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A Graphite Sheet, also known as flexible graphite sheet or expanded graphite sheet, is a versatile sealing and thermal management material manufactured from high-purity natural graphite. Through a chemical and thermal expansion process, the graphite flakes are exfoliated and then compressed into a flexible, foil-like material without the use of binders. Kaxite Sealing specializes in producing premium-grade graphite sheets that offer exceptional performance in demanding applications. This unique material retains the inherent beneficial properties of graphite—excellent thermal conductivity, chemical inertness, and natural lubricity—while gaining formability and resilience. It is an indispensable component in industries ranging from automotive and aerospace to chemical processing and energy generation, providing reliable sealing and heat dissipation where traditional materials fail.
Kaxite Sealing offers a comprehensive range of graphite sheet products tailored to specific application requirements. The following tables outline our standard material grades and their key technical parameters.
| Grade Code | Primary Description | Density Range (g/cm³) | Typical Applications |
|---|---|---|---|
| KX-GS100 | Standard Purity, Flexible | 1.0 - 1.1 | General purpose gaskets, furnace seals |
| KX-GS200 | High Density, Reinforced | 1.5 - 1.8 | High-pressure flange gaskets, heat exchangers |
| KX-GT300 | Thermally Conductive | 1.1 - 1.3 | Heat sinks, battery thermal management, LED cooling |
| KX-GC400 | Corrosion Resistant (Impregnated) | 1.2 - 1.5 | Chemical processing, aggressive acid service |
| KX-GF500 | Foil-Laminated | 1.0 - 1.2 (core) | Exhaust gaskets, EMI/RFI shielding composites |
| Property | Test Method | KX-GS100 | KX-GS200 | KX-GT300 | KX-GC400 | ||
|---|---|---|---|---|---|---|---|
| Density (g/cm³) | ASTM D792 | 1.05 | 1.65 | 1.2 | 1.35 | ||
| Tensile Strength (MPa) | ASTM D828 | 4.5 | 8.0 | 5.5 | 6.0 | ||
| Compressibility (%) | ASTM F36 | 40 | 25 | 35 | 30 | ||
| Recovery (%) | ASTM F36 | 15 | 10 | 18 | 12 | ||
| Thermal Conductivity (W/m·K) | ASTM E1461 | 120 | 90 | 150 | 110 | ||
| Maximum Service Temp in Air (°C) | - | 450 | 500 | 400 | 550* | ||
| Ash Content (%) | ASTM D5630 | < 1.0 | < 1.0 | < 0.5 | < 2.0** | ||
| pH Value | ASTM E70 | 6-8 | 6-8 | 6-8 | 5-7 | ||
| * Enhanced by impregnation. ** Includes impregnating agent. | |||||||
The versatility of graphite sheet makes it a critical material across numerous sectors. Its primary function is to create reliable static seals in flange connections for pipes, valves, and vessels handling steam, hot oils, aggressive chemicals, and gases. In the automotive industry, it is used for exhaust manifold gaskets, EGR systems, and fuel cell seals. Within electronics, high-thermal-conductivity grades like Kaxite Sealing's KX-GT300 are essential for managing heat in power transistors, CPUs, and battery packs. The aerospace industry utilizes it for sealing in engines and environmental control systems. Furthermore, it serves as a consumable in high-temperature furnaces and as packing material for pumps and valves, providing long service life with minimal maintenance.
Q: What is the main difference between a graphite sheet and a traditional rubber or fiber gasket?
A: Unlike organic materials, a graphite sheet is entirely inorganic and metallic-free, offering far superior temperature resistance and chemical inertness. It won't melt, burn, or become brittle. Its unique compressibility allows it to seal uneven surfaces more effectively than many harder gasket materials, and it maintains its seal under thermal cycling where rubber degrades and compressed fiber gaskets can relax and leak.
Q: Can a graphite sheet be used for sealing flammable or oxidizing media?
A: Pure graphite sheet can oxidize in air at high temperatures, which limits its use with strong oxidizing agents like nitric acid or certain gases. For applications involving oxidizers or to enhance oxidation resistance in high-temperature air service, Kaxite Sealing offers specially impregnated grades (like KX-GC400) or foil-laminated composites (KX-GF500) that provide a protective barrier, significantly extending service life and safety.
Q: How do I select the correct density for my application?
A: Density is a key selection criterion. Lower density sheets (e.g., 1.0-1.1 g/cm³) are more flexible and conformable, ideal for low to medium-pressure sealing on uneven surfaces. Higher density sheets (e.g., 1.5-1.8 g/cm³) offer greater mechanical strength, lower creep relaxation, and are better suited for high-pressure flange connections and applications requiring structural integrity. The engineers at Kaxite Sealing can help you determine the optimal grade based on your temperature, pressure (PSI/bar), flange condition, and media.
Q: Is graphite sheet electrically conductive?
A: Yes, graphite is an excellent conductor of electricity. This property is beneficial for applications requiring EMI/RFI shielding or electrical grounding across a gasketed joint. However, it means graphite sheet should not be used as an electrical insulator. For thermal management in electronics, this conductivity is often managed through proper design to prevent short circuits.
Q: How should graphite sheet gaskets be installed and torqued?
A: Proper installation is crucial. The flange surfaces should be clean, dry, and free of major scratches. The graphite sheet gasket is placed between the flanges. Bolting should follow a star-pattern sequence to ensure even compression. Torque values are typically lower than those for harder gaskets like spiral-wound; over-torquing can crush and split the graphite. It is essential to follow the recommended torque procedure provided by Kaxite Sealing or the equipment manufacturer, often involving multiple incremental tightening steps.
Q: Can graphite sheets be cut and fabricated into custom shapes?
A: Absolutely. One of the major advantages of graphite sheet is its easy machinability. It can be cleanly cut with sharp blades, die-cut, punched, or even CNC routed into complex gasket profiles, washers, and seals with precise inner and outer diameters. Kaxite Sealing offers comprehensive fabrication services, supplying ready-to-install custom gaskets to reduce on-site waste and installation time.
Q: How does the thermal conductivity of a graphite sheet compare to other materials?
A: Graphite sheet has exceptionally high in-plane thermal conductivity, often ranging from 80 to 150 W/m·K in standard grades, and even higher in specialized products. This is significantly better than traditional gasket materials (often less than 1 W/m·K) and rivals many metals. For comparison, aluminum is about 205 W/m·K. This makes it not just a seal, but an active component in heat spreading and dissipation systems.
Q: What are the storage and handling considerations for graphite sheet?
A: Store graphite sheets in a cool, dry place away from direct moisture. While the material itself is not hygroscopic, prolonged exposure to humidity can lead to slight surface oxidation or make handling messy. Sheets should be kept flat to avoid creasing. Wear gloves when handling large sheets to prevent oils from your skin from contaminating the material, which could affect performance in ultra-clean or high-vacuum applications.
