ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00576769
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