Effect of ZrSiO_4 on the Friction Performance of Automotive Brake Friction Materials

摘要

Friction-wear properties of the ZrSiO_4 reinforced samples were measured and compared with those of plain bronze based ones. For this purpose, density, hardness, friction coefficient wear behaviour of the samples were tested. Microstructures of samples before and after sintering and worn surfaces were also investigated by scanning electron microscopy (SEM), and the wear types were determined. The optimum friction-wear behaviour was obtained in the sample compacted at 500 MPa and sintered at 820℃. Density of the final samples decreased with increasing the amount of reinforcing elements (ZrSiO_4) before pre-sintering. However after sintering, there is no change in density of the samples including reinforcing elements (ZrSiO_4). With increasing friction surface temperature, a reduction in the friction coefficient of the samples was observed. However, the highest reductions in the friction coefficients were observed in the as-received samples containing 0, 5% reinforced ZrSiO_4. The SEM images of the sample indicated that while bronze-based break lining material without ZrSiO_4 showed abrasive wear behaviour, increasing the amount of ZrSiO_4 resulted a change in abrasive to adhesive wear mechanism. All samples exhibited friction-wear values, which were within the values shown in SAE-J661 standard. With increasing the amount of reinforcing ZrSiO_4, wear resistance of the samples was increased. However samples reinforced with 5% and 6% ZrSiO_4 showed the best results.