Achieving Euro 7 Compliance: Cost-Effective Brake Wear Particle Emissions and Performance with FNC-Smart ONC® GCI Rotors

Advanced ferritic nitrocarburizing process combined with a specialized post-oxidation treatment described as FNC + Smart ONC® [1] is developed for brake rotor applications. The process can be applied to standard grey cast iron brake rotors, significantly reducing PM 10 emissions to levels below the Euro 7 limits for most vehicles equipped with at least some recuperative braking capabilities, all without compromising performance. Finished grey iron brake rotors, ferritic nitrocarburized and post oxidized were evaluated according to several industry standards. The standards include SAE J2707B (Block Wear Test including Highway) [2], GRPE-90-24 Rev.1 Emission Test (Full WLTP Brake Cycle 6 Times) [3], and SAE J2522 (AK-Master Performance) [4]. Nitrocarburized post oxidized brake rotors were compared to untreated grey iron rotors exposed to several friction materials. Ferritic nitrocarburizing and post oxidation addresses the issue of corrosion, which is particularly relevant for brake rotors that experience less use in vehicles with recuperative braking systems. Improved corrosion performance of ferritic nitrocarburizing and post oxidation could potentially eliminate the need for the conventional practice of painting rotors. Corrosion performance was validated by conducting cyclic corrosion according to SAE J2334 (Cyclic Corrosion, 36 cycles) [5]. A reduction in brake emissions by 50 percent was achieved for existing vehicles without recuperative braking systems.