Automotive

Description

Automotive

Measurements at low temperatures are particularly required when the difference between the internal and free energy of a material becomes small. This is an experimental problem fraught with technical difficulties.

In practice, thin lubricant films significantly reduce friction force and maintain mild wear conditions over a considerable range of normal loads and speeds. Amontons’ law of the direct proportionality of friction force to normal load is an objective criterion for evaluating the safe operating limits of friction contacts.

Electrostatic forces are responsible for the “stick-slip” phenomenon; they can account for a significant part of the friction force in the “extreme pressure” region, especially due to the adhesion force of extremely thin films. Strong stick-slip motion is accompanied by mild wear, while the onset of severe “tearing”, expressed by significant deviations from Amontons’ law, dampens the abrupt movements between the metal test elements.