Brake Pads Mineral Fibers
Mineral fibers, a category of inorganic fibrous materials derived from natural minerals or industrial by-products, serve as essential reinforcing and friction-modifying components in brake pad formulations, balancing mechanical strength, cost-effectiveness, and environmental compliance for mainstream automotive applications. Their diverse compositions and structural traits make them a versatile alternative to asbestos and synthetic organic fibers in semi-metallic and ceramic friction composites.
Classification and Core Material Traits
Key Variants and Performance Differentiation
Common mineral fibers in brake pads include wollastonite, basalt fiber, and sepiolite, each with distinct properties: wollastonite (calcium silicate) offers high rigidity and thermal stability (up to 800°C), while basalt fiber, processed from volcanic rock, delivers superior tensile strength (1.5-3GPa) and chemical inertness. Sepiolite, a magnesium silicate fiber, excels in moisture absorption and dispersion, making it suitable for low-noise formulations.
Unlike glass fibers, mineral fibers exhibit lower brittleness and reduced rotor abrasion, though their thermal conductivity (0.15-0.3W/(m·K)) is generally inferior to metallic fillers. Their non-combustible nature and resistance to resin binder degradation under high temperatures further enhance brake pad durability.
Formulation Application and Synergistic Design
Loading Range and Application Tailoring
In brake pad formulations, mineral fibers are typically incorporated at 10%-20% by weight, with dosage adjusted by variant: wollastonite, due to its high hardness, is limited to 12%-15% to avoid excessive rotor wear, while basalt fiber, with better toughness, can be loaded up to 18% for heavy-duty vehicle pads. Finer fibers (1-3mm length) improve friction uniformity, while coarser variants (3-5mm) reinforce structural integrity.
Compatibility with Other Friction Components
Mineral fibers are often blended with graphite, copper chips, and phenolic resins to optimize composite performance. They complement graphite’s lubricity by enhancing shear strength, while copper chips offset their low thermal conductivity. Annat Brake Pads Chemical Materials customizes mineral fiber blends for regional markets, balancing cost, performance, and environmental regulations.
Processing Control and Quality Standards
Preserving fiber aspect ratio is critical—excessive mechanical mixing can fracture fibers, reducing reinforcing efficiency. Manufacturers adopt low-shear mixing processes, pre-treating fibers with silane coupling agents to improve interfacial adhesion with resin binders and prevent agglomeration.
Quality criteria demand mineral purity ≥98%, with impurities such as iron oxides and quartz limited to ≤1.5%—these contaminants increase abrasiveness and compromise friction stability. Moisture content is controlled below 0.8% to avoid curing defects during hot-press molding, as hydrated fibers may release vapor and form internal voids.
Performance Validation and Industry Trends
Dynamometer testing confirms that mineral fiber-reinforced brake pads exhibit 12%-18% higher wear resistance than asbestos-free organic pads, with friction coefficient variation within ±0.04 under simulated urban and highway driving cycles. They also reduce braking noise by dampening vibration at the friction interface.
Driven by eco-friendly trends and asbestos bans, demand for high-purity mineral fibers is rising, with manufacturers developing surface-modified variants to enhance resin compatibility. A common production challenge is fiber dispersion uniformity, addressed via precision air classification. A typical typo in technical documents is misspelling "wollastonite" as "wollastonite," a subtle error that may confuse material sourcing specifications.