Custom High-Purity Boron Nitride Crucible Liner – Non-Wetting, Anti-Contamination

Boron Nitride Crucible Liner Applications

• Vacuum Induction Melting of Titanium Alloys

  ✅Key Advantages

  1. Carbon pickup reduced from >0.04% to <0.01% by isolating titanium melt from graphite crucible
  2. Withstands 1600–1750 °C repeatedly without cracking under vacuum pressure cycles
  3. Maintains melt surface stability and prevents reaction with furnace atmosphere

  ✅ Problem Solved

  A titanium casting plant reported carbon contamination caused by direct use of graphite crucible, after replacing with boron nitride liners, oxygen and carbon impurities dropped by over 60%. The furnace could run 3 more cycles before crucible replacement, reducing per-batch material scrap and stabilizing alloy composition.

• Metal Powder Atomization for Additive Manufacturing

  ✅Key Advantages

  1. Keeps molten metal free from carbon or oxide inclusions during gas atomization
  2. Non-wetting surface enables full metal flow and improves powder sphericity (+5–8%)
  3. Reduces residue inside crucible, lowering cleaning and turnaround time

  ✅ Problem Solved

  A nickel-based alloy powder manufacturer experienced particle contamination from crucible erosion. Using BN liners eliminated contact reaction, increased powder purity from 99.3% to 99.7% and cut cleaning time from 4 hours to less than 1 hour per cycle.

• Precious Metal Melting in Laboratory & Small Furnaces

  ✅Key Advantages

  1. Silver and gold remain non-reactive to BN, allowing clean demolding and full recovery
  2. Protects graphite crucible from silver diffusion and thermal erosion
  3. Enables repeated use without slag adherence, reducing per-use cost

  ✅ Problem Solved

  A jewellery research lab reported gold residue sticking to graphite crucibles, losing 1–2 g per melt. Using BN liners eliminated adhesion, saved material loss and shortened equipment downtime.

Boron Nitride Crucible Liner Usage Guide

• Installation

  1. Inspect the graphite or ceramic crucible to ensure the inner surface is clean, smooth and free from cracks or debris before placing the BN liner.
  2. Gently lower the boron nitride liner into the crucible by hand; avoid using metal tools or hammering during positioning.
  3. If a stepped or flanged design is used, ensure the liner sits fully in contact with the seating surface—no gaps, tilting or stress points.
  4. For larger liners, it is recommended to preheat them to 100–150 °C to reduce moisture absorption before mounting.

• Operation

  1. Follow a gradual heating schedule to prevent thermal shock—recommended ramp speed ≤ 200–250 °C per minute up to 800 °C.
  2. Always operate under vacuum, argon or nitrogen atmosphere. Direct exposure to oxygen above 800 °C can oxidize or weaken the liner surface.
  3. When adding solid metal, preheat the feedstock or add slowly to prevent impact damage or cold spots.
  4. Do not scrape the inner wall with sharp tools during melting or pouring.
  5. After each melt, allow the liner to cool naturally inside the furnace. Avoid quenching or forced air cooling.

• Storage

  1. Store liners in a dry, dust-free cabinet. Relative humidity should be below 60% to prevent moisture absorption.
  2. For long-term storage, keep liners sealed in plastic bags with desiccant packs.
  3. Avoid stacking liners directly on top of each other—use foam or cloth layers to protect the edge and rim.

• Cleaning & Maintenance

  1. Remove residual metal only after the liner has fully cooled, using a soft plastic scraper or compressed dry air.
  2. If metal adheres to the surface, gentle sandpaper (≥ 800 grit) can be used; avoid deep grinding that may alter wall thickness.
  3. Do not immerse BN liners in water, acid, alkali or ultrasonic cleaning tanks.
  4. If fine powder or oxidation film appears, use dry alcohol wipes or vacuum cleaning only.

• Mistakes to Avoid

  Risky Practice	Possible Result
  Heating > 300 °C/min or uneven heating	Thermal shock, radial cracks
  Direct flame or oxy-fuel torch contact	Local oxidation and surface degradation
  Adding cold metal ingots in large pieces	Impact cracks or deformation
  Reusing liners with deep cracks or inner wall erosion	Alloy contamination or crucible leakage
  Pouring molten metal at too low a temperature	Incomplete flow, slag inclusion, blocked outlet
  Storing without moisture protection	BN absorbs moisture → micro-cracks during next heating

Crucible Liner Boron Nitride FAQ

1. Q: What is the main purpose of using a boron nitride crucible liner instead of a pure graphite crucible?
   A: A boron nitride liner creates a non-reactive barrier between molten metal and graphite, preventing carbon contamination, alloy carburization and metal adhesion. It is especially important when melting titanium, nickel-based, zirconium or precious metals that react easily with carbon at high temperatures.

2. Q: Can boron nitride crucible liners be reused, and how many cycles are typical?
   A: Yes. In vacuum titanium melting, a liner can usually be reused for 3–6 melting cycles, depending on alloy type, heating speed and wall thickness. If cracks or surface erosion appear deeper than 0.5 mm, reuse is not recommended.
3. Q: What furnace conditions are required for BN crucible liners? Can they be used in air?
   A: BN liners should be used under vacuum, argon or nitrogen atmospheres. Direct exposure to air above 800 °C causes BN oxidation. For long-term stability, furnace pressure should be ≤10⁻² Pa for vacuum or ≤0.1 MPa for inert gas protection.
4. Q: What are the typical tolerances and machining capabilities for custom BN liners?
   A: Inner and outer diameters can be controlled to ±0.1 mm, flatness within 0.05 mm, and concentricity ≤0.1 mm for small liners. For large liners (>200 mm OD), ±0.2 mm is standard due to material brittleness.
5. Q: How does a BN crucible liner affect alloy purity during melting?
   A: By isolating molten metal from graphite or metal crucible walls, BN liners reduce carbon absorption from 0.03% to <0.01% in titanium alloys and decrease inclusions formed from reactions with the crucible.
6. Q: Can BN liners be used for induction heating or only resistance furnaces?
   A: BN itself is electrically insulating, but it can be used inside induction furnaces when placed inside a graphite crucible that absorbs induction heating. The liner does not interfere with the electromagnetic field.
7. Q: What is the typical service life cost comparison vs. graphite crucibles?
   A: While BN liners cost more upfront, they extend graphite crucible life from 2–3 cycles to 5–7 cycles and reduce scrap metal from contamination, resulting in 20–35% lower total cost per melt for titanium or nickel alloy producers.

Customer Reviews about Boron Nitride Crucible Liner

• ⭐️⭐️⭐️⭐️⭐️
  We use boron nitride crucible liners for titanium melting. Purity is consistent and dimensions match our graphite crucibles precisely. ADCERAX provided drawings review before production.
  Martin Keller – Process Engineer, AeroMetall GmbH, Germany
• ⭐️⭐️⭐️⭐️⭐️
  Our atomization furnace requires customized BN liners. Delivery was on time, and the cost was lower than European suppliers. No carbon pickup detected in test batches.
  Sophia Lee – Purchasing Manager, KM Powder Metals, South Korea
• ⭐️⭐️⭐️⭐️⭐️
  The BN crucible liner prevented gold from sticking to graphite and improved material recovery. Easy to clean and no cracking after multiple cycles.
  David Chen – R&D Laboratory, SilverTech Jewellery Lab, USA
• ⭐️⭐️⭐️⭐️⭐️
  We switched to crucible liner boron nitride to reduce graphite contamination in Ni-based alloys. Surface quality of cast parts has clearly improved.
  Luca Romano – Production Director, AlloyCast Italy