a) During sliding of a cylindrical steel pin against a steel disc in a pin-on-disc test in air, the coefficient of friction is initially around 0.7, but then falls to 0.5 as the test proceeds. At the end of the test, the wear track on the disc is rough and black in colour, with a black powder on the disc surface outside the wear track; chemical analysis of the wear track shows a high oxygen level.
a) During sliding of a cylindrical steel pin against a steel disc in a pin-on-disc test in air, the coefficient of friction is initially around 0.7, but then falls to 0.5 as the test proceeds. At the end of the test, the wear track on the disc is rough and black in colour, with a black powder on the disc surface outside the wear track; chemical analysis of the wear track shows a high oxygen level.
(b) A test identical to that described in part (a) is conducted, but this time the test is conducted in vacuum. The coefficient of friction remains high through the test, the wear volumes are much greater, and the track on the disc surface following the test is very rough and silvery in colour.
(c) A test identical to that described in part (a) is conducted, but this time the test is conducted in air at 300 ◦C. At the end of the test, the wear track on the disc is very smooth (shiny) and black in colour, with no debris on the disc surface outside the wear
track; chemical analysis of the wear track shows a high oxygen level.
Step by step
Solved in 2 steps
