Laser-Alloyed Gray Cast Iron Brake Disc for Low-Wear Braking

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Solution Overview

Problem

Friction brakes for motor vehicles experience significant wear and corrosion due to abrasion between the brake pad and disc, leading to brake dust and reduced performance, which existing wear protection methods have not adequately addressed.

Innovation Solution

A laser-alloyed edge layer is applied to a gray cast iron brake disc using additives like chromium carbide, niobium carbide, and elemental chromium, which forms a cohesive, corrosion-resistant wear protection layer with enhanced abrasion resistance through melting and alloying, followed by rapid solidification and potential additional hardening processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a wear protection layer is applied to the friction brake body, then wear and corrosion resistance is improved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvewear and corrosion resistanceVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functions into a single laser processing step: melting the base material, mixing with additives, and forming the wear protection layer all occur in one continuous laser alloying process, eliminating separate coating and bonding steps

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces traditional mechanical coating methods (such as plasma spraying or thermal spraying followed by bonding) with a laser-based metallurgical process that directly fuses the wear protection layer into the base material through laser alloying

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If traditional coating methods are used to protect the brake disc, then wear resistance is improved, but brake dust emissions increase

Engineering Contradiction:
Improvewear resistanceVSAvoidbrake dust emissions
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent creates a composite material structure by incorporating ceramic particles (such as aluminum oxide, silicon carbide, or boron carbide) into the metal matrix during laser alloying, forming a metallurgically bonded composite that reduces wear and brake dust

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent converts the harmful effect of friction and abrasion into a beneficial process by using the laser's thermal energy to melt and fuse materials, creating a wear-resistant surface that actually reduces future abrasion and brake dust generation during normal brake operation

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If the surface layer is melted and alloyed with additives, then abrasion resistance is improved, but energy consumption increases

Engineering Contradiction:
Improveabrasion resistanceVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies laser energy locally only to the surface layer where wear protection is needed, rather than heating the entire brake disc, concentrating energy input precisely where it is required to melt and alloy the surface

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The laser processing is applied periodically only during manufacturing, not during continuous brake operation, and the rapid solidification of the melted layer occurs quickly, limiting the duration of high energy input

Inventive Principle:
Principle #19Periodic action

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 and corrosion on the friction brake body, minimizing brake dust emissions and providing improved abrasion and corrosion resistance while maintaining cost-effectiveness and environmental benefits.

Implementation Method 1

The surface layer of the base body is melted into a melt using laser radiation

Methodology Applied
Scientific EffectLaser irradiation melting: Laser

Implementation Method 2

The additive is thus added to the molten material of the base body and is distributed there as a result of convective mixing of the melt pool

Methodology Applied
Scientific EffectConvective mixing: Convection

Implementation Method 3

a sufficiently rapid solidification and cooling in the surface layer during laser alloying or laser dispersing, so that a martensitic basic structure forms in the surface layer immediately after laser alloying or laser dispersing

Methodology Applied
Scientific EffectRapid solidification: Freezing

Implementation Method 4

the chromium remains substitutionally dissolved in the iron matrix of the laser-alloyed surface layer and thus, in the presence of oxygen, forms a passive layer on the surface that offers effective corrosion protection

Methodology Applied
Scientific EffectOxidation: Oxidation

Data Source

PatentEP3973205B1Method for producing a friction brake body for a friction brake
Publication Date: 2024.02.28 ROBERT BOSCH GMBH
  • EP3973205B1 patent drawingFigure 1
  • EP3973205B1 patent drawingFigure 2~3

AI summary

The invention relates to a friction brake body (1) for a friction brake of a motor vehicle, in particular a brake disc (2), wherein the friction brake body (1) comprises a base body (3) made from gray cast iron, and at least one wear resistant layer (5) formed at least in areas on the base body (5). According to the invention, the wear resistant layer (5) is a laser alloyed or laser dispersed edge layer (6) of the base body (3) and comprises at least one additional material (9).