Silicon Nitride Seal Rings for Drawing-Based Sealing Assemblies

Silicon nitride seal rings with drawing-defined bores, locating features and single- or double-lapped working faces.

Catalogue No. AT-DHG-MF001
Material Silicon Nitride
Flexural Strength 700 MPa (typical, material value)
Face Finish & Flatness Confirmed per drawing at RFQ review
Dimensions/Sizes Download PDF
Engineering RFQ Review
Small-Batch Custom Support
Drawing-Based Production
Drawing & Process Review

A silicon nitride seal ring is a precision-machined Si₃N₄ ceramic ring used as a rotating or stationary seal face in mechanical seals and in static or vacuum sealing assemblies. Its job is to hold a stable sealing interface under pressure, temperature change, and sliding contact, where metal faces wear or distort.

Specifications of Si3N4 Seal Ring

size for ring

Item Outer Diameter (mm) Inner Diameter (mm) Thickness (mm)
AT-DHG-MF001 10.0  5.0  2.5 
AT-DHG-MF002 15.0  9.0  3.0 
AT-DHG-MF003 20.0  12.9  3.5 
AT-DHG-MF004 25.0  15.0  2.0 
AT-DHG-MF005 28.0  20.0  2.5 
AT-DHG-MF006 31.0  25.0  3.0 
AT-DHG-MF007 36.5  27.0  4.5 
AT-DHG-MF008 48.0  38.0  4.8 
AT-DHG-MF009 50.0  39.0  5.0 
AT-DHG-MF010 50.0  40.0  5.0 
AT-DHG-MF011 50.0  38.5  5.5 
AT-DHG-MF012 50.0  30.0  10.0 
AT-DHG-MF013 51.0  40.5  5.1 
AT-DHG-MF014 55.5  51.5  2.0 
AT-DHG-MF015 62.0  51.0  5.5 
AT-DHG-MF016 65.0  53.8  5.5 
AT-DHG-MF017 68.0  57.0  5.5 
AT-DHG-MF018 90.0  18.0  6.0 
AT-DHG-MF019 102.0  63.0  19.4 
AT-DHG-MF020 120.0  112.8  8.5 
AT-DHG-MF021 1-150 0.5-140 0.25-50

Download Size Guide

Silicon Nitride Seal Ring Material Properties

ADCERAX silicon nitride seal rings are machined from the AD-SIN-ST structural ceramic grade. The values below are material data from our current official datasheet, measured on sintered material rather than on a finished ring.

Property Unit / Condition AD-SIN-ST Value
Product form Sintered ceramic Tubes, rotors, rings, and machined structural parts
Bulk density g/cm³, typical 3.2
Flexural strength MPa, typical 700
Fracture toughness KIC MPa·m½, method-dependent 6.5
Thermal conductivity W/(m·K), typical 20
Apparent porosity vol%, sintered body <0.3
Poisson's ratio –, typical 0.25
Rockwell hardness HRA, typical 92–94

How to Specify a Silicon Nitride Seal Ring

Start with the information you have. ADCERAX helps confirm missing details during drawing review.

1. Sealing Duty

Identify the ring as a rotating face, stationary face, or static/vacuum sealing component. Include the equipment model, seal type and replacement part number if available.

2. Dimensions and Seal Face

  • Geometry: OD, ID, thickness, face width, steps, grooves and drive features.
  • Seal face: Required flatness, parallelism and surface finish.
  • Edges: Chamfer or radius dimensions to help prevent installation damage.

Mark these requirements on the drawing for review.

3. Counterpart Material

Specify the mating material: silicon carbide, tungsten carbide, carbon graphite or Si₃N₄. If unsure, share your operating conditions so ADCERAX can review the pairing.

4. Operating Conditions

  • Dynamic seals: Media, particles, pressure, shaft speed, temperature and flushing or cooling.
  • Vacuum seals: Target vacuum, allowable leak rate, test method, cleanliness and bake-out requirements.

Vacuum performance requirements are verified at assembly level.

5. Two-Step Quotation

  • To start: Send a drawing or main dimensions, media and quantity. Worn samples or clear photos can help when drawings are unavailable.
  • Before quotation: Confirm the counterpart material, operating conditions and inspection requirements with ADCERAX.

Silicon Nitride vs SiC vs Tungsten Carbide Seal Rings

Most seal face decisions come down to silicon nitride, silicon carbide, or tungsten carbide, with carbon graphite as the usual soft counterpart rather than a competing hard face. The differences that matter in service:

Material Key Advantage Limitation Best Fit
Silicon Nitride (Si₃N₄) Low density, high fracture toughness, and good thermal shock resistance Requires a matched counterpart and precision-lapped faces High-speed, start-stop, dry gas, and vacuum sealing assemblies
Silicon Carbide (SiC) High hardness and excellent chemical resistance Less forgiving of impact and shaft misalignment Abrasive slurries, aggressive chemical pumps, high-wear pairs
Tungsten Carbide (WC) High strength and tolerant of rough handling Roughly twice the density of Si₃N₄; metal binder can corrode in some media Heavy-duty oil, water, and general mechanical seal systems
Carbon Graphite Self-lubricating; gentle on the opposing face Wears faster than ceramic faces; lower overall strength Soft counterpart face in dry gas, vacuum, and low-lubrication pairs

 

Si3N4 Seal Ring Packaging

  • Clean room-grade pouch → anti-static tray → foam-lined carton. Single-piece separators prevent face rub.

Si3N4 Seal Ring Packaging

Silicon Nitride Seal Ring Applications

ADCERAX supplies the ceramic rings and seal faces used inside these systems — as OEM production parts or as replacements made from drawings or worn samples. We supply the rings themselves, not complete cartridge seal assemblies; if you need a full seal unit, your seal maker remains the right contact, and we can supply the faces to their drawings.

  • Process Pumps & Compressors

    The sealing problem: seal faces wear, chip at the edges, or drift out of flat under slurry, chemical media, and repeated start-stop cycles — and every unplanned seal change is pump downtime.
    What ADCERAX supplies: rotating and stationary Si₃N₄ faces lapped to the agreed flatness band, with edge chamfers designed for field installation, in catalog sizes or to your seal maker's drawing.

  • Vacuum Pumps & Dry Gas Seals

    The sealing problem: dry and low-lubrication duty raises start-up friction and heat, and vacuum systems add cleanliness and leak-rate expectations that ordinary wear parts are never checked against.
    What ADCERAX supplies: precision-lapped Si₃N₄ rings for dry gas and vacuum sealing assemblies, commonly paired with carbon graphite or SiC counterparts; cleanliness steps and leak-rate verification at assembly level are agreed at order review rather than assumed.

  • Mixers & Agitators

    The sealing problem: shaft misalignment, axial run-out, and particles in the media load seal edges unevenly and open leak paths long before the face itself is worn out.
    What ADCERAX supplies: rings with controlled chamfer, face width, and flatness that give the assembly more tolerance to real-world alignment, plus pairing advice when the media carries solids.

  • Rotating Equipment OEM Assemblies

    The sealing problem: serial production needs repeatable ID/OD, face parallelism, and batch-to-batch consistency — a ring that measures differently each delivery breaks the assembly line, not just the seal.
    What ADCERAX supplies: drawing-based production with agreed inspection points and dimensional reports per batch, so repeat orders arrive to the same geometry as the first article.

How to Specify a Silicon Nitride Seal Ring

To specify a silicon nitride seal ring, engineers should confirm the ring geometry, mating material, sealing media, operating temperature, pressure-velocity condition, lubrication state, and required face finish. ADCERAX reviews drawings, samples, and application conditions before quotation to help match the Si₃N₄ ring design with the actual sealing environment.

Specification Item What to Confirm Why It Matters
ID / OD / Thickness Drawing dimensions, tolerance range, and assembly clearance. Ensures the ring fits the seal housing and shaft design.
Face Width Contact track width and counterpart face size. Affects sealing film stability and friction behavior.
Flatness / Parallelism Required inspection band based on seal duty. Helps control leakage risk and uneven face loading.
Surface Finish Ra / Rz range and lapping direction. Influences run-in, fluid film formation, and friction.
Counterpart Material SiC, carbon graphite, tungsten carbide, or Si₃N₄. Determines wear pairing and thermal compatibility.
Media Condition Liquid, gas, slurry, solvent, or vacuum environment. Helps judge corrosion, particle, and lubrication risks.
Edge Design Chamfer, radius, groove, or notch requirements. Reduces chipping during installation and operation.

Silicon Nitride Seal Ring Usage Instructions

These are handling practices for ceramic seal faces. Operating limits — pressure, speed, PV, temperature, and leakage criteria — belong to your seal design and are confirmed there, not taken from a general product page.

  • Installation

    1. Check the seat bore, shaft run-out, and seat flatness against the seal design values before the ring goes in; uneven contact loads the face and the edge.
    2. Keep face protectors on until the ring is seated, and never let the lapped face touch metal or another face. Clean gloves prevent scratches and oil contamination.
    3. Use the alignment sleeves or jigs supplied with the seal design, and set spring compression or preload to the design value.
    4. Tighten gland bolts diagonally and in stages so clamping stays even around the ring.

  • Operation

    1. Stay within the pressure, speed, and temperature window of the seal design, and keep flush or barrier systems running as designed — dry running is the fastest way to destroy any ceramic face.
    2. Watch start-stop frequency, vibration, and leakage trend during commissioning; a rising leakage trend is the early warning worth acting on.
    3. For dual seals, maintain the barrier fluid condition specified by the seal maker.

  • Storage and cleaning

    1. Store rings individually in their pouches or padded trays, faces protected, in a clean dry place; never stack faces together.
    2. Clean with filtered solvent or deionized water and lint-free wipes; no abrasive cloths, wire brushes, or aggressive acid/alkali agents on the lapped face.
    3. Dry with clean, oil-free air. If a ring has been stored long-term, re-inspect the face before assembly.

  • If something goes wrong

    1. Chipped edge found at assembly: stop and replace the ring if the chip touches the contact band; review edge chamfer and installation tooling before the next fit.
    2. Early leakage at commissioning: recheck seat flatness, clamping evenness, and preload against the seal design before blaming the face.
    3. Heat marks or discoloration on the face: evidence of dry running or lost flush — restore the fluid film first; re-lapping may recover the ring if damage is shallow, which ADCERAX can assess from photos.

Silicon Nitride Seal Ceramic Ring FAQ

  1. Q: What is a silicon nitride seal ring used for?
    A: It works as a rotating or stationary ceramic seal face in mechanical seals for pumps, compressors, mixers, and rotating equipment, and as a sealing ring in static or vacuum assemblies. It is chosen where metal faces wear, corrode, or lose flatness in service.
  2. Q: How should silicon nitride seal rings be paired with counterpart materials?
    A: Si₃N₄ faces run against silicon carbide, tungsten carbide, carbon graphite, or another Si₃N₄ ring. As a starting point: carbon counterparts suit dry gas and vacuum duty, SiC suits abrasive and chemical media, and tungsten carbide suits heavy-duty oil and water services. ADCERAX confirms the pairing with your media, pressure, and speed at engineering review.
  3. Q: What face finish and flatness should be specified for a silicon nitride seal ring?
    A: Flatness, parallelism, and surface roughness for the contact band are set by the seal design — duty, media, speed, and counterpart material all move the target, so there is no single correct number. Put your required values on the drawing; ADCERAX confirms them at review and laps the face to the agreed band, with inspection records available on request.
  4. Q: Does low porosity mean a silicon nitride seal ring is vacuum-tight?
    A: No. Apparent porosity below 0.3 vol% describes the sintered material, not the finished assembly. Vacuum tightness and helium leak rate depend on the finished faces, surface condition, mating parts, and the whole sealing interface, and are verified by testing at assembly level. State your target vacuum level and leak-rate requirement in the RFQ so verification is agreed up front.
  5. Q: Can ADCERAX customize the ID, OD, and face finish?
    A: Yes. ADCERAX supports drawing-based ID, OD, thickness, face width, chamfer, groove, flatness, and surface finish customization for OEM and MRO sealing assemblies, in catalog sizes and made-to-order dimensions.
  6. Q: What information is needed for quotation?
    A: To start: a drawing or the main dimensions, the sealing media, and the quantity — a worn sample or clear photos work when no drawing exists. At engineering review, ADCERAX confirms counterpart material, operating conditions, and any flatness, finish, or leak-rate requirements before issuing the quotation.
  7. Q: How are silicon nitride seal rings inspected?
    A: Against the agreed drawing: dimensional checks, face flatness and finish verification on agreed items, visual inspection of edges and surfaces, and a packaging review before shipment. Inspection scope and reports are agreed at order level.
Silicon nitride seal ring diagram showing outer and inner diameters, thickness, sealing face width, stepped profile, alignment notches and edge details.

Custom Silicon Nitride Seal Ring

ADCERAX manufactures AD-SIN-ST silicon nitride seal rings to drawing or sample. Dimensions, surface finish and inspection requirements are confirmed before quotation.

1. Dimensions
Custom sizes cover OD 1–150 mm, ID 0.5–140 mm and thickness 0.25–50 mm. Tolerances depend on ring size and geometry. Other sizes are reviewed individually.

2. Seal Face
Single- or double-face lapping is available, with flatness, parallelism and surface finish specified for the contact band. Inspection records can be included.

3. Geometry Features
Chamfers, radii, steps, grooves, drive slots and alignment marks can be customized. Webbed, slotted or split-ring designs require drawing review.

4. Material Pairing
Pairing with SiC, or Si₃N₄ is reviewed against your media, pressure and speed.

5. Marking and Inspection
Options include part labeling. Dimensional and seal-face inspections follow the agreed drawing requirements before shipment.

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