One coating - four solutions

C4INOXit® is the world's first coating solution developed for brake discs that provide permanent corrosion protection (long-term corrosion protection) for the entire grey cast iron disc body or a hybrid disc. Long-term corrosion protection can also be realized only on partial surfaces of the brake disc (friction surface/ ventilation channel/ mounting surface/ disc pot), but can also protect other components of the friction couple (pad) or of the caliper.

Along with the long-term corrosion protection, the friction surface quality of the brake disc is optimized in such a way that

(1) a significant increase in service life,
(2) a significant reduction of wear of the break disc,
(3) in combination with the pad a significant reduction of the emitted fine dust of the friction couple as well as
(4) a positive influence on noise emission by optimizing the natural frequency and the damping factor of the brake disc are achieved.

C4INOXit® is applied to the carrier material (substrate) in a single coating process and thus forms an inseparable layer structure on the surface of the brake disc together with the carrier material. It can be expected that the layer structure resulting from C4INOXit®, e.g. in electric vehicles, will not be eroded by wear and/or corrosion over the lifetime of the vehicle.

The coating solution was developed especially for the price-sensitive industrial scale in the automotive and automotive supplier industry and is also suitable for applications in industrial plant construction.

C4INOXit® can be configured to be suitable for electromobility but also for applications with extremely high loads. C4INOXit® is available for 3 application areas:

Patent pending

Long-term corrosion protection and fine dust reduction for electric vehicles

Patent pending

Long-term corrosion protection and fine dust reduction for applications with higher load

Patent pending

Long term corrosion protection and fine dust reduction for high performance applications


Properties of the C4INOXit® coating from an engineering perspective (development status 07/2020)
  • One coating - four solutions:
  • Long-term corrosion protection (including ventilation channel / friction surface)
    (diffusion 0.15 / 0.3mm - friction surface soon 0.6mm)
  • Reduction of fine dust emission (50-70% in relation to the friction couple)
  • Service life increase (factor 2; surface hardness 600-950HV)
  • Noise reduction (noise index 3)
  • Industry specific low manufacturing costs (Asm. 350/30 internally ventilated / 0.5 Mio p.a.)
  • Expected manufacturing costs: 5.50 EUR / piece - Coating of friction surface / ventilation channel including machining post-processing and license fee
  • Expected cost savings gray cast iron: 1.30 EUR / piece (potential from mass savings of friction surface and connecting vanes in the ventilation channel)
  • One coating layer / one coating process
  • Complete (slipstream-free) coating of the ventilation channel
  • Permanently no corrosion on coated surfaces including the friction surface (E-vehicles can be expected for the entire service life)
  • Uniform diffusion on all coated surfaces
  • Homogeneous surface hardness over the entire friction surface
  • Reduction of natural frequency and damping factor - improvement of comfort
  • Can be combined with all industry standard brake pads (NAO/ECE)
  • Friction surface coating beyond the wear limit - exclusion of friction variances
  • Reduced setting on mounting surface
  • Potential for material reduction of the connecting vanes in the ventilation channel e0.25kg / piece - 350/30
  • Potential for reducing the total brake disc mass e1.0 kg / piece - 350/30 (corresponds to the reduction of the unsprung mass per brake disc)
  • C4INOXit® optimized machining process for finishing
  • Coating and coating process compatible with European environmental requirements
  • Perspective customizable colouring of the coating
  • Successful test stand results of relevant industrial tests on test stands of relevant brake disc suppliers and test institutes (AK Master Performance Test, AMS 130 Performance Test, Wear Test, Mechanical Strength Test, Performance Test, Crack Test, Fine Dust Test, Corrosion Endurance Test, Measurement of Damping Factor)

Brake disc with short term corrosion protection

Brake disc with C4INOXit®.

AKM performance test


Improvement in fading behavior

AMS130 - Test


Similar to grey cast iron disc

Thermal strength


Similar to grey cast iron disc

Wear behaviour


Significant reduction of brake disc and pad wear

Strength test


Similar to grey cast iron disc

Corrosion endurance run

Failure after one cycle

Four cycles without complaint

Parking brake test


Similar to grey cast iron disc

Properties of the C4INOXit® coating from the user's perspective
  • Permanent corrosion resistance of the coated brake discs - no rusting or rusting over the entire brake disc body - brake disc looks like new even after years
  • "Rusting" (Sticking Corrosion) of the brake pads and the resulting "breaking noise" when starting up is no longer given
  • Significant increase in service life and associated reduction in brake disc replacement intervals
  • Expectedly no more replacement of the brake discs of electric vehicles during the whole life of the vehicle necessary
  • No usage-related parameter deterioration of the coated brake disc compared to traditional brake discs can be detected by the user
  • Significantly less soiling of the vehicle rims due to a considerable reduction in brake dust particles as a result of higher surface quality on the friction surface
  • 50-70% lower fine dust emission (of the friction couple) compared to a standard brake disc due to improved surface quality of the friction surface (especially relevant for inner cities)
  • Significantly reduced noise generation / transmission of the brake disc due to the positive influence of the C4INOXit® coating on the natural frequency and damping factor of the brake disc
  • No rusting of the brake discs during transport, sea shipping or on the exhibition areas (foiling (masking of car wheels) for export is not necessary)


Long-term corrosion protection and fine dust reduction a challenge for the automotive industry and electric mobility

Electric vehicles use the electric motor for braking (recuperation), so that only 5% - 10% of the installed brake system for the friction brake (including the brake discs) are used in everyday life. 90% - 95% of the braking processes are realized by the electric motor. As a result, the brake discs remain in the vehicle much longer and problems with the corrosion of a grey cast iron brake disc inevitably arise.

Mechanical "freebraking" with the aim of "derusting" of the friction surface by the driver is generally no longer possible due to the built-in system control of electric vehicles, or "freebraking" installed by the automobile manufacturer and interval-based on the system side often leads to soiling of the brake pads and after a certain time affects the comfort behavior of the brake.

In the absence of an industrializable and cost-effective long-term corrosion protection for brake discs that ensures long-term corrosion resistance, brake discs in electric mobility today are replaced at fixed intervals in combination with system-side freebraking.

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