Tribo-Evaluation of Some Candidate AMMC Discs Sliding Against Automobile Brake Pad

Abstract

Braking systems are one of the most important controlling systems used in the automobiles. Conventionally grey cast iron is used to make the Disc material. However, it is heavy which results in higher specific fuel consumption. Due to the ever increased competition regarding power consumption during the braking application, requirement of light weight technology and due to continuously changing brake friction material, now-a-days automotive sectors are shifting their attention on the alternative materials for brake rotors that can perform better than existing material in terms of tribological, thermal and mechanical aspects. Particulate reinforced aluminium MMCs are promising candidates for automotive applications since they offer high specific stiffness and strength, good wear resistance and suitable thermal properties; furthermore, they are readily available at reasonable prices and can be processed using conventional technologies and hence gained wide attention for the tribological development during the last decade. Although, a lot of research is done for the formulation of new brake friction material, however, relatively little study has been made till date on the brake disc material especially using composite material. Despite of the fact that AMMC is one of the most widely researched matrix materials amongst all the promising types of composites , however, a very few studies are available in the literature which investigated the tribological behaviour of Al-B4C and Al-SiC-B4C hybrid composites sliding against commercial brake pads. Hence, to replace the conventional CI as brake rotor material, further investigation can be carried out using various AMMCs as disc material. The present research is carried out in this direction using four different types of AMMCs along with the commercial cast iron disc materials, all of which slides against the commercial brake pad. For this purpose, AMMCs are fabricated by stir casting, as well as commercial discs and pads are procured. Then they are subjected to mechanical and tribological characterization using hardness testing, Optical microscopy, SEM, EDS and XRD. The wear and friction response and worn surface morphology and elemental compositions on the wear tracks reveal some interesting facts about the AMMC-Pad tribopairs. The investigation shows that Al6061composite and its hybrid can be carefully developed for the desired tribological properties required for the brake rotor application for reliable, long life and high performance application. The research outcome will definitely help in understanding the meaningful market potential of developing AMMC disc in place of conventional CI rotor.