On the improvement of tribological performance using treated betelnut fiber reinforced polyester (T-BFRP) and Teflon composite for automotive applications

This work is an attempt to study the tribological performance of using treated betelnut fiber reinforced polyester (T-BFRP) and a Teflon composite at dry contact conditions. The tribological test is performed using a block on ring (BOR) tribology wear rig. Neat polyester (NP) is the control specimen while antiparallel orientation (AP-O) and parallel orientation (P-O) of the betelnut fiber mats with respect to the rotating BOR stainless steel counterface were considered. The effect of the applied normal loads (5–30 N), the effect of sliding speeds (1.72–3.96 m/s), and the effect of sliding distance (0–6.72 km) were used as the design of experiment (DOE) parameters at dry contact conditions. Concurrently, the results of specific wear rates (Ws), friction coefficients, and temperature profiles of the test specimens together with the roughness average of the composite test samples and stainless steel counterface before and after the test were reported at a different loading conditions. The morphology of the worn surfaces of the test samples was studied through a high-resolution microscope. In summary, it was noted that P-O tends to show a higher Ws range compared to AP-O, namely due to the ease of fiber removal during the sliding wear mechanism. However, the average improvement in Ws for the samples reinforced with Teflon as compared to the T-BFRP composite for the AP-O was 78.8%, respectively, at 2.83 m/s, 30 N, and 6.72 km. The average improvement in friction coefficient was 21.2% for AP-O and 11.5% for P-O at 30 N and 6.72 km at sliding speeds subjected to 1.7 and 3.96 m/s when compared to NP. AP-O exhibits a higher interface temperature as compared to P-O due to the high shear force incurred for AP. However, the average interfaces temperature at 3.96 m/s for AP-O and P-O was reduced by 10.7% and 10.4% as compared to NP. Ra values for the AP-O were relatively high after the test as compared to NP and P-O with Teflon, that is, 1.39 μm, while P-O showed the lowest Ra values of 1.10 μm at the same test conditions. Interestingly, the damage caused by the NP test samples after the test at 30 N and 6.72 km was significantly high, that is, 102.2%, when compared to the virgin counterface. P-O showed the lowest damage (i.e., low Ra values) on the counterface at 44.4%, while AP-O was the second highest at 66.7%. From the microscopy analysis, the damage to the NP samples was severe as the specimen didn’t receive any reinforcement from the fibers. This caused the specimen to crack and form fractures that increased the material removal rate and hence contributed to high tribological wear. P-O showed less damage on the worn samples as the fibers were orientated parallel to the sliding direction of the counterface, which eased the sliding process. AP-O resisted the detachment of the fiber, causing high shear resistance at the sliding zone, which resulted in a much higher Ra value as compared to P-O. In conclusion, adding Teflon in the T-BFRP composite can improve the tribological performance of the composite when compared to NP and nonreinforced Teflon T-BFRP composites