Graphite-Aluminum Composite Material With High Conductivity and Low Expansion
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Solution Overview
Problem
Conventional composites of carbon/graphite-based materials and aluminum metal lack sufficient strength, thermal conductivity, and have high thermal expansion, making them unsuitable for structural and heat dissipation applications, particularly in environments with significant temperature fluctuations.
Innovation Solution
A composite is formed using a mixed powder of crystalline graphite and metal/ceramic powders with a silica-based inorganic binder, impregnated with molten aluminum, achieving a flexural strength of 90 MPa or higher, thermal conductivity of 240 W/m·K or higher, and a coefficient of thermal expansion of 6.0 ppm/K or lower.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If graphite materials are used as heat dissipation members, then thermal conductivity is improved, but strength is insufficient causing breakage or cracks
Solution Approach 1:
The invention creates a composite material by impregnating graphite porous bodies with molten aluminum or aluminum alloys. The resulting aluminum-graphite composite combines the high thermal conductivity of graphite with the strength and ductility of aluminum, resolving the contradiction between thermal conductivity and strength. The aluminum matrix provides structural integrity while graphite particles maintain thermal performance.
Solution Approach 2:
The invention changes the physical state of aluminum from solid to liquid (molten) during the impregnation process, allowing it to penetrate the graphite porous structure. After impregnation, the aluminum solidifies, creating a bonded composite. This parameter change enables effective combination of materials with different properties.
2Temperature
If copper is used as heat dissipation plate, then thermal conductivity is improved, but coefficient of thermal expansion difference causes cracks
Solution Approach 1:
The invention changes the material composition from pure copper to an aluminum-based composite containing graphite. This parameter change adjusts the coefficient of thermal expansion to be closer to that of silicon semiconductors, reducing thermal stress and preventing cracks while maintaining adequate thermal conductivity through the graphite content.
Solution Approach 2:
By creating an aluminum-graphite composite, the invention achieves a balanced combination of properties: aluminum provides low thermal expansion and strength, while graphite contributes thermal conductivity. This composite approach resolves the contradiction between thermal performance and thermal expansion compatibility.
3Weight of moving object
If conventional graphite materials are used, then weight is reduced, but thermal conductivity is insufficient compared to copper or aluminum
Solution Approach 1:
The aluminum-graphite composite maintains the lightweight advantage of graphite and aluminum while achieving superior thermal conductivity through the synergistic combination. The aluminum matrix provides continuous thermal pathways and the graphite particles enhance heat dissipation, together outperforming conventional graphite while remaining lightweight.
4Reliability
If SiC semiconductors are used, then electrical performance is improved, but operating temperature increases to around 200°C requiring better thermal management
Solution Approach 1:
The aluminum-graphite composite is specifically designed to handle the high operating temperatures of SiC semiconductors. The graphite component provides excellent thermal conductivity for heat dissipation, while the aluminum matrix offers thermal expansion compatibility with SiC, enabling reliable thermal management at elevated 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 composite exhibits high strength, thermal conductivity, and low thermal expansion, enabling its use in structural and heat dissipation applications without complex production steps, thus overcoming the limitations of existing materials.
Implementation Method 1
a silica-based inorganic binder is further added to the mixed powder
Implementation Method 2
impregnated with molten aluminum
Implementation Method 3
forming a composite from a molded body having voids and molten aluminum metal
Implementation Method 4
graphite powder composed of a natural graphite powder or a synthetic graphite powder each having a crystal structure that is not amorphous
Implementation Method 5
coefficient of thermal expansion of 6.0 ppm/K or lower
Data Source
AI summary
The present invention intends to realize a metal and/or ceramic/graphite-containing aluminum composite that is obtained by forming a composite using a carbon/graphite-based material and an aluminum material, that has a high strength, a high thermal conductivity, and a low coefficient of thermal expansion, and that can be industrially utilized in a wide range. The present invention also intends to develop a technique of providing the material. There is provided a metal and/or ceramic/graphite-containing aluminum composite obtained by forming a composite from a molded body and a molten aluminum metal or a molten aluminum alloy, wherein the molded body is formed of a material obtained by externally adding a silica-based binder to a mixed powder containing a powder of graphite which is not amorphous and a metal powder and/or ceramic powder, the metal and/or ceramic/graphite-containing aluminum composite has a flexural strength of 90 MPa or higher, a thermal conductivity of 240 W/m·K or higher in either the XY direction or the Z direction, and a coefficient of thermal expansion of 6.0 ppm/K or lower in either the XY direction or the Z direction. There is also provided a method for producing the composite.