Light Metal Brake Disc with Oxide Coating for Wear Resistance

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Solution Overview

Problem

Conventional brake discs face issues with high temperature resistance, wear resistance, and manufacturing costs, as well as thermal stress leading to oxidation and cracking due to differing material expansion coefficients.

Innovation Solution

A brake disc made from a light metal with a hard anodized or plasma-electrolytic oxidation (PEO) oxide layer, which provides high wear resistance and temperature resilience, and can be produced inexpensively using methods like casting, 3D printing, or laser welding, with a heat-conducting element for efficient heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a hard metal coating is applied to a gray cast iron brake disc to improve wear resistance, then wear resistance is improved, but cracks can occur in the coating under high temperature loads due to different coefficients of expansion

Engineering Contradiction:
Improvewear resistanceVSAvoidcoating integrity
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention changes the material parameter by using a light metal base (aluminum, magnesium, or titanium) instead of gray cast iron, and applies an oxide layer coating that is chemically bonded to the base material. This eliminates the coefficient of expansion mismatch problem that causes cracking in conventional hard metal coatings on cast iron, while maintaining high wear resistance through the oxide layer.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite structure consisting of a light metal base material (aluminum, magnesium, or titanium) combined with an oxide layer coating. This composite material system provides both the wear resistance of the oxide layer and the structural properties of the light metal, while avoiding the interfacial cracking problems of conventional coatings through chemical bonding between the layers.

Inventive Principle:
Principle #40Composite materials

2Strength

If conventional coating methods are used to provide wear resistance, then wear reduction is achieved, but the brake disc is thermally stressed leading to oxidation of the wear-reducing layer

Engineering Contradiction:
Improvewear resistanceVSAvoidoxidation
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The invention uses self-service by allowing the light metal base material to form its own oxide layer coating through controlled oxidation processes (anodizing or plasma electrolytic oxidation). This oxide layer is chemically bonded to the base material and is inherently resistant to further oxidation, eliminating the thermal stress and oxidation problems associated with conventional coating methods that require external coating materials.

Inventive Principle:
Principle #25Self-service

3Temperature

If gray cast iron is used for high temperature resistance, then temperature resistance is improved, but manufacturing costs and weight increase

Engineering Contradiction:
Improvetemperature resistanceVSAvoidbrake disc weight
Core Design Contradiction:
TemperatureVSWeight of moving object

Solution Approach 1:

The invention changes the base material from heavy gray cast iron to lightweight metals (aluminum, magnesium, or titanium) while maintaining temperature resistance through the protective oxide layer coating. This parameter change reduces the weight of the brake disc by approximately 50% compared to conventional cast iron discs, while the oxide layer ensures high temperature resistance and wear resistance are maintained.

Inventive Principle:
Principle #35Parameter changes

4Temperature

If gray cast iron is used for high temperature resistance, then temperature resistance is improved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvetemperature resistanceVSAvoidmanufacturing cost
Core Design Contradiction:
TemperatureVSEase of manufacture

Solution Approach 1:

The invention changes the base material from gray cast iron to light metals (aluminum, magnesium, or titanium) and uses surface treatment processes (anodizing or plasma electrolytic oxidation) to achieve temperature resistance. This approach simplifies manufacturing by eliminating the need for expensive hard metal coating applications and intermediate layers required for cast iron, while reducing overall production costs through more straightforward processing steps.

Inventive Principle:
Principle #35Parameter changes

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 offers a cost-effective, durable brake disc with improved heat management and reduced wear, maintaining strength and wear resistance even at high temperatures, while minimizing manufacturing complexity and thermal stress issues.

Implementation Method 1

An oxide layer, in particular a hard anodized layer, is produced by hard anodizing, which is also referred to as hard anodizing or hard coating, or by plasma-electrolytic oxidation (PEO). This involves electrolytic oxidation of the base plate, which creates an abrasion-resistant layer on the base plate.

Methodology Applied
Scientific EffectElectrolytic oxidation: Oxidation

Implementation Method 2

An oxide layer, in particular a hard anodized layer, is produced by hard anodizing, which is also referred to as hard anodizing or hard coating, or by plasma-electrolytic oxidation (PEO).

Methodology Applied
Scientific EffectPlasma-electrolytic oxidation: Plasma

Data Source

PatentEP3455517B1Brake disc and method for producing same
Publication Date: 2020.09.09 ROBERT BOSCH GMBH
  • EP3455517B1 patent drawingFigure 1~2
  • EP3455517B1 patent drawingFigure 3
  • EP3455517B1 patent drawingFigure 4

AI summary

The invention relates to a brake disc (1), in particular for a motor vehicle, comprising a base disc (2) of a first material and a wear-reducing coating (8,9) of a second material. According to the invention, it is provided that the first material is a lightweight metal and the second material is an oxide layer (8,9).