NAO Brake Friction Material for Humidity-Resistant Corrosion Control
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Solution Overview
Problem
Conventional non-asbestos-organic (NAO) friction materials used in disc brake pads can cause seizure due to corrosion when used in disc brakes with electronic parking brake functions, especially under high humidity conditions.
Innovation Solution
The friction material composition includes 2-6 weight % of alkali metal or alkaline earth metal salts as pH adjusters, 1-7 weight % of fibrillated organic fibers, and specific additives such as zinc sulfide, porous inorganic particles, and magnesium potassium titanate to maintain rust inhibition and prevent corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If NAO friction material is used to reduce brake noise, then quietness and stillness in braking operation is improved, but seizure due to corrosion occurs when used in disc brakes with electronic parking brake function under high humidity conditions
Solution Approach 1:
The patent introduces water-repelling materials (silicone rubber, fluoropolymer) as intermediary substances that form protective films between the friction material and the disc rotor. These intermediary layers prevent direct contact between moisture and the friction material components, thereby eliminating the corrosion pathway while maintaining the low-noise characteristics of NAO friction material.
Solution Approach 2:
The patent creates a hydrophobic, water-repelling environment on the friction material surface through the addition of silicone rubber and fluoropolymer. This inert-like protective layer isolates the friction material from the corrosive humid environment, preventing rust formation on the disc rotor even when the parking brake is engaged for extended periods.
2Reliability
If pH adjuster (alkali metal salt and/or alkaline earth metal salt) is added to inhibit rusting, then rust inhibition is improved, but the inhibition effect dramatically drops after prolonged exposure to high humidity state
Solution Approach 1:
The patent incorporates water-repelling materials (silicone rubber, fluoropolymer) into the friction material composition before use. These materials preliminarily establish a protective hydrophobic barrier that prevents moisture penetration, thereby preserving the effectiveness of pH adjusters (alkali metal salts and alkaline earth metal salts) over extended periods in humid conditions.
Solution Approach 2:
The patent creates a composite friction material system combining traditional NAO components (cellulosic fiber, organic binder, friction modifiers) with water-repelling additives (silicone rubber, fluoropolymer). This composite structure integrates the rust-inhibiting function of pH adjusters with the moisture-barrier function of water-repelling materials, achieving synergistic long-term corrosion protection.
3Reliability
If water-repelling material is added to form water-repelling film, then initial rust inhibition is improved, but the inhibition effect is limited to initial stage and sticking occurs after prolonged high humidity exposure
Solution Approach 1:
The patent merges two protective mechanisms into a unified friction material system: (1) water-repelling materials (silicone rubber, fluoropolymer) that form hydrophobic films to prevent moisture contact, and (2) pH adjusters (alkali metal salts, alkaline earth metal salts) that provide chemical rust inhibition. This combination ensures both immediate and long-term protection against corrosion.
Solution Approach 2:
The patent modifies the chemical composition parameters of the friction material by incorporating specific amounts of water-repelling materials (0.1-5 weight% silicone rubber, 0.1-5 weight% fluoropolymer) and pH adjusters (2-20 weight% alkali metal salt, 2-20 weight% alkaline earth metal salt). These parameter changes transform the friction material from a moisture-permeable structure to a moisture-resistant composite with sustained corrosion protection.
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 friction material effectively prevents seizure due to corrosion and maintains rust inhibition even after prolonged exposure to high humidity, ensuring reliable brake performance.
Implementation Method 1
the friction material composition contains 2 - 20 weight % of an alkali metal salt and/or an alkaline earth metal salt as a pH adjuster relative to the total amount of the friction material composition
Implementation Method 2
the friction material composition contains 0 - 5 weight % of a water-repelling component relative to the total amount of the friction material composition
Data Source
AI summary
[Object] To provide a friction material, which is manufactured by forming a non-asbestos-organic (NAO) friction material composition, used for a disc brake assembled in such as a passenger car, which does not degrade the inhibitory effect of rusting and prevents seizure due to corrosion even if the automotive while the parking brake in operation is left under a high humidity state for a long period of time. [Means to Resolve] A friction material, which is manufactured by forming the NAO friction material composition including a binder, a fiber base material, a friction modifier, a lubricant, a pH adjuster, and a filler, where the friction material composition contains 2 - 6 weight % of alkali metal salt and/or alkaline earth metal salt as the pH adjuster relative to the total amount of the friction material composition, 1 - 7 weight % of fibrillated organic fiber as the fiber base material relative to the total amount of the friction material composition, and 0 - 0.5 weight % of water-repelling component relative to the total amount of the friction material composition.