Low-Copper Friction Material Composition for Stable Brake Friction
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Solution Overview
Problem
Conventional friction materials without copper face challenges in maintaining a stable friction coefficient during high-speed and high-temperature braking, as well as after exposure to high humidity, which can lead to sudden braking or brake squealing, especially in controlled braking systems.
Innovation Solution
A friction material composition containing a silicone-containing phenol resin as a binder, a specific ratio of α-alumina and γ-alumina, 20-35% titanate salt, 3-7% graphite with a median diameter of 1-30 μm, and antimony trisulfide, which maintains the friction coefficient during high-speed and high-temperature braking while preventing excessive increase after high humidity exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If copper is removed from friction material composition, then environmental pollution is reduced, but thermal conductivity and friction coefficient stability deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters by removing copper and introducing alternative materials (graphite, metal fibers, organic fillers) with different properties. This resolves the contradiction by achieving low copper content (≤5% or ≤0.5%) while maintaining friction performance through parameter optimization
Solution Approach 2:
The patent uses composite materials combining multiple components (graphite, metal fibers, organic fillers, binders) to replace copper's functions. The composite structure provides both thermal management and friction stability without relying on copper, thus reducing pollution while maintaining reliability
2Object-affected harmful factors
If conventional NAO materials are used without copper, then environmental compliance is improved, but friction coefficient increases excessively after high humidity exposure
Solution Approach 1:
The patent introduces intermediary substances (graphite, metal fibers, specific organic fillers) that mediate between the friction interface and environmental humidity. These intermediaries prevent excessive moisture absorption while maintaining friction properties, thus stabilizing the friction coefficient in humid conditions without copper
Solution Approach 2:
The patent optimizes composition parameters (filler ratios, binder types, particle size distributions) to control moisture interaction. By adjusting these parameters, the material achieves both low copper content and stable friction characteristics after humidity exposure
3Temperature
If graphite with median diameter of 1-30 μm is added, then thermal conductivity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a practical parameter range for graphite particle size (median diameter 1-30 μm) that balances thermal conductivity with manufacturability. This parameter optimization resolves the contradiction by avoiding excessively tight tolerances while ensuring adequate thermal 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 composition ensures a stable friction coefficient across various braking conditions and environmental changes, enhancing the performance of friction materials in both conventional and controlled braking systems.
Implementation Method 1
One representative function of copper is the impartation of thermal conductivity. Because copper has a high thermal conductivity, the heat generated during braking can be diffused from the friction interface
Implementation Method 2
Because copper exhibits superior ductility and malleability, it can expand across the friction material surface during braking to form a coating film
Implementation Method 3
Friction materials such as disc brake pads and brake linings perform a braking role by friction against a mating material such as a disc rotor or a brake drum
Data Source
AI summary
A friction material composition containing a binder, an organic filler, an inorganic filler and a fibrous base material, wherein the friction material composition either contains no copper as an element or has a content of copper as an element that does not exceed 0.5% by mass, contains α-alumina and γ-alumina in a mass ratio within a range from 1:20 to 1:5, contains a silicone-containing phenol resin, contains 20 to 35% by mass of a titanate salt, contains 3 to 7% by mass of a graphite having a median diameter of 1 to 30 μm, and contains antimony trisulfide.