OBRABOTKAMETALLOV Vol. 27 No. 2 2025 technology Literature Review Composition of Brake Friction Materials Automotive brake friction materials are complex mixtures consisting of numerous components designed to provide the required frictional properties and wear resistance. They can be classified into four main groups: – Binders provide cohesion for all other ingredients. – Reinforcing fibers enhance the strength of the composite matrix. – Friction modifiers provide the required level of lubrication, stabilize the coefficient of friction, and regulate the formation of tribological films on the contact surface. –Fillers are primarily used to reduce the cost of the composite and partially modify the characteristics of the friction material [2, 3]. Fig. 1 schematically presents the key functions of the main components of a brake friction composite. The selection of each ingredient is determined by the need for its properties to meet the required functional requirements. Fig. 1. Key roles of crucial components of brake friction composites Fibers Fibers play a crucial role in the composition of brake friction materials, providing the necessary strength and durability under the high loads that occur during braking. The introduction of reinforcing fibers contributes to increasing the overall strength of the material [3]. When selecting fibers for brake pad composites, characteristics such as high strength, friction stabilization, wear resistance, low thermal conductivity, noise absorption, and compatibility with binders are taken into account [7]. Aramid and basalt fibers can be used as reinforcing fibers in brake pad compositions. Aramid fibers, providing high strength and wear resistance, are optimal for heavy-duty braking conditions. Basalt fibers, due to their exceptional heat resistance, are recommended for high-temperature braking modes [9–10]. Fillers Fillers are important components of brake friction composites, contributing to the reduction of noise and vibration, as well as increasing wear resistance. The introduction of fillers improves the performance characteristics of brake pads friction composites. The most common inorganic fillers include calcium carbonate, exfoliated vermiculite, mica, barium sulfate, kaolin clay, cashew dust, and alkali metal titanates. Calcium carbonate (CaCO₃) allows reducing cost and increasing wear resistance, which extends the service life and durability of brake pads. The use of this filler reduces material loss during braking and increases overall wear resistance. Barium sulfate (BaSO₄), which has high thermal stability, is often used as a filler because it can withstand extremely high temperatures generated during braking [5–11].
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