Phosphate-Coated Graphite Solid Lubricant for High-Temperature Brakes
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Solution Overview
Problem
Non-asbestos brake friction materials face inadequate lubricating characteristics at high temperatures, leading to wear and abnormal noise, and existing methods to enhance graphite's oxidation and thermal resistance do not effectively improve lubrication performance.
Innovation Solution
A solid lubricant is developed by coating graphite with a phosphate layer, specifically aluminum or magnesium phosphate, using a wet or dry pretreatment method followed by a phosphate aqueous solution, which enhances thermal and oxidation resistance while improving high-temperature lubrication performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphite is used as a solid lubricant, then lubricating performance is provided, but thermal resistance and oxidation resistance are insufficient at high temperatures
Solution Approach 1:
The invention creates a composite material by coating graphite particles with a phosphate layer (aluminum phosphate or magnesium phosphate). This composite structure combines the lubricating properties of graphite with the thermal and oxidation resistance of phosphate, resolving the contradiction between lubrication performance and high-temperature stability.
Solution Approach 2:
The invention changes the surface chemical composition parameter of graphite by introducing phosphate coating. This parameter change enhances the thermal resistance and oxidation resistance without compromising the fundamental lubricating mechanism of graphite, allowing the material to maintain reliability at elevated temperatures.
2Reliability
If a phosphate coating is applied to graphite, then thermal resistance and oxidation resistance are improved, but the complexity of the production process increases
Solution Approach 1:
The invention applies preliminary action by performing surface treatment (wet method or dry method) on graphite particles before phosphate coating. This pre-treatment activates the graphite surface, ensuring better adhesion of the phosphate layer and reducing the need for complex subsequent processing steps.
Solution Approach 2:
The invention uses an intermediary approach by employing a phosphate aqueous solution as the coating medium. This liquid intermediary allows for uniform and controlled deposition of phosphate on graphite particles, simplifying the coating process compared to direct solid-state reactions or complex vapor deposition methods.
3Reliability
If SiC covering layer is coated on carbon material, then oxidation resistance is improved, but cracks occur due to thermal expansion difference
Solution Approach 1:
The invention changes the material selection parameter by replacing SiC with phosphate (aluminum phosphate or magnesium phosphate) as the coating material. Phosphate has thermal expansion properties more compatible with graphite, preventing crack formation while maintaining oxidation resistance and structural stability at high temperatures.
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 phosphate-coated graphite solid lubricant significantly improves thermal resistance and oxidation resistance, providing enhanced lubrication performance at high temperatures, suitable for use in non-asbestos brake friction materials and sliding components.
Implementation Method 1
the solid lubricant is more significantly improved in thermal resistance and oxidation resistance than graphite
Implementation Method 2
enhanced in lubricating performance at high temperature
Data Source
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AI summary
A method for producing a solid lubricant includes steps of preparing and coating. A phosphate aqueous solution prepared by the step of preparing is an aqueous solution containing at least one of aluminum dihydrogen phosphate and magnesium dihydrogen phosphate in an amount of 0.5 to 10% by mass. A graphite material is coated with a phosphate using the phosphate aqueous solution. The graphite material is used at a ratio of 40 to 50 parts by mass based on 100 parts by mass of the aqueous solution.