Friction Disc Production via Silicon Carbide Matrix and Carbonized Support
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Solution Overview
Problem
Existing methods for producing friction discs with fiber-reinforced ceramic materials often result in defects such as burn-outs and uneven surfaces due to fiber exposure, leading to increased wear and unacceptable stress-relief structures, especially when using longer fibers or no fibers in the friction layer.
Innovation Solution
A method involving a carbonized porous carbon body reinforced with carbon fibers, combined with a supporting body in the CFRP or CSiC state, using a mixture with a high mass fraction of silicon carbide powder and a carbonizable binder, followed by pressing and siliconization to form a friction disc with improved tribological properties and reduced crack patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mass fraction of fibers or fiber bundles in the friction layer is increased to improve tribological properties, then friction performance is improved, but fiber burn-out occurs during operation leading to defects and increased wear
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating silicon carbide powder (50-95% by mass) and silicon powder (5-20% by mass) into the friction layer mixture, while reducing fiber content to 0.1-10% by mass. The silicon carbide reacts with carbon during pyrolysis to form a protective matrix that prevents fiber burn-out while maintaining friction performance.
Solution Approach 2:
The patent creates a composite friction layer material combining carbonizable binder, silicon carbide powder, silicon powder, and small amounts of carbon fibers. This composite structure provides both tribological performance and protection against fiber burn-out through the silicon carbide-rich matrix formed during processing.
2Object-affected harmful factors
If the mass fraction of fibers or fiber bundles is reduced to prevent burn-out, then fiber burn-out is reduced, but the carbonized preliminary body develops large cracks during pyrolysis
Solution Approach 1:
The patent modifies the chemical composition by adding silicon carbide powder and silicon powder, which during pyrolysis form a flexible matrix that accommodates shrinkage stresses. The silicon carbide reacts with carbon to form a graded structure that reduces thermal stress concentration, preventing large cracks while maintaining structural integrity.
Solution Approach 2:
The patent utilizes the porous structure formed during pyrolysis of the carbonizable binder, which is then infiltrated by silicon and silicon carbide. This porous-to-dense transformation creates a graded structure that absorbs shrinkage stresses and prevents large crack formation during the carbonization process.
3Manufacturing precision
If traditional production methods with multiple steps are used to achieve defect-free friction layers, then manufacturing precision is improved, but production time and complexity increase
Solution Approach 1:
The patent combines multiple functions into a single friction layer composition: the carbonizable binder provides structural framework, silicon carbide powder provides wear resistance and prevents fiber burn-out, silicon powder enhances reaction with carbon during pyrolysis, and minimal fibers provide reinforcement. This unified approach eliminates the need for separate friction layer application and infiltration steps.
Solution Approach 2:
The patent performs preliminary mixing of all components (carbonizable binder, silicon carbide powder, silicon powder, and fibers) before molding and pyrolysis. This pre-mixing ensures homogeneous distribution of protective silicon carbide throughout the friction layer, preventing defects during subsequent processing steps.
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 method produces friction discs with enhanced resistance to fiber burn-out and fine crack patterns, minimizing defects and wear, while reducing the number of production steps and requiring only single siliconization for optimal performance.
Implementation Method 1
which at least partially reacts with at least part of the carbon to form silicon carbide
Implementation Method 2
The carbonized preliminary body for the friction layer, which is present as a porous carbon body
Data Source
AI summary
The invention relates to a method for producing friction discs from fiber-reinforced ceramic materials, in which a friction layer pre-body is first produced in the form of a separately manufactured cylindrical-ring-shaped disc from a mixture of silicon carbide powder, silicon powder, a carbonizable binder and optionally a small proportion of short carbon fibers by pressing into a cylindrical-ring-shaped disc, hardening and carbonizing, the friction layer pre-body is then combined with a support body which is either in the CFRP state or in the CSiC state, and the combination is optionally infiltrated with liquid silicon under reduced pressure after further carbonizing.