7. CONCLUSIONS
A low-steel pad material was tested against a cast iron disc making use of a pin-on-disc tribometer specifically designed for particle measurements. Different nominal contact pressures and sliding velocities combinations were tested. The influence of the aforementioned parameters, the developed frictional power and the system temperature, on particle emissions was analysed. The results indicate that:
System temperature is the most important factor affecting emissions due to the transition temperature which significantly affects the ultrafine levels. Transition temperature is not affected by the testing condition imposed here and lies in the range 170-190°C
Among the typical brake system parameters, frictional power is the most important one. Similar frictional power can provide different outcomes regarding particle emissions in terms of total concentration, specific particle coefficient and size distribution, depending on the system temperature
The specific particle coefficient for the ultrafine fraction is affected by frictional power and system temperature and increases as system temperatures rise
The specific particle coefficient for the coarse and fine fraction is particularly affected by the sliding velocity and shows an increase when nominal contact pressure decreases
