INTRODUCTION
The friction material in the automotive brake system has been considered as one of the key components for overall performance of a vehicle. This is because it plays crucial roles in various aspects of the brake performance such as a stopping distance, pedal feel, counter disk wear and brake induced vibrations. A great deal of effort has been given to improve the performance of the friction material and multiphase composites have been used as a brake friction material from the early stage of vehicle development since a monolithic material has never been successful for commercial brake friction materials.
More than 10 ingredients have been used to produce commercial brake friction materials, expecting that each ingredient provides beneficial roles for brake performance under different braking conditions. Brake pads typically comprise the following sub-components a) Frictional additives, which determine the frictional properties of the brake pads and comprise a mixture of abrasives and lubricants b) Fillers, which reduce the cost and improve the manufacturability of the brake pads; c) a binder, which holds components of a brake pad together d) reinforcing fibers, which provide mechanical strength.
Before the ban on usage of asbestos in brake linings was imposed in 1989, Asbestos was the most preferred filler material as it is thermally stable upto 5000C, helps regenerate friction surface during use, insulates thermally, strong and flexible and mostly, it is available cheap. Since the ban on asbestos, researchers have struggled to come up with an equally efficient alternative. Barites, mica and cashew dust are amongst some of the materials that have been considered for use as fillers.
FLY ASH AS FUNCTIONAL FILLER IN BRAKE LINING: Coal combustion byproducts are the inorganic residue left behind during the coal combustion