Tribological study of gray cast iron with automotive brake linings: The effect of rotor microstructure

Experimental studies of friction characteristics were conducted using gray cast iron and automotive brake linings. The gray iron samples were manufactured to have different microstructures by changing the carbon equivalent and cooling speeds of melts and two different types of non-commercial brake linings (non-steel and steel-containing linings) were used as a counter material. Friction tests were performed on a pad-on-disk type tribotester and particular emphases were given to the effect of graphite flakes and ferrite in the gray iron disks on fade phenomena and the level of the coefficient of friction. Results showed that the coefficient of friction increased with the amount of graphite flakes on the gray iron and the effect was more pronounced in the case of using steel-containing linings. The amount of ferrite phase on the disk surface showed little influence on the coefficient of friction. Fade resistance of non-steel linings was improved with the increase of graphite flakes on the disk surface and steel-containing linings showed good fade resistance regardless of graphite contents in the gray iron disks.