friction laws are typically not applicable to sliding nanoscale/microscale contacts and macroscopic surface interactions are governed by nano/micro-scale asperity contacts, which ultimately determine their tribological behavior. Consequently small scale friction measurements are gaining prominence in tribological research to better understand and control macroscopic friction behavior.
The application of surface coatings and thin films, multiphase alloying and phase segregation, microstructure control, lubricants, and composite structuring are common ways to improve friction properties of mechanical systems. The ability to characterize and understand how individual phases in composites and multiphase materials contribute to overall frictional behavior is important to developing higher performance materials. Friction becomes increasingly problematic with small scale actuators, such as MEMS. The large surface to volume ratios of these devices can cause surfaces to unexpectedly stick together, rendering the device inoperable. The ability to quantitatively characterize, modify, and control frictional forces at the nano and microscales is critical for developing higher efficiency and more reliable products.