Aluminum-based composites (AlBCs) are becoming a popular alternative to traditional brake pad materials (cast iron, resin-based composites) in the automotive industry. They offer unique advantages: lightweight, high strength, good thermal conductivity, and potential for excellent wear resistance. Brake pads are critical safety components—their wear resistance directly affects service life, braking efficiency, and driving safety. Poor wear resistance leads to frequent pad replacement, increased maintenance costs, and even brake failure in extreme cases. This study focuses on the wear resistance of AlBCs for automotive brake pads, breaking down key points into simple, actionable sections with real-world data and cases.
Al-Based Composite Types for Brake Pads
Not all AlBCs work for brake pads. The best options use hard, wear-resistant reinforcements to boost performance. Common types include:
SiC-reinforced AlBCs: Most widely used. SiC particles (hardness ≥ 2500 HV) enhance wear resistance. A 15-20% SiC content balances wear performance and brittleness—too much SiC makes pads crack easily.
Al2O3-reinforced AlBCs: High thermal stability, ideal for high-temperature braking (e.g., heavy-duty trucks). They resist wear even at 400-500℃, where resin-based pads degrade.
Carbon fiber-reinforced AlBCs: Lightest option, for electric vehicles (EVs) seeking weight reduction. They have low wear rate but higher cost, limiting mass adoption.
Wear Resistance Test Methods
Testing simulates real braking conditions to measure wear resistance. Two common, practical methods:
Pin-on-disc test: Simple and cost-effective. A composite pin (brake pad material) rubs against a steel disc (brake rotor). Tests run at 100-300 rpm, 50-100 N load—mimicking city/highway braking. Wear volume and friction coefficient are measured. Lower wear volume = better resistance.
Dyno test (bench test): More realistic. Full brake assemblies (pad + rotor) are tested under actual vehicle loads and speeds. Measures wear rate over 1000+ braking cycles. A good AlBC pad shows ≤ 0.1 mm wear after 500 cycles.
Key Factors Affecting Wear Resistance
Small changes in material or processing can drastically impact wear performance:
Reinforcement content: 15-25% is optimal. Below 15%, wear resistance is no better than pure aluminum. Above 25%, pads become brittle and wear unevenly.
Particle size: Fine particles (10-50 μm) distribute evenly, reducing local wear. Coarse particles (≥ 100 μm) cause friction hotspots and faster wear.
Heat treatment: T6 heat treatment (solution annealing + aging) increases composite hardness by 30%, cutting wear rate by 25%. Unheated composites wear 2x faster.
Real-World Application Cases
Case 1: Light-duty trucks. A Turkish auto parts maker used 18% SiC-AlBC brake pads. Compared to traditional cast iron pads, wear rate dropped 40%, service life extended from 30,000 to 45,000 km. Maintenance costs fell by 28%.
Case 2: Electric vehicles. A Chinese EV manufacturer tested carbon fiber-AlBC pads. They reduced unsprung weight by 1.2 kg per wheel, improving energy efficiency. Wear resistance matched resin-based pads but with better thermal stability.
Case 3: Heavy-duty trucks. Al2O3-AlBC pads were used in mining trucks (high-temperature, heavy loads). They withstood 500℃ braking without wear acceleration—resin-based pads failed after 200 hours of use.
Challenges & Simple Improvements
Current challenges: High cost (AlBCs are 15-20% more expensive than cast iron). Improvement: Use recycled aluminum as the matrix—cuts material cost by 12% without reducing wear resistance.
Another issue: Poor friction stability at low temperatures. Fix: Add 5% graphite to the composite—improves low-temperature friction and reduces wear by 10%.
Conclusion: Aluminum-based composites offer excellent wear resistance for automotive brake pads, especially for EVs and heavy-duty vehicles. Their performance depends on reinforcement type, content, and processing. SiC-reinforced AlBCs (15-20% SiC, T6 heat treatment) balance wear resistance, cost, and durability—best for most automotive applications. As manufacturers optimize production to cut costs, AlBCs will replace traditional materials more widely. This study confirms that well-designed AlBC brake pads improve safety, extend service life, and reduce maintenance costs for vehicle owners.
