Sintered Friction Material Composition for High-Temperature Stability
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Solution Overview
Problem
Friction materials with copper as the main component face issues of reduced friction coefficient due to plastic flow at high temperatures, leading to environmental pollution and poor adhesion with sintered members, while low-temperature sintering compromises sinterability and adhesion.
Innovation Solution
A friction material composition with a matrix containing Fe, P, Ni, and Si, along with hard particles and lubricants, optimized to maintain a high friction coefficient and adhesion even at high temperatures, using specific mass percentage ratios to balance density, mechanical strength, and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If copper is used as the main component of the friction material, then the friction coefficient is high, but the material undergoes plastic flow at high temperatures leading to reduced friction coefficient
Solution Approach 1:
The patent changes the chemical composition parameters of the matrix material, specifically limiting copper content to 15 mass% or less and incorporating Fe, P, and Ni in controlled amounts. This compositional parameter change reduces the ductility and plastic flow tendency at high temperatures while maintaining adequate friction coefficient through the synergistic effect of the multi-element matrix and added hard particles.
Solution Approach 2:
The patent creates a composite friction material consisting of a multi-element matrix (Fe-P-Ni-Cu-Si) combined with hard particles (oxides, carbides, nitrides) and lubricants. This composite structure combines the benefits of different materials: the matrix provides binding and friction characteristics, hard particles provide wear resistance and friction stability, and lubricants control friction levels, together achieving high friction coefficient with dimensional stability at elevated temperatures.
2Stability of the object's composition
If low-temperature sintering is used to suppress plastic flow, then dimensional stability is improved, but sinterability is reduced leading to poor adhesion with metal back plate
Solution Approach 1:
The patent modifies the chemical composition parameters to include specific elements (P, Ni, Si) in controlled amounts that enhance both sinterability and dimensional stability. Phosphorus content of 0.05-5.0 mass% improves sinterability by promoting metallurgical bonding during sintering, nickel content of 40-75 mass% enhances high-temperature strength and adhesion, and silicon content of 0.5-3.0 mass% contributes to dimensional stability. This compositional optimization allows achieving adequate adhesion strength without requiring high-temperature sintering that would cause plastic flow.
3Force
If copper content is increased to maintain high friction coefficient, then friction performance is improved, but environmental pollution increases due to copper wear particles
Solution Approach 1:
The patent extracts and removes copper from the main component position in the friction material, limiting it to 15 mass% or less. This extraction eliminates the primary source of environmentally harmful copper wear particles while maintaining friction performance through alternative mechanisms provided by the Fe-P-Ni matrix combined with hard particles and lubricants.
Solution Approach 2:
The patent changes the compositional parameters by reducing copper content and introducing alternative elements (Fe, P, Ni, Si) that provide friction characteristics without the environmental drawbacks of copper. This parameter change substitutes problematic copper-based friction mechanisms with alternative material systems that are environmentally friendly while maintaining or improving friction coefficient.
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 achieves excellent adhesion and a high friction coefficient at elevated temperatures, reducing environmental impact and wear, while maintaining mechanical strength and preventing plastic flow.
Implementation Method 1
it is known that a friction material is produced through a low-temperature sintering step so as to suppress the occurrence of plastic flow
Implementation Method 2
excellent adhesion with a member intended to be joined, via sintering, to a friction member
Implementation Method 3
frictional heat is generated so that high temperature occurs
Implementation Method 4
this is prone to cause plastic flow of the friction material
Data Source
AI summary
A friction material according to the present invention comprises: 40 mass% or more to 80 mass% or less of a matrix of at least one kind selected from the group consisting of a metal, an alloy, a metal compound and an intermetallic compound; 5 mass% or more to 30 mass% or less of solid particles of at least one kind selected from the group consisting of a carbide, a nitride, an oxide and a sulfide of an element of at least one kind selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Mg and Si; and 5 mass% or more to 40 mass% or less of a lubricant of at least one kind selected from the group consisting of graphite, molybdenum disulfide, tungsten disulfide, boron nitride and calcium fluoride, wherein: the matrix comprises, as elements, at least, 20 mass% or more to 50 mass% or less of Fe, 0.05 mass% or more to 5.0 mass% or less of P, and 40 mass% or more to 75 mass% or less of Ni, based on a total amount of the matrix; and a content of Cu as an element is 15 mass% or less based on a total amount of the matrix.