Custom Boron Nitride Crucible for High-Temperature, Non-Wetting Processes

Custom Boron Nitride Crucible Applications

Custom boron nitride crucibles are used where metal wetting, atmospheric contamination, or dimensional shift cannot be tolerated. They function not only as containers but as part of the thermal system—often integrated into vacuum chambers, induction coils, or coating fixtures.

• Vacuum Furnace & High-Temperature Thermal Processing

  Typical Uses： Brazing fixtures, heat treatment, sintering of reactive alloys, thermal evaporation crucibles in vacuum or inert gas.✅Key Advantages

  1. Dimensional accuracy for sealed fixtures — stepped rims or flat sealing surfaces ensure reliable contact with graphite or molybdenum hot zones.
  2. Low outgassing (<10⁻⁵ Pa) — prevents pressure instability and contamination inside high-vacuum chambers.
  3. Thermal stability up to 1800–1900 °C — no grain swelling or softening in prolonged high-temperature cycles.

  ✅ Problem Solved

  A German furnace builder adopted BN crucibles with 0.10 mm lid step tolerance for titanium alloy annealing. Gas leakage dropped by 35%，and furnace restart time shortened by 20% due to reduced chamber contamination and easier cleaning.

• Molten Aluminum /Magnesium/Precious Metal Handling

  Typical Uses： Alloy sampling cups, casting crucibles, melt holding vessels, refining containers.

  ✅Key Advantages

  1. Non-wetting to Al/Mg alloys — contact angle > 120°, reducing slag adhesion and improving pour yield.
  2. Prevents iron and silica contamination — unlike steel or silica crucibles, BN does not dissolve into molten metals.
  3. Electrical insulation for induction melting — isolates molten metal from induction coils without eddy current loss.

  ✅ Problem Solved

  An Italian die-casting workshop replaced Al₂O₃ crucibles with BN for Mg alloy sampling. Metal residue decreased by 40%，sampling time reduced by 1.5 minutes/pour, and sample surface clarity improved significantly for spectrographic analysis.

• PVD/CVD Coating, Thin Film Deposition & Semiconductor Adjacent Processes

  Typical Uses: Crucibles for evaporation materials, target melting, protective containers for precursor chemicals, coating batch holders.

  ✅Key Advantages

  1. Low vapor pressure & chemical inertness — prevents BN material evaporation into chambers <10⁻⁶ Torr.
  2. No alkali/alkaline contamination — avoids Na⁺, K⁺ ion pollution that commonly damages optical coatings or hard films.
  3. Complex geometry for fixture integration — ports for thermocouples, angled grooves for vapor flow, lid alignment pins all machinable in BN.

  ✅ Problem Solved

  A Korean PVD tool manufacturer used BN crucibles to load Ti/Al/Cr targets. Chamber particle count dropped by 28%，coating uniformity improved from ±6% to ±3.5%，and chamber cleaning interval extended from 60 hours to 96 hours.

Custom BN Crucible Usage Instructions

This guide helps users correctly install, operate, maintain and extend the service life of custom boron nitride crucibles in vacuum, inert, or molten metal applications.

• Installation & Pre-Use Preparation

  1. Check fit and geometry: Verify ID/OD, mating lid, step height, and sealing surfaces match the furnace fixture or support plate before heating.
  2. Pre-bake to remove moisture: Heat slowly to 200–300 °C in air or inert gas for 1–2 hours to remove adsorbed water. This prevents microcracking and outgassing under vacuum.
  3. Avoid excessive force: BN is machinable but brittle; do not press-fit or hammer into holders. Use graphite, molybdenum, or BN support rings if required.
  4. Lid alignment: Ensure orientation marks match. If a stepped or tongue-and-groove lid is used, check for smooth engagement without binding.

• Operating Guidelines

  1. Heating rate: For wall thickness ≤3 mm, limit ramp rate to ≤5 °C/min; thicker walls can handle 5–10 °C/min. Rapid heating can cause internal stress cracking.
  2. Atmosphere control: Use under vacuum or inert gas (Ar/N₂). Continuous exposure to air above 900–1000 °C leads to oxidation of BN and surface whitening.
  3. Molten metal contact: Preheat crucible before adding metal to avoid thermal shock. For Al/Mg melts, maintain crucible temperature within ±20 °C of the melt to stabilize non-wetting behavior.
  4. Induction or resistance heating: BN is electrically insulating—safe for contact near coils. However, ensure metal does not overflow and form a conductive bridge.

• Cooling & Post-Processing

  1. Controlled cooling: Cool under inert atmosphere or in furnace chamber. Avoid forced air cooling or cold plate contact that creates thermal gradients.
  2. Do not quench: Direct immersion into water/oil or rapid gas cooling causes cracking due to low thermal expansion mismatch.
  3. Lid removal: Allow crucible to reach <100 °C before attempting to remove the lid; residual thermal expansion may cause binding.

• Cleaning & Maintenance

  1. Residue removal: Use soft brush or compressed air. For metal residues, gently scrape using a plastic or BN tool; avoid steel tools.
  2. Chemical cleaning: Use only non-reactive solvents. Avoid acids or alkalis that can attack BN or leave ionic contamination.
  3. Surface reconditioning: Slight surface glazing or metal films can be sanded with 600–1000 grit SiC paper; remeasure dimensions if tolerance is critical.
  4. Storage: Store in a dry cabinet or sealed PE bag with desiccant. Keep lids paired with corresponding crucibles to avoid mismatch.

• Common Issues & Solutions

  Issue	Possible Cause	Solution
  micro-cracks after first use	heated too fast, no pre-bake	use preheating cycle, reduce ramp rate
  lid stuck or warped	thermal expansion mismatch, uneven heating	increase lid clearance by 0.05–0.1 mm or refine heating profile
  metal wetting or sticking	crucible too cold, contaminated surface	preheat crucible; clean or polish inner surface
  vacuum level instability	residual moisture or surface dust	pre-bake at 200–300 °C; clean surface before chamber entry
  brittle edge breakage	direct tooling contact	use graphite or ceramic-handling tools

Custom Boron Nitride Ceramic Crucible FAQ

1. Q: What atmosphere is required when using a custom boron nitride crucible at high temperatures?
   A: A custom boron nitride crucible should be used in vacuum or inert gases such as argon or nitrogen when temperatures exceed 900–1000 °C. In air, BN will gradually oxidize, forming B₂O₃ on the surface, which evaporates or softens and may alter dimensions or contaminate the melt.
2. Q: Can a custom boron nitride crucible be used for molten titanium or reactive alloys?
   A: No. BN reacts with liquid titanium, hafnium, and high-activity rare earth alloys, forming TiB₂ or rare-earth borides. For these metals, Y₂O₃, CaO-stabilized ZrO₂, or graphite with coatings is preferred. BN is suitable for Al, Mg, Cu, Au, Ag, and most precious metals.

3. Q: What is the typical service life of a custom boron nitride crucible?
   A: Service life depends on melt temperature, cycling rate, and handling. In aluminum or magnesium alloy melting, a BN crucible can last 20–80 operating cycles. In PVD/CVD or vacuum heat treatment, it may exceed 100 cycles if thermal shock and contamination are controlled.

4. Q: How to prevent cracking in a boron nitride crucible during the first heat cycle?
   A: Pre-bake the crucible at 200–300 °C to remove moisture, then heat gradually at ≤5 °C/min until 600–800 °C. Sudden exposure to molten metal or rapid heating will cause tensile stress at the bottom and corners due to BN’s low thermal expansion and layered microstructure.

5. Q: Can boron nitride crucibles be reused after metal solidification?
   A: Yes, if metal residues are mechanically removed without scratching or chipping the wall. For Al or Mg, gently tapping or thermal cycling allows easy release due to non-wetting behavior. If residues remain bonded, inner wall polishing or replacement is recommended.

6. Q: Is machining internal threads or sharp edges possible in boron nitride crucibles?
   A: Threads are possible but only in low-stress, non-heated positions. BN is brittle compared to graphite; sharp internal corners should be replaced with 0.5–1 mm radii to reduce crack initiation. Thread pitch ≥1 mm and ≥3 mm wall thickness is recommended.

Custom Boron Nitride Crucible Reviews

• ⭐️⭐️⭐️⭐️⭐️
  We replaced alumina cups with a custom boron nitride crucible and ported lid. Coupon uniformity improved and chamber cleans decreased across two quarters.
  Elena Park — Process Engineer, Auron Coatings (DEU)
• ⭐️⭐️⭐️⭐️⭐️
  We ordered a custom boron nitride crucible from ADCERAX factory for our induction melting line. The dimensional accuracy and non-wetting surface helped us eliminate metal residue on the pouring lip, and after three production batches, we saw fewer interruptions and no need for manual scraping.
  Miguel R., Purchasing Manager, FerroCast Tools (USA)
• ⭐️⭐️⭐️⭐️⭐️
  The thin-wall BN crucible with lid helped shorten soak times for small alloy batches. Fit and finish were consistent over multiple shipments
  H. Nakamura — Materials Lab Lead, Saito Precision (JPN)
• ⭐️⭐️⭐️⭐️⭐️
  Using the custom boron nitride crucible simplified our pour routine due to its non-wetting behaviour. The price was not the lowest, but the stability of the crucible’s geometry reduced rework and saved significant line time.
  Laura S. — Operations Director, NordVac Systems (ITA)