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Seal Material Comparison

Views: 0     Author: Site Editor     Publish Time: 2025-08-18      Origin: Site

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Property

Ceramic

Graphite

NBR Rubber

Hardness

HV 1500-2000 (Mohs 9)

HB 50-80 (self-lubricating)

Shore A 70-90

Max Temp(℃)

1500 (oxidizing)

450 (air) / 3000 (vacuum)

-40~120 (peak 150)

Friction Coeff

0.1-0.3 (lubricated)

0.08-0.15

0.3-0.6 (dry)

Chemical Res

All chemicals (except HF)

Strong acids/solvents

Oil/water (fails in ketones)

Compression Rate

0% (rigid)

5-15%

15-30%

Applications

High-speed pumps, rockets

High-temp reactors

Automotive pumps, food machinery

Failure Mode

Brittle fracture

Oxidation (>400℃ air)

Swelling/cracking

Cm-A (1)副本

Technical Insights

1. Ceramic Seals (Al₂O₃/SiC)

Pros:

Extreme wear resistance (5x life in sand)

Zero leakage (flatness ≤0.3μm)

Cons:

Thermal shock failure (ΔT>200℃/min)

Demands precision installation

Solutions:

SiC-tungsten composite:Impact resistance ↑300%

Bellows compensation:Absorb misalignment

2. Graphite Seals

Key Features:

Self-healing surface (tolerates Ra≤1.6μm)

Electrical conductivity (5-30μΩ·m)

Enhanced Types:

Resin-impregnated:Phenolic (acid-proof) / Furan (alkali-proof)

Carbon-fiber reinforced:Compressive strength →120MPa

Avoid:

Fuming HNO₃ / liquid oxygen

High-speed rotation (>30m/s)

3. NBR Seals

Advantages:

Elastic sealing (compensates ±0.5mm vibration)

Low cost (1/50 of ceramic)

Chemical Limits:

Max swelling:

Gasoline: ≤15% vol. expansion (>20% fails)

Benzene solvents: Prohibited

Ozone cracking:>0.1ppm in air

Upgrades:

HNBR:Temp→150℃ / ozone resistance ↑10x

PTFE coating:Friction coeff. →0.05



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