Quench hardening effect of gray iron brake discs on particulate matter emission

Abstract

In this study, particulate matter produced during the braking of motor vehicles was investigated. In particular, this study focused on the effect of quench hardening of gray iron discs on brake emissions. The disc hardening effect was evaluated with commercial low-steel and non-steel brake pads using a 1/5 scale inertial brake dynamometer equipped with a particle counter. The results indicate that the disc hardening effect was significantly affected by the type of friction material due to different wear mechanisms. The low-steel brake pads produced more brake emissions when using the quench-hardened disc due to the increased aggressiveness of the hardened disc against the brake pad. In contrast, the hardened disc substantially reduced particulate matter emission when using the non-steel brake pads because the pad's surface became more wear-resistant due to the smaller amount of iron transferred from the hardened disc compared to conventional gray iron discs. These results suggest that the iron transfer from the disc to the pad's surface plays a crucial role in brake emissions.