Copper-Ferrochrome Sintered Brake Material for High-Speed Rail
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Solution Overview
Problem
Conventional sintered friction materials for high-speed railway vehicles face challenges in maintaining a high friction coefficient at speeds beyond 300 km/h due to thermal issues and wear resistance, with existing materials experiencing sudden temperature rises and oxidation, leading to unstable adhesion and increased wear.
Innovation Solution
A sintered friction material using copper as a base material, combined with 1-20% by volume ferrochrome (FeCr) and 5-20% by volume metal oxides like MgO, ZrO2, and Al2O3, along with 30-60% by volume lubricants, optimized to prevent oxidation and maintain high friction coefficients through improved thermal conductivity and abrasive properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If iron powder and stainless steel powder are used in combination to generate voids for abrasive function, then friction coefficient is ensured, but wear resistance deteriorates and thermal conductivity is insufficient causing sudden temperature rise
Solution Approach 1:
The patent changes the chemical composition parameters by replacing conventional iron powder and stainless steel powder with ferrochrome powder containing 60-80 mass% Cr. This parameter change transforms the material properties to achieve both high friction coefficient and excellent wear resistance without the temperature rise issues associated with conventional iron-based materials.
Solution Approach 2:
The patent creates a composite friction material combining copper matrix with ferrochrome powder and specific lubricants. This composite structure leverages the high thermal conductivity of copper and the superior wear resistance and friction properties of ferrochrome, resolving the contradiction between friction performance and wear resistance.
2Force
If iron-based alloy is used as base material to improve friction coefficient, then adhesion is enhanced, but thermal conductivity deteriorates causing sudden temperature rise during deceleration
Solution Approach 1:
The patent employs a composite material system with copper as the base matrix and ferrochrome as the friction modifier. This composite structure maintains the high thermal conductivity of copper to prevent temperature rise while incorporating ferrochrome to provide the necessary adhesion force for high friction coefficient.
Solution Approach 2:
The patent changes the base material from iron-based alloy to copper-based material, fundamentally altering the thermal conductivity parameter. This parameter change enables effective heat dissipation during high-speed deceleration while maintaining friction performance through the addition of ferrochrome.
3Force
If Fe is added as friction modifier to react with Fe in counterpart material for adhesion, then friction coefficient is improved, but oxidation occurs at high temperature beyond 1,000°C causing unstable friction performance
Solution Approach 1:
The patent changes the chemical composition of the friction modifier from pure iron to ferrochrome containing 60-80 mass% Cr. This parameter change provides oxidation resistance at high temperatures while maintaining the ability to react with counterpart material Fe for adhesion, ensuring stable friction coefficient even when surface temperature exceeds 1,000°C.
Solution Approach 2:
The chromium in ferrochrome forms a protective oxide layer that acts as a barrier, preventing further oxidation of the underlying material. This protective mechanism maintains the structural integrity and friction properties of the material even under extreme thermal conditions.
4Temperature
If copper is used as base material for high thermal conductivity, then temperature rise is prevented, but wear resistance and friction coefficient deteriorate compared to iron-based materials
Solution Approach 1:
The patent creates a composite material combining copper matrix with ferrochrome powder (60-80 mass% Cr). This composite structure leverages the high thermal conductivity of copper for temperature control while incorporating ferrochrome to provide the necessary friction coefficient and wear resistance, achieving a balance between thermal management and friction performance.
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 effectively maintains a high friction coefficient beyond 300 km/h while reducing wear and preventing oxidation, ensuring stable performance and extended durability of the friction material.
Implementation Method 1
since copper having excellent thermal conductivity is used as a base material, temperature would be prevented from rising suddenly during deceleration
Implementation Method 2
the Fe added to the copper-based sintered friction material reacts with Fe contained in a counterpart material so that the both can be adhered with each other to obtain a high friction coefficient
Implementation Method 3
due to friction heat generated during deceleration
Data Source
Figure 1
AI summary
The purpose of the present invention is to provide a sintered friction material for high speed railway vehicles, which is capable of stably maintaining high friction coefficient even in a high-speed range exceeding 300 km/h. The sintered friction material for high speed railway vehicles according to the present invention contains Cu as a base material, FeCr by 1-20 vol%, a metal oxide by 5-20 vol%, and a lubricant by 30-60 vol%.