THE FRICTION AND WEAR OF SOLIDS AT VERY LOW TEMPERATURES.
Final rept. 1 Apr 65-1 Apr 68,
CAMBRIDGE UNIV (ENGLAND) CAVENDISH LAB
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Sliding friction and wear studies have been carried out on gold, silver, copper and nickel, tantalum, iron, molybdenum and tungsten, cobalt, beryllium, zirconium and titanium in ultra high vacuum, at temperatures between 20K and 300K. Changes in friction with temperature have been small, but those which have occurred have been accompanied by a change of surface deformation. With face centered cubic metals, which remain ductile to the lowest temperatures, a transition from a continuously grooved track to a torn track, accompanied by a drop in the coefficient of friction, occurred when the initial work hardening rate exceeded 135 kgsq mm per unit strain. With the body centered cubic metals drops in friction at low temperatures could be correlated with their brittle ductile transition properties. The hexagonal metals showed no change in friction with temperature, but as a group, showed an increasing amount of friction and wear the more ductile they were. Author
- Metallurgy and Metallography