The frictional behaviour of LiF single crystals

摘要: A study has been made of the influence initial surface roughness, renewable and non-renewable contaminants, irradiation hardening on coefficient friction for one LiF single crystal (A) sliding another (B) in {100}A A∥{100}B 〈010〉B orientation at ∼ 295 K. The normal load was 1 N, nominal contact pressure 0.1 MPa, velocity 0.2 to 0.6 mm sec−1, amplitude (reciprocate) motion a few millimetres. Any contaminants persisted only cumulative relative displacements ≲ m, that micrometre-scale roughness metres. At steady state presence varied from high 0.45 ultra-high vacuum (∼ 7.5 × 10−8 Pa) “dry” nitrogen-rich air 105 Pa, humidity 15%) low 0.38 “moist” 50%). Irradiation had no effect state. worn surfaces created by steady-state always exhibited grooved topography partly obscured more-or-less adherent layers variously consolidated equiaxed debris particles 100 nm size. Owing action image forces, these contained dislocations. It is suggested determined stress needed shear tiny past as near-rigid bodies.