Ferritic Nitrocarburized Brake Rotor Coating for Wear and Corrosion
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Solution Overview
Problem
Friction brake components, such as brake rotors and drums, face rapid wear and corrosion due to graphite flakes at the friction surface, which reduce their effectiveness and lifespan, as graphite acts as initiation sites for corrosion and lowers the coefficient of friction.
Innovation Solution
A ferritically nitrocarburized rotational member with a compound zone at the friction surface, where the exposed surface contains from about 0 to 14 percent graphite, forming an oxide layer and iron nitride layer to resist corrosion and wear, and a method to remove graphite flakes before nitrocarburization to prevent masking and corrosion initiation sites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If graphite flakes are present at the friction surface, then the brake component is easier to manufacture, but wear resistance and corrosion resistance deteriorate
Solution Approach 1:
The patent applies preliminary action by removing graphite flakes from the friction surface before applying the ferritic nitrocarburized coating. This pre-treatment step ensures that the coating adheres properly to the substrate without interference from graphite flakes, which would otherwise prevent effective coating formation and lead to poor wear and corrosion resistance. The removal of graphite flakes creates a clean surface ready for the protective coating process.
Solution Approach 2:
The patent applies the extraction principle by removing the harmful graphite flakes from the friction surface. Instead of working with the graphite-containing surface, the process extracts these problematic particles through cleaning or blasting operations before coating application. This eliminates the root cause of poor coating adhesion and prevents graphite from acting as corrosion initiation sites under the coating.
2Ease of manufacture
If graphite flakes are present at the friction surface, then the brake component can be produced using conventional methods, but corrosion resistance deteriorates
Solution Approach 1:
The patent applies preliminary action by removing graphite flakes from the friction surface before applying the ferritic nitrocarburized coating. This pre-treatment step ensures that the coating forms a continuous, adherent protective layer without gaps or weak points where corrosion could initiate. The clean surface allows the coating to serve as an effective barrier against corrosive environments.
Solution Approach 2:
The patent converts the harmful effect of graphite flakes into a benefit by using their removal as the foundation for creating a superior protective coating system. The graphite removal process, while eliminating a harmful element, simultaneously prepares the surface for optimal coating adhesion, transforming a defective surface into an ideal substrate for corrosion protection.
3Ease of manufacture
If graphite flakes are present at the friction surface, then the manufacturing process is simpler, but the coefficient of friction decreases
Solution Approach 1:
The patent applies preliminary action by removing graphite flakes from the friction surface before coating application. This ensures that the ferritic nitrocarburized coating forms a uniform, adherent layer that provides consistent friction characteristics. The absence of graphite flakes prevents localized variations in friction coefficient and ensures reliable brake performance throughout the service life of the component.
4Ease of manufacture
If graphite flakes are present at the friction surface, then conventional manufacturing can be used, but wear of friction material increases
Solution Approach 1:
The patent applies preliminary action by removing graphite flakes from the friction surface before applying the ferritic nitrocarburized coating. This pre-treatment creates an optimal surface for coating adhesion, ensuring that the protective layer remains intact during brake operation. The intact coating prevents direct contact between the friction material and substrate, significantly reducing wear of the friction material by eliminating abrasive graphite particles.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly reduces wear of the friction material and rotational member, maintaining a high coefficient of friction and improving corrosion resistance, with wear rates less than 0.4 mm per 1000 stops at 350°C and a friction coefficient of at least 0.32, while preventing premature corrosion.
Implementation Method 1
A ferritically nitrocarburized rotational member of a vehicle brake has a rotational member, including a friction surface configured for braking engagement with a corresponding friction material. A compound zone is disposed at the friction surface.
Implementation Method 2
forming an oxide layer and iron nitride layer to resist corrosion and wear
Implementation Method 3
a friction surface configured for braking engagement with a corresponding friction material
Data Source
AI summary
A ferritically nitrocarburized rotational member of a vehicle brake is disclosed, including a rotational member having a friction surface configured for braking engagement with a corresponding friction material. A compound zone is disposed at the friction surface. An exposed surface of the compound zone is exposed to an atmosphere. The area of the exposed surface includes from about 0 percent to about 14 percent graphite.