What specific effects do the performance parameters of friction materials have on braking performance?
I. Core Performance Parameters → Specific Effects on Braking Performance
1. Friction Coefficient
Direct impacts: Braking force magnitude, braking distance, braking response speed
Higher friction coefficient → Greater braking torque under the same braking force → Shorter braking distance and more sensitive braking.
Too low coefficient → Soft braking, extended braking distance, high risk of rear-end collisions at high speed/under heavy load.
Large coefficient fluctuation → Inconsistent braking feel, driver fatigue, and easy loss of control.
2. High-temperature Resistance
Direct impact: Braking performance retention after continuous braking
Regular semi-metallic (500℃): Suitable for highways/national roads, stable for daily long-distance driving, but not for long downhill sections.
Copper-based sintered (800℃): Maintains braking capability at high temperatures under heavy load/long downhill mountain roads, avoiding brake fade.
3. Heat Fade Rate
Direct impact: Whether brakes fail after continuous use
Heat fade rate = Degree of friction coefficient reduction at high temperatures.
Fade rate ≤10% (copper-based sintered): Almost no performance degradation during long downhill braking, fundamentally preventing brake failure.
Excessive fade rate: Braking becomes increasingly weak after continuous use, eventually leading to complete loss of stopping power.
4. Friction Coefficient Stability (Fluctuation within Temperature Range)
Direct impact: Braking linearity, no deviation, no skidding
Stable coefficient within temperature range: Braking force changes linearly with pedal input, no nose dive, deviation, or sideslip.
Large fluctuation: Significant difference in braking force between cold and hot conditions, prone to braking deviation and difficult steering control.
5. Shear Strength
Direct impact: Whether the brake pad will detach or crack during braking
Insufficient shear strength: Separation of friction material from the backing plate during hard braking/high temperature → Sudden brake failure, extremely dangerous.
National standard ≥3.5MPa, European standard ≥4.0MPa: Ensures no detachment under heavy load and high-frequency braking.
6. Low-temperature Performance (No attenuation at -40℃)
Direct impact: Cold-start braking reliability in frigid regions
Ordinary materials harden at low temperatures with sharp coefficient drop → Brake failure when starting cold.
Low-temperature enhanced NAO: Immediate and responsive braking in extreme cold, suitable for cold-chain/frigid region transportation.
7. Salt Spray Corrosion Resistance
Direct impact: Long-term braking precision, no jamming, no uneven wear
Rusting of backing plate/components in high-salt environments → Poor brake return, dragging, uneven wear, and unstable braking.
Salt spray resistance ≥500h: No rust on backing plate, stable braking clearance, and consistent braking performance over long-term use.
8. Wear Uniformity
Direct impact: Service life, performance consistency, maintenance cost
Uniform wear: Stable braking performance throughout service life, no early failure, abnormal noise, or vibration.
Uneven/abnormal wear: Brake judder, damage to brake discs/drums, and sharply increased failure rate in later use.
