A pin-on-disc study of the rate of airborne wear particle emissions from railway braking materials

Abstract

The current study investigates the characteristics of particles generated from the wear of braking materials, and provides an applicable index for measuring and comparing wear particle emissions. A pin-on-disc tribometer equipped with particle measurement instruments was used. The number concentration, size, morphology, and mass concentration of generated particles were investigated and reported for particles 10 nm to 32 µm in diameter. The particles were also collected on filters and investigated using EDS and SEM. The effects of wear mechanisms on particle morphology and changes in particle concentration are discussed. A new index, the airborne wear particle emission rate (AWPER), is suggested that could be used in legislation to control non-exhaust emissions from transport modes, particularly rail transport.

Particle Emissions From Rail Traffic: A Literature Review

“…It is suggested that differences between the dominant wear mechanisms cause the differences in wear particle shape (Stachowiak et al, 2008). This suggestion was confirmed by Abbasi et al (2012b) in a laboratory study of airborne wear particles. Figure 2 shows an image of particles from diesel exhaust.…”

“…Abbasi et al (2012b) suggested a method for measuring the airborne wear particle emission rate (AWPER) from wheel-rail contacts and braking materials. This method can be used by manufacturers to demonstrate the competitive advantage of their products.…”

“…Two report data from laboratory measuremets (Abbasi, 2011 andAbbasi, 2012b) and one discusses emission rates in the Stockholm subway (Johansson, 2005). Other sources address particle concentrations, inherently reflecting emission rates.…”

“…The choice of brake pad materials has implications both for the emission rate of particles (Abbasi et al, 2012b) and of the substances emitted. Therefore optimal choices of materials may reduce risks of adverse health effects.…”

Regenerative braking in high speed railway applications: Analysis by different simulation tools

“…In particular, reduced wear and prolonged life of brake pads and discs also produce benefits in terms of pollution since the wear produce solid particles and contaminants whose impact on the surrounding environment is still the matter of monitoring and research [1][2] [3].…”