Copper-Free Friction Material for Disc Brake Pads
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Solution Overview
Problem
Conventional non-asbestos-organic (NAO) friction materials for disc brake pads, which contain copper, face issues with wear resistance and stability under high temperatures and loads, and are subject to regulatory bans due to copper contamination concerns.
Innovation Solution
A friction material composition without copper, utilizing monoclinic zirconium oxide as an inorganic friction modifier, resilient graphitic carbon and calcined coke as carbon-type lubricants, and layered mineral particles to enhance wear resistance and stability, with specific weight percentages and particle sizes to maintain friction coefficient stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper component is added to NAO friction material to improve braking performance, then braking effectiveness is improved, but environmental pollution increases due to copper discharge
Solution Approach 1:
The invention removes the copper component from the friction material composition entirely, extracting the harmful element while maintaining braking performance through alternative inorganic friction modifiers such as zirconium oxide and titania
Solution Approach 2:
The invention changes the chemical composition parameters by replacing copper-based friction modifiers with copper-free alternatives, specifically using inorganic compounds like zirconium oxide (5-20 wt%) and titania (3-15 wt%) to achieve the same friction and wear properties without environmental pollution
2Strength
If zirconium oxide is added to improve wear resistance under high temperature, then wear resistance is improved, but excessive zirconium oxide causes volumetric shrinkage and reduces wear resistance
Solution Approach 1:
The invention optimizes the particle size parameter of zirconium oxide to 30μm or less, preventing excessive volumetric shrinkage during high-temperature service while maintaining effective wear resistance. This specific particle size parameter change ensures the zirconium oxide remains stable and embedded in the friction material matrix
Solution Approach 2:
The invention creates a composite friction material system combining multiple inorganic components including zirconium oxide (5-20 wt%), titania (3-15 wt%), and other fillers, where the synergistic interaction between components enhances wear resistance while maintaining volumetric stability under high-temperature conditions
3Object-generated harmful factors
If copper component is removed from friction material, then environmental pollution is reduced, but wear resistance and braking stability under high temperature may deteriorate
Solution Approach 1:
The invention changes the composition parameters by introducing specific inorganic friction modifiers (zirconium oxide 5-20 wt%, titania 3-15 wt%) with controlled particle sizes and ratios, achieving copper-free formulation that maintains braking stability and wear resistance through optimized material parameters
Solution Approach 2:
The invention develops a composite friction material containing multiple inorganic components including zirconium oxide, titania, and other fillers in specific ratios, creating a synergistic system that provides both environmental benefits and sustained braking performance under high-temperature conditions without copper
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 provides excellent wear resistance and stable braking effectiveness without copper, meeting regulatory requirements and maintaining friction coefficient stability under high temperature and load conditions.
Implementation Method 1
the inorganic friction modifier comprises 10 - 40 weight % of a monoclinic zirconium oxide with an average particle diameter, which is a 50% particle size (D50) measured by laser diffraction method, of 1 - 8μm
Implementation Method 2
when the friction material is subject to the history of high temperatures and high loads
Implementation Method 3
the lubricant comprises 1.5 weight % or more of a resilient graphitic carbon as a carbon type lubricant relative to the total amount of the friction material composition and a calcined coke also as a carbon type lubricant
Data Source
AI summary
[Object] The present invention provides a friction material used for a disc brake pad, which is manufactured by forming a non-asbestos-organic (NAO) friction material composition that does not contain a copper component, which provides an excellent wear resistance and a highly stable braking effectiveness even after being subjected to a history of high temperatures and high loads. [Means to Resolve] The friction material composition for the friction material molding containing, as an inorganic friction modifier, 10 - 40 weight % of a monoclinic zirconium oxide with an average particle diameter of 1 - 8µm relative to the total amount of the friction material composition, 1.5 weight % or more of a resilient graphitic carbon as a carbon type lubricant relative to the total amount of the friction material composition, and a calcined coke also as a carbon type lubricant, where total amount of the resilient graphitic carbon and the calcined coke is 2 - 8 weight % relative to the total amount of the friction material composition and a weight ratio of the resilient graphitic carbon and the calcined coke is 4:6 - 8:2. It is preferable that the friction material composition contains 2 - 6 weight % of the layered mineral particle as the inorganic friction modifier relative to the total amount of the friction material composition and that the layered mineral particle is mica.