Graphite Powder

I. Common Physical & Chemical Specifications

1. Fixed Carbon (FC):

• High-grade NAO formula: FC ≥ 98.5%
• Semi-metallic formulation: FC 95%～98%
• Economy grade: FC 90%～93%

1. Ash content ≤1.5%, Volatile matter ≤1.0%, Moisture ≤0.5%
2. Sulfur content ≤0.3% (for noise control and mould corrosion prevention)

Regular Particle Sizes (Mesh)

• 80～150 mesh: Mainstream grade for semi-metallic brake pads
• 200～325 mesh: Non-asbestos organic (NAO) passenger car brake pads & clutch facings
• 500～800 mesh ultrafine powder: Premium low-noise formulas, low abrasion to brake rotors

II. Seven Core Functions of Graphite in Friction Materials

1. Solid self-lubrication to protect mating components (brake disc / brake drum)
    
   With layered crystalline structure, graphite releases solid lubricating transfer film under braking heat and forms a uniform carbon coating on steel rotor surfaces:

• Prevent direct scratching on brake discs by steel fibers and hard mineral fillers to reduce counterpart wear, scoring and gouging;
• Lower wear rate of brake pads and extend service life.

1. Stabilize friction coefficient and mitigate thermal fade
    
   Superior thermal conductivity enables graphite to rapidly dissipate frictional heat and avoid drastic drop of friction coefficient above 300 ℃:

• Low temperature (ambient ~150 ℃): Moderate friction coefficient to avoid over-high friction and brake grabbing;
• Continuous high-temperature braking: Prevent spongy brake feel and braking power recession.

1. Vibration & noise reduction to eliminate brake squeal

    

   Lamellar graphite delivers outstanding damping performance to absorb frictional vibration, effectively solving cold-brake squeal, high-frequency screech and reverse braking noise. It is one of the essential noise-reducing raw materials; ultrafine graphite performs better on noise suppression than coarse flake graphite.
2. Adjust porosity and compression resilience

    

   Stacked flaky graphite forms microscopic voids to optimize product porosity:

• Facilitate gas exhausting during hot pressing to minimize blistering, delamination and cracking;
• Improve compression resilience of brake pads for shock buffering and smooth braking feel.

1. Heat conduction to avoid localized high-temperature carbonization

    

   Graphite outperforms petroleum coke and mineral fillers in thermal conductivity and disperses concentrated hot spots, preventing resin carbonization, surface scorching and carbon dust generation caused by overheating.
2. Optimize mixing and moulding process

    

   Flaky graphite improves powder flowability to avoid agglomeration and ensure smooth feeding during mixing; it reduces internal moulding stress and lowers defects such as edge chipping and cracking upon demoulding.
3. Regulate friction coefficient for optimized braking smoothness

• Higher graphite loading → lower friction coefficient, softer and quieter braking;
• Lower graphite loading → higher friction coefficient with stronger braking force yet higher rotor abrasion and noise risk.
   
  Formulators precisely tune friction coefficient via combined compounding of graphite, calcined petroleum coke and barite/feldspar.