Ph.D. Tezi Görüntüleme

      Basarit, Fiberfrax, stone wool, chopped E-glass fiber, steel-wool, Kevlar-pulp and tea fiber (which is obtained as waste material in the tea production) were used to manufacture the specimens. In addition an asbestos reinforced and non-asbestos brake pad were bought from the market for comparison. Some mechanical and physical properties of the produced samples were also studied in addition the friction and wear behaviors. The effects of fiber content on friction and wear characteristics of Basarit and stone wool containing samples were investigated at 1.0 MPa normal pressure and 6 m.s-1 sliding velocity by changing the fiber volume ratios between 7-40 %. The coefficient of friction increased and specific wear rates decreased with increasing fiber content up to ~30 %. Thermal fade properties were better at higher fiber contents. Same trends were observed for the other investigated fibers. Average coefficients of friction of the samples containing Basarit 7-30 % were measured 0.33 and 0.48 as respectively.

      Specific wear rates of the studied composites having approximately same fiber volume fractions show that wear was in the order of Kevlar-pulp, tea fiber, Basarit, E-glass fiber, stone wool, Fiberfrax and steel wool. Increase of normal pressure from 0.5 MPa to 1.0 MPa leads to decrease in average coefficients of friction on Kevlar-pulp, E-glass and stone wool containing samples. Average coefficients were found decreasing with increasing sliding speed from 2 m.s-1 to 12 m.s-1. Obtained results indicated that Kevlar-pulp was more sensitive to sliding speed then other fibers. X-ray diffraction studies of wear particles showed that magnezioferrit (MgFe2O4) and sillimanit (Al2SiO5) were formed at the friction surface of steel wool containing samples.

      The results of the studies revealed that Basarit, stone-wool, E-glass fiber; Fiberfrax and steel wool can be used as substitute for asbestos. Kevlar-pulp and tea fiber also can be used with inorganic fibers for manufacturing hybrid friction materials.

      Key words: Brake pad, Friction material, Non-asbestos friction material, Friction, Wear