THE EFFECT OF ROTOR DISC MATERIAL ON TRIBO BEHAVIOR OF AUTOMOTIVE BRAKE PAD MATERIALS

This work aims to investigate the effect of two different counterdisc materials, i.e. gray cast iron (GCI) and ductile gray cast iron (DGCI) on tribo behavior of non-commercial frictional materials (NF1, NF2, NF4, and NF5) and two other chosen commercial brake pads (CMA and CMB) under dry sliding contact conditions. The four non-commercial frictional materials were fabricated with various percentages of phenolic binder resin (15 and 20 vol.%) and reinforced with steel fibers (15 and 20 vol.%) using hot press molding methods. Tribo tests were carried out using a small-scale tribo-tester of pad-on-disc type. Friction coefficient and wear of non-commercial and commercial brake pads were measured against each counterdisc (GCI and DGCI) and compared. Then, the friction and wear characteristic are discussed by comparing the experimental results obtained for each kind of cast iron. The results showed that maximum friction coefficient (0.4-0.5) of brake pad was attained at 2.22 MPa applied pressure and 2.1 m/s sliding speed when the frictional brake pad materials were tested against DGCI disc rotor. Meanwhile, similar wear rates for all frictional brake pad materials were sustained at higher applied pressure and sliding speed when tested against either type of rotor discs (GCI and DGCI). The results on the other hand, indicated that non-commercial materials NF1 and NF4, gave better wear resistance compared to other frictional pad materials. NF2 exhibited the lowest wear resistance when tested against GCI and DGCI rotor disc at all applied pressure and sliding speeds. The latter result is referred to the low percentage binder resin in the friction material NF2.