Environmentally Friendly Protective Coatings for Brake Disks

Recently, environmental concerns have initiated intensive research and development in the field of friction brake systems with the aim to minimize particle emission. First brake systems with thermally sprayed protective coatings applied to grey cast iron brake disks have been introduced in automotive industries and have proven to strongly reduce particle emission. However, there is a desire to use materials that show improved environmental compatibility and lower price using processes that permit improved performance of protective coatings with reduced production costs. Different approaches concerning the choice of base and coating materials as well as the production processes are discussed with respect to technological, economic and ecological aspects. Besides grey cast iron, aluminum alloys are considered as base materials. Regarding coating production, HVOF spraying and laser cladding offer specific advantages and recent progress concerning the expansion of their production rate limitations is presented. Finally, novel feedstock materials that show excellent compatibility with stainless steel and aluminum alloy matrices have been developed and applied for coating production.