As a core component of the automotive braking system, the performance of the brake pump directly affects driving safety. During braking, cemented carbide balls, as key wear-resistant elements, bear the heavy responsibility of transmitting pressure, sealing fluid, and resisting wear. Taking typical grades such as YG6 and YG8 as examples, these cemented carbide balls are mainly composed of tungsten carbide (WC) and cobalt (Co) as a binder. They are sintered in a vacuum furnace using powder metallurgy technology, achieving a hardness of over 90.5 HRA and a density of 14.9 g/cm3. Their wear resistance is 50-100 times that of traditional steel balls, and they also possess excellent corrosion resistance and bending resistance.
Under the extreme operating conditions of brake pumps, cemented carbide balls must withstand high pressure (typically 10-20 MPa), high-frequency friction (thousands of reciprocating motions per minute), and chemical corrosion from brake fluid (containing mineral oil or synthetic esters) for extended periods. For example, in the application of deep-sea drilling pump valve balls, cemented carbide balls need to operate stably in sand-containing, high-pressure, and highly corrosive media. While brake pumps operate in environments free from seawater corrosion, they need to withstand more frequent opening and closing actions and temperature fluctuations (from -40℃ to 120℃). YG series alloys, by optimizing the cobalt content (e.g., YG6 contains 6% cobalt, YG8 contains 8% cobalt), achieve a balance between hardness and toughness, resisting abrasive wear from particles in brake fluid while preventing brittle fracture due to impact loads.
In the production process, cemented carbide balls undergo 12 processes, including cold isostatic pressing and vacuum sintering, to ensure a sphericity error ≤0.005mm and a surface roughness Ra ≤0.05μm. For the specific requirements of brake pumps, some manufacturers employ a sintering-hot isostatic pressing composite process to further eliminate internal porosity, achieving a density of over 99.9%, thereby extending service life.
Currently, cemented carbide balls are widely used in braking systems of passenger cars, commercial vehicles, and construction machinery, becoming an ideal solution to replace traditional steel balls and ceramic balls. With the increasing demand for lightweight and long-life braking systems in new energy vehicles, high-precision, non-standard customized cemented carbide balls are becoming an industry trend. Their sizes can be customized to cover the full spectrum of needs, from micro electric vehicles to heavy-duty trucks.
