Carbon Ceramic Brake Disc Intermediate Layer Design
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Solution Overview
Problem
Carbon-ceramic brake discs face thermal stress issues due to differing thermal expansion coefficients of their materials, leading to potential micro-cracks and failure, which existing methods can only mitigate within a limited temperature range.
Innovation Solution
A multi-layered carbon-ceramic brake disc production method involving a supporting body with long carbon fibers, a friction layer with short fibers, and an intermediate layer with coated fiber bundles, where the layers are processed with specific molding compounds and thermal treatments to adjust thermal expansion coefficients and reduce stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different materials are used for the supporting body and friction layer, then the mechanical and tribological properties are improved, but the thermal stress increases due to different thermal expansion coefficients
Solution Approach 1:
An intermediate layer is introduced between the supporting body and friction layer to act as a stress buffer. This intermediate layer has thermal expansion properties that are intermediate between the supporting body and friction layer, thereby reducing thermal stress concentration at the interfaces during cyclic thermal loading.
Solution Approach 2:
The patent employs a multi-layer composite structure where each layer is made of different ceramic materials optimized for its specific function. The supporting body uses high-strength ceramic, the friction layer uses wear-resistant ceramic, and the intermediate layer uses ceramic with intermediate thermal expansion properties, creating a composite structure that balances multiple requirements.
2Stress or pressure
If additives are used to adjust thermal expansion coefficients, then the thermal stress is reduced within a limited temperature range, but the adjustment is only effective for a limited temperature range
Solution Approach 1:
Different layers are assigned different material compositions and thermal expansion properties according to their specific functional requirements. The supporting body layer, friction layer, and intermediate layer each have locally optimized material properties, with the intermediate layer specifically designed to have intermediate thermal expansion characteristics to bridge the gap between the other two layers across a broad temperature range.
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 effectively reduces thermal stress and crack formation across a broader temperature range while maintaining mechanical, thermal, and tribological properties, enhancing the durability and reliability of the brake discs.
Implementation Method 1
the resulting green body being carbonized at a temperature of 750° C. to 1300° C. in the absence of oxidizing agents, with the Molding compounds contained organic binder is essentially converted to carbon
Implementation Method 2
subsequent conversion of at least part of the carbon in the carbonized green body by the action of silicon-containing carbide-forming elements to carbides of these elements, at a temperature of at least 10 K above the melting temperature of the element in question
Implementation Method 3
this coating containing carbon, silicon carbide and silicon being formed by thermal treatment of fiber bundles coated with a mixture of silicon powder and a carbonizable resin or a carbonizable pitch, at a temperature of 900 °C to 1700° C. with the exclusion of oxidizing agents
Data Source
AI summary
Carbon ceramic brake disk has a wearing body and rubbing layer which are separated by an intermediate layer whereby reinforcing fibers exhibits in form of fiber bundles. The fiber bundles are surrounded by a layer from silicon carbide, silicon and carbon by thermal treatment of the mixture from silicon powder and carbonized resin or carbonized pitch at a temperature of 900 degree Celsius to 1700 degree celsius under exclusion of oxidizer. An independent claim is also included for the method for production of the carbon ceramic brake disk.