The braking system is an essential component of automotive safety. The durability and quality of the brake pads are critical factors to consider in order for the braking mechanism to function properly. A brake pad is a component of a vehicle that holds the wheel rotation in place so that braking can take place.
Binders, reinforcement, fillers, and abrasives make up the friction material in brake pads (Figure 1). Binders are the materials that hold all of the components of the pads together. This material must have a high and stable friction coefficient, be resistant to high temperatures and rapid temperature changes, and be lightweight. Reinforcement is a fibrous material that is added to binders to improve their mechanical properties. The types of reinforcing materials used have a significant impact on the durability of brake pads. Asbestos is a fantastic reinforcing fibre. However, because of the danger involved, a replacement material is required. Fillers are used to fill the gaps between the other components of the brake pads, while abrasive ingredients are used to change the coefficient of friction. Because of their hardness, steel, refractory oxides, cast iron, quartz, or silicates are used as additives to improve the friction coefficient between the disc and the brake pads. By increasing the friction coefficient, the service life of the brake pads is extended.
Steelwool or steel fibres are commonly used in the formulation of friction materials to improve high temperature fade resistance and reduce brake pad wear.
Steel fibres were widely used as asbestos substitutes in semi-metallic formulations because they increase the friction coefficient of the composite material and reduce fading through thermal diffusivity.
There are three types of friction materials available on the market: sintered metals, non-asbestos organic (NAO), and semi-metal (SM). Iron powder, steel fibres, graphite, rubber, organic fibres, ceramic, abrasives, lubricants, and fillers are among the materials used. A phenolic resin bonds several materials together to form the friction material.