Low-Density Thermally Conductive Graphite Material Production
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Solution Overview
Problem
Existing methods for producing low-density, high-strength thermally expanded graphite materials face challenges such as corrosive acid residues, inadequate adhesion, and loss of anisotropic thermal conductivity, making it difficult to create strong, corrosion-free, and uniformly conductive building elements without the need for binders.
Innovation Solution
A method involving the production of hydrolyzed graphite nitrate particles through chemical or electrochemical interaction with nitric acid, followed by thermal expansion in a specific fuel combustion atmosphere with controlled air-fuel equivalence ratio and specific heat, resulting in low-density thermally conductive material with neutral or basic pH and enhanced adhesion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional processes using sulfuric acid or nitric acid are used to produce TEG, then thermal expansion and structural properties are achieved, but corrosive acid residues remain in the material
Solution Approach 1:
The patent converts the harmful corrosive acid residues into beneficial neutral or basic pH properties by using alkaline substances (such as metal hydroxides, oxides, or carbonates) to neutralize the acidic components during the TEG production process. This transforms the harmful acidic environment into a neutral or basic final product that is non-corrosive to metal parts.
2Ease of manufacture
If low-density TEG plates are used to improve adhesion and form monoblocks, then surface area and adhesion are improved, but the plates disintegrate easily due to insufficient strength
Solution Approach 1:
The patent changes the physical and chemical parameters of TEG particles through controlled thermal expansion at specific temperatures (400-1600°C) and subsequent compaction at controlled pressures (0.1-10 MPa). These parameter changes create a dense, interlocked particle structure that simultaneously improves adhesion between plates and structural strength within plates, preventing disintegration while maintaining low overall density.
3Reliability
If high-density TEG is used to maintain anisotropic thermal conductivity, then thermal conductivity anisotropy is preserved, but the material becomes difficult to form into monoblocks without binders
Solution Approach 1:
The patent optimizes the density parameter within a specific range (0.03-0.1 g/cm³) that balances thermal conductivity anisotropy with manufacturability. By controlling the compaction pressure and temperature during production, the patent achieves sufficient particle interlocking for binderless monoblock formation while preserving the aligned structure necessary for anisotropic thermal conductivity parallel to the plate surface.
4Strength
If TEG particles are compacted to improve strength and adhesion, then mechanical strength increases, but thermal conductivity anisotropy is reduced
Solution Approach 1:
The patent precisely controls the compaction pressure parameter (0.1-10 MPa) to achieve optimal particle packing that enhances mechanical strength while preserving the preferential orientation of TEG particles. This controlled compaction maintains the layered structure necessary for thermal conductivity anisotropy parallel to the plate surface, unlike excessive compaction that would randomize particle orientation.
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 a low-density, high-strength thermally conductive material with improved adhesion and thermal conductivity, capable of forming monolithic sheets and structures without binders, ensuring effective heat distribution and structural integrity while avoiding corrosive residues.
Implementation Method 1
chemical or electrochemical interaction of natural graphite with nitric acid
Implementation Method 2
subsequent hydrolysis by washing with water
Implementation Method 3
obtaining particles of thermally expanded graphite by heating particles of hydrolyzed graphite nitrate
Implementation Method 4
heating particles of hydrolyzed graphite nitrate washed with water with a specific heat equal to or exceeding 4.7 KJ/g but not exceeding 12 KJ/g in an atmosphere of liquid or gaseous fuel combustion products
Implementation Method 5
subsequently compacting said thermally expanded graphite to an apparent density of from 0.03 to 0.1 g/cm3
Data Source
AI summary
This invention relates to the field of producing low-density, heat-conducting materials based on thermally-expanded graphite, which can be used for conducting heat and also for distributing heat, inter alia, in a range of high temperatures. The present method for producing a low-density, heat-conducting material from thermally-expanded graphite is characterized in that it includes the following stages: (A) producing particles of thermally-expanded graphite by heating particles of hydrolyzed graphite nitrate at a specific heating energy equal to or greater than 4.7 kJ/g in an atmosphere of products of the combustion of liquid or gas fuel in air with an air-fuel equivalence ratio of λ=0.8-1.1; and (B) subsequently compacting the above-mentioned thermally-expanded graphite to a density of from 0.03 to 0.1 g/cm3. The invention makes it possible to produce a low-density, heat-conducting material with high flexural strength and a high modulus of elasticity, which is characterized by the absence of acidic corrosive additives.