Effect of two different sulfide coated steel fiber towards tribo performance – An interface study

The purpose of friction material is to decelerate a vehicle by transforming the kinetic energy of the vehicle into heat, via friction, and dissipating that heat to the surroundings. A lot of heat is generated at the contact plateaus formed by the reinforcing fibers. Therefore, inorder to dissipate the heat, steel fibers were coated with FeS and SnS and accordingly brake pads were made and termed as DBF and DBS. Another brake pad with similar formulation but with a mixture of steel fiber, FeS and SnS was made (designated as DBO) for comparison. All three brake pads were tested in an inertia brake dynamometer with a typical schedule. The speed spread (100/50 Kmph) 0.6g and effectiveness variation of all the pads are fallen in the required range. The fade I of DBO is observed 32.8% lesser whereas for DBS and DBF, it is observed10% and 15.7% more than the standard values, respectively. DBF and DBO have shown 25.4% and 39.6% more wear than DBS, respectively. Further, it is observed a more consistent µ during single braking to identify fade during stops in the second effectiveness test. It is evidenced for the increase in the life of the friction film formed by the sulfide coated fibers in DBS which has increased its wear resistance (Max Δµ = 0.10 for DBS, 0.29 for DBF, and 0.30 for DBO). It is also noticed that the radial wear of all three brake pads was greater than the tangential wear and their ratios are 1.36, 1.40 and 1.55, respectively for DBS, DBF and DBO. Moreover, the optimization has revealed the DBS as best performer friction materials formulation.