Silicon Nitride Crucible for Aluminum, Magnesium and Zinc Melt Processing

Si3N4 Ceramic Crucible Applications

• Aluminum Casting & Foundry Cells

  ✅Key Advantages

  1. Extended Casting Cycles Without Metal Wetting
  Silicon nitride crucibles maintain non-wetting behavior in Al-Si melts, enabling 200–450 casting cycles before replacement when preheated to 850 °C prior to metal contact.

  2. Dimensional Consistency Reduces Robot Alignment Errors
  With controlled tolerances (±0.2 mm ID/OD), the crucible seats accurately in LPDC fixtures and supports automated ladling arms with <1 mm clearance.

  3. Lower Dross Accumulation Improves Melt Cleanliness
  Smooth inner surface (Ra ≤ 1.6 µm) reduces aluminum oxide buildup by up to 30%, keeping molten metal contact cleaner and decreasing inclusion defects in castings.

  ✅ Problem Solved

  A Tier-2 automotive casting plant using AlSi9Cu3 switched from graphite to silicon nitride crucibles in its low-pressure casting cells.
  Cycle life increased from an average of 120 pours to 340 pours per crucible under a controlled preheat of 300 °C → 900 °C → 750 °C standby.
  Robot arm misalignment alarms due to lip wear dropped from 8 per week to less than 2 per month.
  Scrap rate caused by dross inclusions decreased from 2.6% to 1.3%, and the furnace downtime for cup replacement was reduced by approximately 28%.

• Vacuum & Atmosphere Furnace OEM

  ✅Key Advantages

  1. Stable geometry across heating cycles enables precise furnace alignment
  Silicon nitride crucibles maintain roundness deviation within ≤0.15 mm after repeated heating to 1300 °C in N₂ atmosphere, ensuring consistent fixture positioning.

  2. Low gas permeability reduces contamination in controlled atmospheres
  Open porosity below 1% prevents hydrogen or nitrogen infiltration into the melt, keeping aluminum and magnesium alloys free from gas porosity defects.

  3. Compatible with robotic loading systems in OEM-integrated furnaces
  Custom lip and shoulder profiles with ±0.2 mm tolerance support automated crucible placement with less than 0.5 mm clearance tolerance in machine loaders.

  ✅ Problem Solved

  A European furnace OEM supplying vacuum alloy testing systems replaced alumina crucibles with silicon nitride models to address deformation and leakage during thermal cycling.
  In 50-unit pilot production, silicon nitride crucibles held dimensional accuracy after 60 heating cycles up to 1350 °C in argon, while alumina units showed >0.4 mm warping and microcracking.
  Gas inclusion in Al-Mg alloy samples dropped by 35%, and no metal leaks were recorded across the testing series.
  The OEM standardized one crucible geometry instead of the three previous models, reducing machining time by 22% and simplifying spare part logistics.

• Materials Laboratory & Alloy Research

  ✅Key Advantages

  1. Small-volume melting with high mass precision
  Silicon nitride crucibles allow alloy melting in 20–200 ml ranges with mass deviation typically within ±1.5% across repeated heating and pouring cycles.

  2. Low contamination during alloy composition testing
  Si₃N₄ does not release carbon or oxygen into Al-Mg-Ti melts, keeping impurity levels below 0.02 wt%, which is critical for metallographic and DSC/TGA samples.

  3. Surface finish supports repeatable sample decanting
  Polished inner surface (Ra ≤1.6 µm) enables clean metal flow and reduces residue buildup, ensuring consistent sample retrieval and easier post-test cleaning.

  ✅ Problem Solved

  A university materials lab conducting Al–Mg–Sc alloy trials reported inconsistent test results when using graphite crucibles due to carbon pickup and mass loss during decanting.
  After switching to 80 ml silicon nitride crucibles, sample weight variation reduced from ±3.8% to ±1.2% over 15 test runs.
  Elemental contamination from the crucible fell below 0.02 wt% (verified via ICP-OES), and no carbon or oxygen inclusion rings appeared in metallographic sections.
  Cleaning time between tests was reduced by 40%, as molten alloy no longer adhered to the crucible wall after solidification.

Silicon Nitride Crucible Usage Instructions

• Installation

  1. Check the crucible pocket size, support ring or seating surface before heating. Dry-fit the crucible to verify stability and avoid tilting or lip stress.
  2. Measure ID/OD and base flatness against the drawing during incoming inspection to confirm dimensional tolerance and robotic pickup compatibility.
  3. Avoid direct metal-to-metal contact between the crucible edge and the steel support; use insulating pads if specified by the furnace manufacturer.

• Pre-heating & Use

  1. For first use, heat gradually: 20 °C → 300 °C (hold 30 min), 300 °C → 800–900 °C (hold 30 min), then approach operating temperature. This avoids thermal shock and microcracks caused by sudden temperature gradients.
  2. Use a diffuser, burner screen, or indirect heating to prevent direct flame impact on the crucible base or walls, which causes localized overheating.
  3. Once molten metal is introduced, keep skimming oxides to prevent dross buildup and avoid letting aluminum freeze inside the crucible, as solidified alloy can exert expanding stress and crack the walls.

• Storage

  1. Store the crucible in a dry, ventilated room with desiccant, especially after sea or winter transport, to avoid moisture absorption that can cause steam pressure cracks during reheating.
  2. Keep lids and crucibles paired by batch to maintain proper lip contact and sealing performance, especially when used in a nitrogen or argon atmosphere.

• Cleaning

  1. Clean while the crucible is still warm (not hot) using non-metallic tools to remove dross or metal films without scratching the surface.
  2. Do not immerse a hot crucible in water or place it on a cold steel plate; rapid cooling will cause internal thermal stress and reduce cycle life.
  3. For polished inner surfaces (Ra ≤1.6 μm), use soft scrapers or fiber brushes to preserve smoothness and prevent microabrasion that increases melt adhesion.

• User Errors & Prevention

  Issue	Cause	Prevention
  Cracking on first heat-up	Heated directly to 700 °C from room temperature	Use staged pre-heating as specified above
  Crucible stuck to furnace base	Molten aluminum seeped and solidified under cup	Use proper insulating ring and remove frozen metal before cooling completely
  Robot misalignment alarm	Lip deformation or size drift after cycles	Inspect lip diameter periodically; replace when deviation exceeds design tolerance

Silicon Nitride (Si3N4 ) Crucible FAQ

1. Q: What is a silicon nitride crucible used for in aluminum casting?
   A: A silicon nitride crucible, also called a Si₃N₄ ceramic crucible, is used to melt, hold or sample aluminum and magnesium alloys in foundry cells, furnace systems and laboratory test setups where low wettability and stable cycle life are required.
2. Q: How many casting cycles can a silicon nitride crucible typically withstand?
   A: In aluminum foundries, silicon nitride crucibles from reliable manufacturers can last 200–450 cycles, depending on alloy, preheating and handling conditions.
3. Q: Where can I find silicon nitride crucible for sale or wholesale purchase?
   Silicon nitride crucibles for sale can be sourced directly from a silicon nitride crucible factory or manufacturer in China if you require OEM sizes, bulk purchasing or wholesale pricing.
4. Q: Do you offer silicon nitride crucible made in China with factory customization?
   A: Yes, China Si₃N₄ ceramic crucible manufacturers, such as ADCERAX, provide drawing-based production for different furnace models and accept custom dimensions with ±0.2 mm tolerances
5. Q: Can silicon nitride crucibles be used in laboratory research?
   A: Yes, laboratory use Si₃N₄ crucibles are widely used for DSC analysis, small-volume melting and metal decanting in research institutes and university material labs.
6. Q: Does molten aluminum stick to silicon nitride crucibles?
   A: No, silicon nitride ceramic crucibles show very low wettability to Al/Mg melts; this is why many buyers switch from graphite crucibles to Si₃N₄ crucibles to reduce dross adhesion.
7. Q: Can I order a silicon nitride coating crucible or coated version?
   A: Yes, some manufacturers offer silicon nitride coating crucibles or Si₃N₄-coated graphite versions for specific melt chemistries, but full silicon nitride crucibles are preferred for longer service life.

Customer Reviews — Silicon Nitride Crucible

• ⭐️⭐️⭐️⭐️⭐️
  We tested silicon nitride crucibles from several suppliers, but the batches from the Chinese manufacturer we work with now lasted over 300 casting cycles in our LPDC cells. The non-wetting surface reduced aluminum buildup and our changeover time dropped noticeably.
  -- Michael Turner | Production Supervisor | AlloyCast Foundry, USA
• ⭐️⭐️⭐️⭐️⭐️
  We needed a custom Si3N4 ceramic crucible with a 148 mm ID and ±0.2 mm tolerance for our automated furnace loader. The factory in China adjusted the lip profile according to our drawing and the crucibles fit correctly without rework.
  -- Sara Müller | Procurement Manager | G-Tech Furnace Systems, Germany
• ⭐️⭐️⭐️⭐️⭐️
  For laboratory use, we ordered 80 ml Si3N4 crucibles for alloy testing. The mass repeatability improved compared to graphite cups because there was no carbon contamination. They clean easily, which is important when running multiple DSC or melt trials in one day.
  -- Dr. Kenichi Sato | Materials Lab Engineer | Osaka Technical Institute, Japan
• ⭐️⭐️⭐️⭐️⭐️
  We purchase wholesale silicon nitride crucibles for our aluminum recycling line. Pricing from the manufacturer is stable, and delivery from the China-based factory is consistent. Even after several shipments, the dimensional quality and cycle life have been reliable.
  -- Luis Hernández | Purchasing Director | Metal Reclaim Solutions, Mexico