Brake Disc Nitride Coating for Uniform Depth and Corrosion Resistance
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Solution Overview
Problem
Brake discs made of gray cast iron face limitations in corrosion resistance and wear resistance due to shallow and uneven nitride layers, with graphite exposure leading to corrosion and rust issues.
Innovation Solution
A method involving thermal spraying of a pure iron powder coating onto the brake disc, followed by burnishing and nitriding to form a ferrite matrix structure, allowing for a deeper and more uniform nitride layer formation, including epsilon and gamma prime phases, with optional strengthening elements like Cr, Al, and Ti to enhance hardness and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nitriding is performed directly on the surface of gray cast iron, then corrosion resistance is improved, but the nitride layer depth is shallow and thickness is uneven due to inhibition by pearlite and graphite
Solution Approach 1:
The patent applies preliminary action by performing thermal spraying of pure iron powder onto the gray cast iron surface before nitriding. This creates a ferrite matrix structure that facilitates nitrogen diffusion, solving the problem of shallow and uneven nitride layers while maintaining corrosion resistance improvement.
Solution Approach 2:
The patent changes the material parameter of the surface layer from gray cast iron (with pearlite and graphite) to a sprayed layer of pure iron powder forming ferrite matrix structure. This parameter change enables deeper and more uniform nitrogen diffusion during subsequent nitriding, resolving the contradiction between corrosion resistance improvement and nitride layer quality.
2Reliability
If a nitride layer is formed on gray cast iron, then surface protection is improved, but graphite is exposed and acts as corrosion acceleration points
Solution Approach 1:
The patent applies local quality by creating a localized ferrite matrix structure through thermal spraying of pure iron powder on the gray cast iron surface. This localized modification ensures complete nitrogen diffusion and uniform nitride layer formation in the sprayed region, preventing graphite exposure and eliminating corrosion acceleration points while maintaining overall surface protection.
3Strength
If strengthening elements like Cr, Al, Ti, and V are added to the coating material, then wear resistance is improved through strengthened nitride formation, but manufacturing complexity increases
Solution Approach 1:
The patent changes the chemical composition parameter of the coating material by adding strengthening elements (Cr, Al, Ti, V) to the pure iron powder. This compositional change enables formation of strengthened nitrides during nitriding, improving wear resistance. The manufacturing complexity increase is minimal as it only requires adding these elements to the spray material.
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 effectively prevents primary corrosion, improves corrosion and wear resistance, and ensures a uniform nitride layer depth, enhancing the overall performance and durability of the brake disc.
Implementation Method 1
thermal spraying a coating material including pure iron powder and other unavoidable impurities onto the surface of the disc base material
Implementation Method 2
a coating layer formed on a surface of the disc base material and including a nitride produced as nitrogen is diffused into a ferrite matrix structure
Implementation Method 3
nitriding the burnished sprayed layer
Data Source
AI summary
The present disclosure relates a brake disc and a method of manufacturing the same, in which the depth of the coating layer containing a nitride is adjustable and corrosion resistance and wear resistance can be improved. A brake disc according to an embodiment of the present disclosure includes: a disc base material made of gray cast iron; and a coating layer formed on a surface of the disc base material and including a nitride produced as nitrogen is diffused into a ferrite matrix structure.