Brake Disc Coating Stack to Prevent Flaking and Rust
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Solution Overview
Problem
Brake discs made of grey cast iron or steel suffer from excessive wear and surface oxidation, leading to rust formation, and existing protective coatings are prone to flaking and detachment due to the presence of free carbon in the coating, which compromises their adhesion and durability.
Innovation Solution
A method involving a nitrocarburized layer on the braking surface, followed by a base protective coating of chromium carbide and nickel-chromium, and a surface protective coating of tungsten carbide, iron, and aluminum, deposited using high-velocity techniques, to enhance adhesion and prevent flaking, while maintaining wear resistance and anti-corrosive properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a protective coating is applied on grey cast iron or steel discs, then wear resistance is improved, but the coating is subject to flaking and detachment
Solution Approach 1:
The patent applies a preliminary oxidation treatment to the grey cast iron or steel disc surface before coating deposition. This oxidation layer is formed in advance to create a suitable substrate that prevents carbon combustion during coating application, thereby eliminating the root cause of flaking and detachment while maintaining wear resistance
Solution Approach 2:
The patent introduces an oxidation layer as an intermediary between the metal disc substrate and the protective coating. This intermediate layer acts as a buffer that prevents direct interaction between free carbon in the coating and oxygen, eliminating micro-bubble formation and improving coating adhesion while preserving wear resistance
2Ease of manufacture
If free carbon is present in the protective coating, then the coating can be formed, but carbon combustion creates micro-bubbles that prevent adequate adhesion
Solution Approach 1:
The oxidation layer is formed preliminarily on the disc surface before coating deposition. This pre-formed layer serves as a protective barrier that prevents carbon combustion during the coating formation process, allowing the coating to be deposited without micro-bubble formation while maintaining adequate adhesion
Solution Approach 2:
The patent converts the potentially harmful effect of free carbon combustion into a beneficial process by controlling oxidation in advance. The preliminary oxidation creates a layer that actually protects against uncontrolled carbon combustion during coating application, transforming what would be a harmful reaction into a controlled, beneficial process
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 flaking and enhances wear resistance and anti-corrosive performance, maintaining the disc's integrity under environmental stresses and thermal shocks, with comparable tribological behavior to traditional discs without the nitrocarburized layer.
Implementation Method 1
A method involving a nitrocarburized layer on the braking surface
Implementation Method 2
deposited using high-velocity techniques
Data Source
AI summary
A method for making a brake disc may include the following steps: a) preparing a brake disc having a braking band provided with two opposite braking surfaces, (b) subjecting at least one of the braking surfaces to a working process adapted to increase the surface roughness thereof; c) nitrocarburizing the braking surface with increased surface roughness to obtain on the surface a nitrocarburized surface layer; (d) depositing on the nitrocarburized surface layer a material in particle form having: —Cr3C2 and NiCr, or —NiCr, Fe, Mo, Co, Mn and Al, which forms a base protective coating; and e) depositing on the base protective coating a material in particle form consisting of WC, Fe, Cr and Al, thus forming a surface protective coating of WC and Fe, Cr and Al.