Niobium Alloyed Brake Disc for reduced NVH and Emission Control

<div class="section abstract"><div class="htmlview paragraph">Recent regulations limiting brake dust emissions have presented many challenges to the brake engineering community. The objective of this paper is to provide a low cost, mass production solution utilizing well known existing technologies to meet brake emissions requirements. The proposed process is to alloy the Gray Cast Iron with Niobium and subsequently Ferritic Nitrocarburize (FNC) the disc. The Niobium addition will improve the wear resistance of the FNC case, reducing wear debris.</div><div class="htmlview paragraph">The test methodology included: 1. Manufacture of disc samples alloyed with Niobium, 2. Finish machining and ferritic nitrocarburizing and 3. Evaluation of airborne wear debris utilizing a pin-on-disc tribometer equipped with emission collection capability. The airborne emission and wear surfaces were further analyzed by Scanning Electron Microscopy, Energy Dispersive techniques (SEM-EDS), X-Ray Diffraction and Optical Microscopy. The cast iron test matrix included four groups; Unalloyed eutectic 4.3% Carbon Equivalent (CE), Unalloyed hypereutectic >4.3% CE, Niobium alloyed Eutectic and Niobium alloyed hypereutectic gray cast iron. The results demonstrate the advantages of Niobium alloyed FNC treated discs in reduced wear and meeting Euro7 airborne emission requirements. The Niobium alloyed eutectic Gray Cast Iron plus FNC treatment exhibited the best wear debris performance for both the Non-Asbestos organic (NAO) and Low Metallic (Low Met) friction materials. The Niobium alloyed hypereutectic Gray Iron plus FNC treatment also performed well with both NAO and Low Metallic friction materials.</div></div>