The carbon graphite components used in vacuum furnaces are key thermal field components specifically designed for high-temperature environments in vacuum or inert atmospheres. They are widely applied in high-end manufacturing fields such as semiconductors, photovoltaics, hard alloys, advanced ceramics, aerospace materials, etc. These components are made of high-purity isostatic graphite, carbon-graphite composites, and graphite felts, through precise molding, high-temperature graphitization, and CNC processing. They possess core advantages such as high temperature resistance, low impurities, high electrical and thermal conductivity, and strong chemical stability. They are the fundamental guarantee for vacuum furnaces to achieve ultra-high temperature treatment and maintain a clean process environment.
| Property | Unit | High-Purity Isostatic Graphite | Carbon-Graphite Composite | Flexible Graphite Felt |
|---|---|---|---|---|
| Carbon Content | % | ≥99.99 | 95-98 | 99-99.5 |
| Ash Content | ppm | ≤5 | 50-200 | 10-50 |
| Density | g/cm³ | 1.85-1.95 | 1.65-1.80 | 0.10-0.25 |
| Electrical Resistivity | μΩ·m | 10-15 | 15-30 | 500-2000 |
| Thermal Conductivity (25°C) | W/(m·K) | 150-200 | 80-120 | 0.15-0.30 |
| Thermal Expansion Coefficient (25-1000°C) | 10⁻⁶/°C | 4.5-5.5 | 5.0-6.5 | 8.0-12.0 |
| Max Operating Temperature (Vacuum) | °C | 2800-3000 | 2200-2500 | 2500-2800 |
| Flexural Strength (Room Temp) | MPa | 45-60 | 30-45 | 0.5-2.0 |
| Compressive Strength (Room Temp) | MPa | 120-180 | 90-120 | 5-15 |
| Machining Tolerance | mm | ±0.01-±0.05 | ±0.05-±0.10 | ±1.0-±2.0 |
Manufacturing Process
Raw material preparation: Select high-quality calcined petroleum coke / asphalt coke (ash content < 50 ppm) to ensure high-purity raw materials
Forming process:
Isostatic pressing: Pressure ≥ 200 MPa, holding pressure ≥ 30 minutes, obtaining high-density isotropic green bodies
Mold pressing / hot pressing: Suitable for composite materials and structural components, improving production efficiency
Needle punching: Used for graphite felt type insulation materials
Multi-stage calcination: Gradually increase temperature to 1200-1500°C, hold for 72 hours+, carbonizing the binder to enhance strength
High-temperature graphitization: 2500-3200°C, holding for 24-50 hours, increasing graphitization degree, reducing resistivity, carbon purity can reach 99.99%+
Precision processing: CNC processing, tolerance controlled within ±0.01-±0.05 mm, meeting the requirements for precise assembly in vacuum furnaces
Surface treatment: Optional coating (SiC, PyC) or impregnation treatment, improving oxidation resistance and wear resistance
Technical Advantages and Performance Assurance
Temperature Adaptability: Can operate stably at temperatures ranging from 2000 to 3000°C in vacuum/inert atmosphere, far exceeding the limit of metal materials.
Purity Control: Key components use 99.99%+ high-purity graphite, with low gas emission rate, preventing contamination of the workpiece.
Structural Stability: Strength increases at high temperatures, with a low thermal expansion coefficient (4-6×10⁻⁶/°C), making it less prone to deformation.
Customization Capability: Can be customized to complex shapes according to DXF/STEP drawings, suitable for various types of vacuum furnaces.
Key Features
Excellent High-Temperature Resistance: Melting point 3850 ± 50°C, boiling point 4250°C, can operate stably at 2800°C in vacuum environment, and up to 3000°C for short periods
Outstanding Electrical & Thermal Conductivity: Resistivity 10-15 μΩ・m, thermal conductivity 120-200 W/(m・K), ensuring rapid heating and uniform temperature field
High Purity & Low Impurity: Carbon content ≥ 99.99%, ash content < 5 ppm, low gas emission rate, suitable for semiconductor, photovoltaic and other processes with high cleanliness requirements
Application Fields & Value Analysis
Semiconductor and Photovoltaic Industry: Used in single-crystal silicon/multi-crystal silicon growth furnaces and PECVD equipment, providing a high-purity thermal environment to enhance crystal quality and conversion efficiency
Hard Alloy and Superhard Materials: As heating elements and support components in vacuum sintering furnaces, ensuring material densification and performance consistency, extending tool lifespan by 30%
Advanced Ceramic Manufacturing: Sintering of materials such as silicon carbide and zirconia, improving ceramic strength and toughness, and reducing production costs
Aerospace Materials: Heat treatment of high-temperature alloys and titanium alloys, meeting lightweight and high-strength requirements, enhancing component reliability
New Energy Materials: Sintering of lithium battery positive electrode materials, ensuring material crystallinity and electrochemical performance stability
Quality Control & Certifications
Raw material testing: Carbon content, ash content, particle size distribution, impurity element analysis (ICP-MS)
Process control: Density uniformity testing, size accuracy control, porosity testing
Finished product inspection: Resistivity testing, thermal conductivity measurement, high-temperature stability testing, air tightness testing
International certifications: ISO 9001 Quality Management System, RoHS Environmental Certification, Semiconductor industry SEMI Standards Certification
Common Problem
Selection Guide
According to temperature requirements: ordinary graphite can be selected below 2000°C, high-purity isostatic graphite can be chosen between 2000°C and 2600°C, and ultra-high-purity graphite can be selected above 2600°C.
According to purity requirements: for semiconductor / photovoltaic industries, 99.99% or higher purity graphite is selected, while for general industrial applications, 99.9% graphite can be chosen.
According to structural requirements: molded forming is selected for complex shapes, isostatic forming is chosen for high precision requirements, and graphite felt materials are selected for heat insulation needs.
According to service life: high-density graphite is selected for high-frequency usage scenarios, and surface coating can extend the service life by 2-3 times.
Packaging & Transportation
The products are packed with shockproof foam and hard cardboard boxes to prevent damage during transportation.
Precision components are individually packaged, with protective films and desiccants attached.
Anti-rust, anti-humidity, and anti-collision labels are provided, supporting various transportation methods such as sea, air, and land.
A detailed technical parameter table, quality inspection report, and installation guide are included.
| Parameter | Unit | Tubular Heater | Plate Heater | U-Shape Heater |
|---|---|---|---|---|
| Diameter/Thickness | mm | 10-100 | 5-50 | 8-80 |
| Length | mm | 100-3000 | 100-2000 | 200-2500 |
| Power Density | W/cm² | 10-30 | 8-25 | 10-30 |
| Max Surface Temperature | °C | 2200-2600 | 2000-2400 | 2200-2600 |
| Temperature Uniformity | °C | ±5-±15 | ±3-±10 | ±5-±15 |
| Connection Type | - | Threaded/Clamped | Bolted/Clamped | Bolted/Clamped |
| Material Grade | - | TOYO TTK-8, SGL R6710 | TOYO ISO-63, SGL R5710 | TOYO TTK-5, SGL R6710 |
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