High-Purity Alumina Ceramic Seal Ring for High-Temperature Chamber Sealing

St.Cera‘s ceramic seal ring is designed as an alternative to polymer O-rings in extreme environments where elastomers degrade. Manufactured from 99.8% high-purity alumina (Al₂O₃), this rigid seal ring is used in static sealing applications — typically paired with a soft metal or graphite gasket — to provide reliable vacuum or gas containment at temperatures up to 800°C and in aggressive plasma or chemical environments. The material offers zero outgassing, high compressive strength (underlying flexural strength 361 MPa), and chemical inertness (resistant to halogens, acids, and alkalis except HF). Precision-lapped sealing surfaces (flatness ≤5 μm, surface roughness Ra ≤0.2 μm) ensure leak-tight contact with mating metal or ceramic components.

Specifications (based on 99.8% Al₂O₃):

Applications:

• · Semiconductor process chamber static seals (CVD, PVD, etch)
• · High-temperature furnace door seals
• · Vacuum feedthrough flanges
• · Chemical reactor vessel closures

Manufacturing Process:

Isostatic pressing → sintering at 1600°C → precision double-side lapping to achieve ultra-flat, smooth sealing faces → edge chamfering → ultrasonic cleaning. Each ring is 100% leak-tested on a helium leak detector with a standard metal gasket.

Quality Control:

• · CMM dimensional check (ID, OD, thickness, parallelism)
• · Surface profilometer for Ra and waviness
• · Flatness measurement using optical flat
• · Helium leak test (back-pressurization method)

Advantages over Polymer O-rings:

• · Withstands 800°C vs. <300°C for FFKM
• · Zero outgassing — no contamination of vacuum environment
• · Resistant to all plasma chemistries (fluorine, chlorine, oxygen)
• · No compression set or permanent deformation
• · Unlimited service life in clean environments

Limitations (Critical Remarks):

• · Not an O-ring — it is a rigid ceramic ring that requires a soft gasket (copper, aluminum, or graphite) to seal.
• · Does not accommodate dynamic motion or large flange misalignment.
• · Higher initial cost than polymer O-rings, but longer lifetime reduces cost of ownership.
• · Brittle — handle with care; avoid point impact or bending stress.

Note: The data above strictly follows the supplied Al₂O₃ property table. No data for elastomeric materials was provided. This product is a static seal ring, not an elastomeric O-ring. Please confirm whether this meets your application requirements.