Friction Material Using Artificial Graphite and Zinc Powder
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Solution Overview
Problem
Conventional friction materials experience reduced friction coefficient and sticking issues under high-temperature high-load conditions, leading to eccentric wear and impaired brake function, particularly at temperatures above 400°C, where the strength of the material is insufficient.
Innovation Solution
A friction material comprising a fibrous material, a binder, artificial graphite with an average particle diameter of 1,000 to 3,000 µm, an inorganic filler with a plurality of convex parts such as barium sulfate, calcium carbonate, or potassium titanate, and zinc powder, which enhances strength and prevents sticking by improving the interface state and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a plate-like or flake-like filler is used to replace whisker filler, then environmental hygiene is improved, but the friction material strength and wear resistance under high-temperature high-load conditions deteriorate
Solution Approach 1:
The patent uses a composite filler system combining plate-like filler (such as mica or glass flake) with spherical filler (such as alumina or silica beads). This composite approach allows the plate-like filler to provide environmental benefits while the spherical filler compensates for strength deficiencies, achieving both ecological compliance and mechanical performance under high-temperature conditions up to 400°C
Solution Approach 2:
The patent optimizes the particle size parameters of the plate-like filler, specifying a thickness of 2-10 μm and diameter of 5-50 μm. By controlling these dimensional parameters, the filler maintains sufficient strength and wear resistance while preserving environmental hygiene benefits, resolving the contradiction between eco-friendliness and mechanical performance
2Strength
If conventional fillers are used to maintain friction material strength, then high-temperature strength is improved, but the friction coefficient reduction during fade under high-temperature high-load conditions worsens
Solution Approach 1:
The patent employs a composite filler system combining plate-like filler with spherical filler particles. This combination maintains friction material strength at high temperatures while the specific morphology and distribution of the composite filler prevent excessive friction coefficient reduction during fade, ensuring both structural integrity and reliable braking performance
Solution Approach 2:
The patent creates local quality variations in the friction material structure by distributing different filler types in specific regions. The plate-like filler provides structural framework while spherical filler fills interstices, creating a hierarchical structure that simultaneously maintains strength and stabilizes friction coefficient under high-temperature high-load conditions
3Power
If the friction material is placed in pressurized state immediately after heat history, then brake function is maintained, but sticking to disc rotor occurs causing eccentric wear and vibration
Solution Approach 1:
The patent introduces zinc powder (0.1-5 wt%) as an intermediary substance that modifies the interface between friction material and disc rotor. The zinc acts as a lubricating agent that prevents direct metal-to-metal contact and sticking, allowing the friction material to withstand pressurized states after heat history without generating eccentric wear or vibration
Solution Approach 2:
The patent uses zinc powder, a relatively inexpensive material, that sacrificially protects the friction material-stick interface. The zinc oxidizes and forms a protective layer that prevents sticking, accepting its own degradation to prevent more serious damage to the braking system components
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 suppresses friction coefficient reduction and sticking, while enhancing the friction material's strength and reducing wear at high temperatures, ensuring reliable brake performance.
Implementation Method 1
an artificial graphite having an average particle diameter of 1,000 to 3,000 µm... contributes to improving the interface state between the rotor and the friction material during occurrence of fade under high-temperature high-load conditions
Implementation Method 2
zinc powder... enhances strength and prevents sticking by improving the interface state and mechanical properties
Implementation Method 3
an inorganic filler having a plurality of convex parts... effectively suppresses friction coefficient reduction... while enhancing the friction material's strength
Data Source
Figure 1
AI summary
An object of the present invention is to provide a friction material ensuring that reduction of the friction coefficient during occurrence of fade under high-temperature high-load conditions as well as sticking to a disc rotor immediately after heat history are suppressed and the friction material strength in a high temperature region is enhanced. The present invention relates to a friction material comprising a fibrous material, a binder and a friction modifier, wherein an artificial graphite having an average particle diameter of 1,000 to 3,000 µm and an inorganic filler having a plurality of convex parts are contained as the friction modifier.