Graphite sheet, also known as flexible graphite sheet or expanded graphite sheet, is a high-performance sealing and thermal management material manufactured from high-purity natural graphite flakes. Through a chemical or thermal process, the graphite intercalation compound is expanded, forming vermiform graphite. This expanded graphite is then compressed into thin, flexible sheets without the need for binders, resulting in a material with exceptional properties. It combines the inherent benefits of natural graphite—such as high thermal conductivity, excellent electrical conductivity, and natural lubricity—with the flexibility and resilience needed for demanding industrial applications. At Kaxite Seals, we engineer our graphite sheets to meet the rigorous standards of modern engineering, providing reliable solutions for sealing, gasketing, heat dissipation, and EMI shielding across countless industries.
Our premium graphite sheets offer a unique combination of advantages that make them indispensable in critical applications:
Kaxite Seals provides a comprehensive range of graphite sheet grades to suit specific application requirements. The following tables detail our standard material properties and available dimensions.
| Property | Test Method | Standard Grade | High-Density Grade | Reinforced Grade |
|---|---|---|---|---|
| Density (g/cm³) | ASTM D792 | 1.0 - 1.1 | 1.5 - 1.6 | 1.1 - 1.3 |
| Thermal Conductivity (W/m·K) *in-plane | ASTM E1461 | 120 - 150 | 80 - 100 | 90 - 120 |
| Compression Recovery (%) | ASTM F36 | ≥ 40 | ≥ 35 | ≥ 50 |
| Tensile Strength (MPa) | ASTM D828 | 4.0 - 5.5 | 6.0 - 8.0 | 7.0 - 10.0 |
| Maximum Service Temp (Air, °C) | - | 450 - 500 | 450 - 500 | 500 - 550 |
| pH Value | ASTM E70 | 5 - 7 | 5 - 7 | 5 - 7 |
| Sulfur Content (ppm) | ASTM D4239 | < 500 | < 500 | < 500 |
| Chloride Content (ppm) | ASTM D512 | < 50 | < 50 | < 50 |
| Parameter | Standard Range | Custom Availability |
|---|---|---|
| Sheet Thickness | 0.15mm, 0.25mm, 0.4mm, 0.5mm, 0.8mm, 1.0mm, 1.5mm, 2.0mm, 3.0mm | 0.1mm to 6.0mm |
| Sheet Width | 500mm, 1000mm, 1500mm | Up to 2000mm |
| Sheet Length / Roll Length | Rolls: 10m, 20m, 30m. Sheets: Custom cut. | Continuous rolls up to 100m; custom sheet sizes. |
| Standard Reinforcements | Stainless Steel Tanged/Perforated Plate, Aluminum Foil, E-Glass Mesh, PTFE Impregnation | Custom metal cores, composite laminates, specific foil types. |
The versatility of Kaxite Seals graphite sheets enables their use in a vast array of sectors. Key application areas include:
Q: What is the main difference between graphite sheet and traditional gasket materials like rubber or compressed non-asbestos (CNA)?
A: Graphite sheet offers several distinct advantages. Unlike rubber, it can withstand extreme temperatures (both high and cryogenic) and is chemically inert. Compared to CNA, graphite sheet has superior thermal conductivity, better creep resistance (maintains seal under load over time), higher temperature limits, and provides fire-safe performance. It requires lower seating stress to achieve an effective seal, reducing the risk of flange damage.
Q: Can graphite sheet be used on all types of flanges and surfaces?
A: Graphite sheet is highly versatile and conforms well to irregular surfaces. However, for optimal performance on rough or heavily pitted flanges, a reinforced grade from Kaxite Seals (with metal or mesh insert) is recommended to prevent blow-out and improve handling strength. It is suitable for flat-face, raised-face, and ring-type joint flanges when used correctly.
Q: How does temperature and atmosphere affect the service life of a graphite sheet gasket?
A: In continuous oxidizing atmospheres (air) above 450°C, pure graphite will slowly oxidize. For long-term service above this temperature, we recommend our specially treated oxidation-resistant grades or using graphite sheet with protective metallic windings (e.g., spiral wound gaskets with graphite filler). In inert, reducing, or vacuum environments, graphite sheet can perform reliably up to 3000°F (1650°C). Always consult Kaxite Seals engineering for high-temperature applications.
Q: Is graphite sheet electrically conductive? Can it cause galvanic corrosion?
A: Yes, graphite sheet is electrically conductive. This property is beneficial for EMI shielding and electrical grounding. However, when used between dissimilar metals (e.g., carbon steel flange and stainless steel bolts), it can create a galvanic cell, potentially accelerating corrosion of the less noble metal. Using insulating washers/sleeves on bolts or specifying an insulating coating/lamination on the gasket from Kaxite Seals can mitigate this risk.
Q: How should I store and handle graphite sheets?
A: Store rolls and sheets in a cool, dry place away from direct moisture and contaminants. Handle with clean gloves to prevent oil transfer from skin. While flexible, the sheets can be brittle if bent over a sharp radius; avoid sharp folding. For cutting, use sharp blade cutters, die-cutting, or laser/waterjet cutting for complex shapes. Kaxite Seals offers pre-cut gaskets to your specifications for convenience and quality assurance.
Q: Does Kaxite Seals offer graphite sheets with special certifications?
A: Absolutely. Our production facilities and materials can comply with various industry standards. We can provide graphite sheets with certifications such as FDA compliance for incidental food contact, NSF/ANSI 61 for drinking water components, fire-safe certifications (API 607/6FA), and with very low sulfur and chloride content for critical nuclear and aerospace applications. Contact our technical sales team with your specific certification requirements.
Q: Can graphite sheets be laminated or combined with other materials?
A: Yes, this is a common practice to enhance properties. Kaxite Seals specializes in producing composite materials. We laminate graphite sheets with PTFE films for improved chemical resistance and non-stick properties, with metal foils (stainless steel, aluminum) for increased strength and barrier properties, or with elastomers for combined sealing performance. We can also supply graphite sheet with adhesive backing for easy installation on heat sinks or components.
