Tribological behavior of short fiber reinforced thermoplastic composite was investigated experimentally and theoretically. Short carbon fiber and glass fiber reinforced poly(amide-imide) composites were selected as the testing material. Titanium oxide filled poly(amide-imide) was also tested for comparison with fiber composites.
Block-on-ring type wear test was performed for 24 hours with three different sliding conditions. The block specimens were prepared from the molded composites and the ring counterface was prepared from stainless steel.
Frictional behavior of the three thermoplastic composites was explained by considering the role of wear particles generated during sliding and the action of wear film transferred to the counterface. Wear surface of the glass fiber reinforced specimen had many grooves with broken and removed fibers, while the carbon fiber composite showed few fibers being removed from the surface and many fibers polished by motion of counterface.
Stress analysis was performed to investigate the stress ditribtuion around the fibers exposed to the surface. Results of stress analysis showed that much larger equivalent stress was obtained at the surface of the glass fiber than at the carbon fiber. It is probable that debonding occurs at the glass fiber-matrix interface due to concentrated stress and the short fibers are removed from the surface by pulling, buckling, or pushing.
