The materials used for brake pads or brake bands must be able to withstand the frictional force of braking as this mechanical component receives the brunt of that process.
As ceramics have long been praised for their heat resistance and durability, they have become a prime choice for brake pad manufacturers. The extreme hardness, resistance to weathering and wear, high stiffness, resistance to chemical corrosion and compressive strength of these non-metallic substances heighten their applicability. Automotive, agricultural and transit industries make use of both commercial and industrial grade ceramic brake pads. Ceramics begin as a granular powder that is purified before being measured and often combined with other ceramics or substances such as metal shavings.
The friction materials are then bonded together by manufacturing techniques such as sintering, firing, hot pressing, hipping, extrusion, fusing, slip or pressure casting, injection molding and deposition many of which can be utilized in the production of a wide variety of brake pads. Because these composites retain the positive qualities of each element entered into them, they can be made specific to a given industrial or commercial application. Alumina, or aluminum oxide, boron carbides and silicon carbide are the most common of the advanced, technical and engineering grade ceramics used in the production of brake pads.
The basic process of braking relies heavily on the functionality and efficiency of the brake pad. When a lever or pedal is pressed, it sets into motion a chain of events beginning with the release of brake fluid which is put under pressure and travels to the braking mechanism of each wheel where a small hydraulic pump engages the shoe or caliper. Ceramic brake pads, attached with strong adhesive glue or rivets, are thus pressed against the spinning surface of the wheel or disc. The friction created by contact between the two materials causes the wheel to slow in proportion to the amount of pressure applied.
Because ceramics maintain their structural integrity even in the presence of tremendous heat, they offer increased stopping power as compared to metallic counterparts which experience thermal expansion. While a grating or squealing noise is produced by this friction, ceramics generate a frequency beyond human hearing capabilities and thus are less of an annoyance to consumers. Reduced dust is another significant benefit of ceramic brake pads. The friction inherent in braking grinds both the rotor and the pad, generating small pad fragments that break off and can cause a loss of traction or vibration.
The durability and heat resistance of ceramics significantly reduce the amount of brake-dust generation. Shimmed, chamfered, and slotted ceramic brake pads further reduce heat expansion related cracks and noises.