The frictional behaviour of LiF single crystals |
| |
Authors: | E A Schlanger C Y Huang N H Macmillan |
| |
Affiliation: | (1) 265 East 66th Street, No. 44A, 10021 New York, New York, USA;(2) Materials Research Laboratory, The Pennsylvania State University, 16802 University Park, Pennsylvania, USA;(3) Department of Mechanical Engineering, Oregon State University, 97331 Corvallis, Oregon, USA;(4) Present address: Division of Ceramic Engineering and Science, New York State College of Ceramics at Alfred University, 14802 Alfred, New York, USA |
| |
Abstract: | A study has been made of the influence of initial surface roughness, renewable and non-renewable surface contaminants, and irradiation hardening on the coefficient of friction for one LiF single crystal (A) sliding on another (B) in {100}A<010>A {100}B 010 B orientation at 295 K. The normal load was 1 N, the nominal contact pressure 0.1 MPa, the sliding velocity 0.2 to 0.6 mm sec–1, and the amplitude of the (reciprocate) motion a few millimetres. Any influence of non-renewable contaminants persisted only for cumulative relative displacements 0.1 m, and that of micrometre-scale initial surface roughness only for a few metres. At steady state in the presence of renewable contaminants the coefficient of friction varied only from a high of 0.45 in ultra-high vacuum ( 7.5 × 10–8 Pa) and dry nitrogen-rich air ( 105 Pa, relative humidity 15%) to a low of 0.38 in moist nitrogen-rich air ( 105 Pa, relative humidity 50%). Irradiation hardening had no effect on the coefficient of friction at steady state. The worn surfaces created by steady-state sliding always exhibited a grooved topography partly obscured by more-or-less adherent layers of variously consolidated equiaxed debris particles 100 nm in size. Owing to the action of image forces, these particles contained no dislocations. It is suggested that the coefficient of friction was determined at steady state by the stress needed to shear these tiny particles past one another as near-rigid bodies. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|