Brake Pad Geopolymer Binder Moisture Control to Prevent Cracking
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Solution Overview
Problem
Existing methods for producing non-asbestos friction materials for brake pads involve safety risks and produce scrap material due to uncontrolled moisture content in geopolymer binders, leading to cracking and flaking, and are difficult to recycle.
Innovation Solution
A method using a geopolymeric binder made from SiO2 and Al2O3 precursors, with controlled moisture content between 4% to 16%, is used to produce friction materials, eliminating organic binders and allowing easy recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If dry grinding of caustic soda is used to produce geopolymer binder, then chemical efficiency is improved, but operator safety deteriorates due to inhalation risks and uncontrolled moisture absorption
Solution Approach 1:
The patent extracts the harmful dry grinding process and replaces it with wet mixing using aqueous sodium silicate solution. This removes the source of fine volatile sodium hydroxide powders that cause inhalation risks, while maintaining the chemical efficiency of geopolymer binder production.
Solution Approach 2:
The patent introduces water as an intermediary medium in the form of aqueous sodium silicate solution. This mediator allows the chemical reaction to proceed efficiently without generating harmful dry powders, thus protecting operator safety while maintaining chemical efficiency.
2Ease of manufacture
If uncontrolled moisture content in geopolymer binder is used, then manufacturing simplicity is improved, but product quality deteriorates due to flaking and cracking
Solution Approach 1:
The patent implements feedback control by specifying that the geopolymer binder must have residual moisture content controlled within 4-16% before being used in friction material. This feedback mechanism ensures that the binder quality is monitored and adjusted to prevent flaking and cracking, while maintaining ease of manufacture through clear specification limits.
3Ease of operation
If high residual moisture content in geopolymer powder is used, then ease of handling is improved, but production efficiency deteriorates due to scrap material and recycling difficulties
Solution Approach 1:
The patent changes the moisture content parameter to an optimal range of 4-16%, which balances ease of handling with production efficiency. This parameter optimization prevents excessive moisture that would cause handling difficulties while avoiding low moisture content that would lead to scrap and recycling issues.
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 method produces brake pads with improved resistance to heat, optimal tribological characteristics, and ease of manufacturing, reducing scrap and ensuring consistent quality.
Implementation Method 1
a binder that is constituted for at least the 90% by a geopolymer
Implementation Method 2
dried through an atmospheric pressure drying process
Data Source
AI summary
Method for obtaining a friction material for a brake pad wherein a wet paste formed by mixing an alkaline silicate solution with metakaolin is spread on a support in a layer or tape and subsequently subjected to a thermal treatment to form a geopolymer aggregate; wherein the thermal treatment consists in drying the wet paste to a completely dried or almost completely dried geopolymer aggregate having a moisture content lower than a desired moisture content in the final geopolymer; and wherein the completely dried or almost completely dried geopolymer is ground to a powder, which is then re-wetted to a desired moisture content by addition of water or of a hydrated salt.