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Graphite and Its Unique Characteristics

At first glance, pencils, car brakes, and dry cell batteries (e.g., AA, etc.) may not seem to have much in common; however, they all include a common ingredient: graphite. This mineral is found in metamorphic and igneous rock and is a naturally occurring form of crystalline carbon. It has many properties that make it suitable for use in a range of consumer, industrial, medical, food processing, and other applications.

Graphite is a very low-friction material with high compressive strength. For these reasons, it is commonly used to make gaskets, seals, lubricants, and valve packing material in mechanical, electrical, and other applications. Here, we will discuss some of the characteristics that make it an ideal choice for sealing and dry lubrication.

Built-In Lubrication and No Galling

The physical structure of graphite reacts with water vapor in the air to form a very thin, very tough layer when applied to parts. This slick film resists friction at high and low speeds and high temperatures, making it a durable and highly effective dry lubricant. It also resists seizing and galling.

Graphite is naturally porous and can be used as-is or impregnated with resins, copper, silver, molten ceramic, and other materials to improve strength, electrical conductivity, oxidation resistance, or other properties. Because it is porous, graphite can absorb water; however, some formulations can provide a water-repellent coating.

Corrosion Resistance

Graphite is chemically inert and resists corrosion. As a result, certain grades can be safely used for lubrication in food and pharmaceutical processing equipment. Broad chemical resistance also allows graphite components to be used reliably in systems requiring contact with corrosive materials, such as chemical, oil, and petrochemical processing activities. Care should be taken to avoid exposing graphite to oxygen at temperatures above about 850°F to limit oxidation. However, graphite gaskets have been used in non-oxidizing atmospheres to 3,000°F and higher.

High Compressive Strength

Graphite has high compressive strength, meaning it maintains its structure even when it is subjected to substantial crushing force. Typical ratings for graphite range from 31 MPa to 345 MPa (4.49617 ksi to 50.038 ksi). It also has a high modulus of elasticity, which means it can withstand high levels of stress and will show some return though not to its original thickness. Sealing applications typically include high, sustained compression forces; therefore, graphite gaskets and seals are an excellent choice.

Good Thermal Conductivity

In high-temperature applications, graphite remains stable and retains its shape as it will not creep or cold flow. It is a good thermal conductor and resists thermal shock. It also increases in strength as temperature increases, as long as oxidation is prevented. These qualities make it useful for gaskets, seals, and lubrication in high-temperature systems.

Why Choose MPRC Seals

At Master Packing and Rubber Company, we specialize in gaskets, seals, and valve packing made from graphite and graphite-based materials. We also supply PTFE joining sealant in adhesive-backed ribbons and tape and valve stem packing. Our capabilities include custom gasket and seal manufacturing, molding, and splicing. We are ISO 9001:2015-and AAR-M1003 certified and committed to providing innovative solutions for a range of industries.

Contact us today to learn more about our graphite gaskets, seals, and capabilities.