Niobium Alloyed Brake Disc for reduced NVH and emission control

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 technology to meet brake emissions requirements. The proposed process is to alloy the Gray Cast Iron with Niobium. The Niobium addition will reduce wear debris and improve NVH (Noise Vibration Harshness). The test methodology included: Manufacture of disc samples alloyed with Niobium, and 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 treated discs in reduced wear airborne emission requirements. The Niobium alloyed eutectic Gray Cast Iron exhibited an improved wear debris performance for both the Non Asbestos organic (NAO) and Low Metallic (Low Met) friction materials. The Niobium alloyed hypereutectic Gray Iron also performed well with both NAO and Low Metallic friction materials.