Graphite powder for sealing materials

Micronized graphite is widely used in the sealing field, mainly utilizing its properties such as high temperature resistance, self-lubrication, chemical stability and compressibility. As a key material, Graphite powder for sealing materials is often applied to dynamic or static sealing in high-temperature, high-pressure or corrosive environments.

Core advantages for sealing

(1) High temperature resistance: It can work at -200℃~3000℃ (in non-oxidizing atmosphere), which is far superior to rubber or plastic sealing materials.

(2) Self-lubrication: The layered structure reduces the friction coefficient (0.1~0.3) and lessens the wear of sealing parts.

(3) Chemical inertness: Resistant to acids, alkalis and organic solvents (except strong oxidizing media such as concentrated nitric acid).

(4) Plasticity: Micronized powder is easy to fill irregular surfaces and form a dense sealing layer.

(5) Electrical/thermal conductivity: Suitable for sealing scenarios requiring heat dissipation or anti-static.

Common sealing forms and application scenarios

(1) Graphite powder for sealing packing Composition: Micronized graphite mixed with metal wires and fibers (such as carbon fibers) and pressed. Application: Dynamic sealing of valves, pump shafts and agitators (e.g., chemical pumps, high-temperature reaction kettles). Features: Pressure resistance up to 20MPa, needs to be used with grease to reduce starting torque.

(2) Flexible graphite seals (expanded graphite) Process: Micronized graphite is acidified, expanded and then pressed into gaskets, plates or spiral wound gaskets. Application: Static sealing of pipe flanges, heat exchangers and engine cylinder heads. Features: High rebound rate (≥40%), which can compensate for the unevenness of flange surfaces.

(3) Composite sealing materials Graphite + metal: Such as graphite-copper composite materials, used for high-speed bearing sealing. Graphite + polymer: Such as PTFE-graphite composite materials, which have both corrosion resistance and low friction.

(4) Dry sealing coating Process: Disperse micronized graphite in a binder and spray or brush it on the sealing surface.

Application: Anti-seize of high-temperature bolts and threaded joints.

Supplementary Notes

Particle size adjustable to meet dispersion needs in coatings, composites, etc.

• High carbon, low ash ensures purity for electronics, new energy, reducing impurities.

• Moderate specific surface area and tap density balance dispersibility and formability, suitable for slurry preparation, compression molding, etc.

• Low resistivity enables excellent conductivity, ideal for conductive additives and electrodes. Sealing Performance Test Standards and Parameters.

Parameter	Typical Value/Requirement	Test Standard
Particle Size	1–50 μm (The finer, the better the sealing performance)	ISO 13320
Density	1.0–1.8 g/cm³	ASTM D3800
Compressibility	15–30%	GB/T 5409
Leakage Rate	≤1×10⁻⁴ mbar·L/s (Gas - tight)	ISO 15848
Friction Coefficient (Dry State)	0.1–0.3	ASTM D2714