The Effects of Corrosion on Particle Emissions from a Grey Cast Iron Brake Disc

Reducing exhaust emissions has been a major focus of research for a number of years since internal combustion engines (ICE) contribute to a large number of harmful particles entering the environment. As a way of reducing emissions and helping to tackle climate change, many countries are announcing that they will ban the sale of new ICE vehicles soon. Electrical vehicles (EVs) represent a popular alternative vehicle propulsion system. However, although they produce zero exhaust emissions, there is still concern regarding non-exhaust emission, such as brake dust, which can potentially cause harm to human health and the environment. Despite EVs primarily using regenerative braking, they still require friction brakes as a backup as and when required. Moreover, most EVs continue to use the traditional grey cast iron (GCI) brake rotor, which is heavy and prone to corrosion, potentially exacerbating brake wear emissions. This study concentrates on emissions from a conventional grey cast iron friction brake before and after exposure to a corrosive environment. It was found that the effect of corrosion increases both the number and mass of particle emissions by over 50% and inhibits braking performance by reducing the coefficient of friction. The surface of the brake disc was also found to be affected by corrosion as many crevices and pits were formed.