Thu, 06 August, 2020
Historically, brake discs have been manufactured by the casting of iron; a cost-effective method of manufacturing, which produces sufficient material properties required for high-wear and high-temperature environments.
However, the high wear and corrosion that brake discs are exposed to can lead to the generation of fine particles during braking, which can be hazardous to health and the environment. This has led to stricter legal restrictions for next generation vehicles. Alongside this, there are the challenges related to the growth of electrification. Cast iron discs rust after prolonged cycles of limited use and rusted discs can lead to significantly deteriorated braking performance (you may have noticed reduced brake performance after long periods of not driving during lockdown, for example). Electric vehicles primarily rely on regenerative braking systems, leading to significant risks with cast iron discs.
Porsche have recently developed a HVOF thermal sprayed tungsten carbide coating and released it as a cheaper alternative to their performance orientated carbon ceramic discs, but the cost to produce such coatings is still very high, with a high percentage of expensive waste material and limited coating speeds.
The new EHLA process, showcased in a webinar this month by senior project leader Josh Barras, has been shown to have the potential to improve on many of these aspects for brake disc coatings. EHLA provides a metallurgical bond between the disc and the coating, reducing the risk of delamination and increasing the lifespan of the components, while being more material efficient (95%) and coating at higher speeds.