High temperature wear properties of multiphase composite: The role of transfer film

The role of transfer film on high temperature wear properties of a multiphase composite for a brake friction material was investigated using a pad-on-disk type tribometer. A novolac resin-bonded composite based on a simple formulation with 6 ingredients (aramid pulp, cashew dust, Cu fiber, graphite, potassium titanate, and zirconium silicate) was used in this study. Results showed that the wear properties of the composite were significantly affected by the temperature at the friction interface when the transfer film was present on the counter face during sliding. In particular, the transfer film on the disk surface was well developed at approximately 200°C, resulting in the improved wear resistance. It suggested that the transfer film on the disk surface effectively prevented direct contacts of the composite onto the counterface. On the other hand, no apparent relationship between transfer film thickness and friction coefficient was found in this experiment.