Microwear Mechanisms of Silicon Sliding Against Diamond in Water Vapor

Abstract

Microwear mechanisms of single-crystal silicon (111) in water vapor have been investigated. A diamond pin with a radius of 10 μm was used as a pin specimen. All tests were carried out in the chamber of environmental scanning electron microscopy (ESEM), with which contact point could be observed simultaneously during the sliding test. The water vapor pressure was changed from 40 Pa (0.3 Torr) to 2667 Pa (20 Torr). Three different wear modes were observed in the tests and consolidated as wear mode diagram according to initial maximum Hertzian contact pressure and friction coefficient. These wear modes are

A No removal of material

B Microcutting of feather-like wear particles

C Fracture

Corresponding to these wear modes, the friction coefficients are 0.07 ∼ 0.13 in Wear Mode A, 0.19 ∼ 0.23 in Wear Mode B and 0.16 ∼ 0.18 in Wear Mode C. Transitions of wear mode are not influenced by water vapor in the range of 40 ∼ 2667 Pa. Friction coefficient changes by the change of water vapor pressure in Range A but does not change in Ranges B and C.

KEY WORDS:

• Silicon
• Wear
• Friction
• Diamond