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Intrinsic Thermal Conductivity
Graphite exhibits exceptional heat transfer capabilities among carbon allotropes, with in-plane thermal conductivity reaching 1500-2000 W/(m·K)—significantly surpassing copper (~400 W/(m·K)). This originates from:
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Delocalized π-electron system via sp² hybridization
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Rigid lattice structure with strong covalent bonds
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Phonon-dominated heat transfer mechanism (~4300 W/(m·K) at room temperature)
Key Thermophysical Parameters
| Property | Value Range | Physical Significance |
|---|---|---|
| CTE | 1.0×10⁻⁶ K⁻¹ | Superior dimensional stability at high temperatures |
| Thermal Shock Resistance | ΔT>1000℃ | Synergy of low elastic modulus (≈10 GPa) and high strength |
| Specific Heat Capacity | 706.9 J·kg⁻¹·K⁻¹ | Energy storage per unit mass |
| Sublimation Point | 3650℃ (1 atm) | Direct solid-gas phase transition |
| Operating Range | -200~3300℃ | Structural integrity in inert environments |
Temperature Response Mechanisms
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Enhanced Electron Mobility (100-2500℃)
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Carrier concentration increases to 10¹⁹ cm⁻³
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Electrical conductivity boost promotes heat transfer
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Lattice Vibration Evolution
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Low-T region (<-50℃): Phonon scattering dominance
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High-T region (>2000℃): Restricted Umklapp processes
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Oxidation Threshold (>427℃)
Oxidation rate in air:
Industrial Application Matrix
| Sector | Core Function | Critical Parameters |
|---|---|---|
| Electronics Cooling | Thermal interface material | κ∥>1500 W/(m·K) |
| Arc Steelmaking | Electrodes | Withstands 3000℃ plasma |
| Aerospace TPS | Thermal protection | CTE≈0.8×10⁻⁶/K (axial) |
| Crystal Growth | Crucibles | Purity>99.999% |
| Cryogenic Engineering | Seals | Maintains ductility at -269℃ |
Advanced Thermal Management Technologies
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Highly Oriented Pyrolytic Graphite (HOPG)
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Thermal anisotropy ratio: κ∥/κ⊥≈200
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Applied in concentrated PV cooling
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Graphene-Reinforced Composites
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5wt% addition increases κ by 300%
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Thermal diffusivity: 120 mm²/s
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Nuclear Reactor Moderators
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Neutron absorption cross-section: 3.5 mbarn
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High-T stability (>2500℃ continuous operation)
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Performance Boundaries
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Oxidation Prevention: Vacuum <10⁻³ Pa or argon atmosphere
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Low-T Brittleness Threshold: Isotropic graphite at -170℃
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Radiative Heat Limit: 7.3 MW/m² blackbody radiation at 3000℃
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Thermal Cycling Life: >5000 cycles at ΔT=1500℃ (aviation brake standard)
Experimental data: Single-crystal graphite reaches peak κ of 4000 W/(m·K) along (002) plane at 80K, attributed to extended phonon mean free path at cryogenic temperatures.
Material Selection Criteria
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High-T Applications (>2000℃)
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Prefer isostatically pressed graphite (density>1.85 g/cm³)
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Open porosity <15%
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Heat Exchange Systems
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Thermal anisotropy ratio >100
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Ash content <200 ppm
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Extreme Environment Seals
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Fluoropolymer impregnation for densification
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Thermal shock resistance factor >500 W/m
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This thermal analysis provides theoretical foundations for material selection in high-temperature systems, particularly critical for nuclear components, hypersonic vehicle TPS, and third-generation semiconductor cooling.
