I have no practical experience, but colloidal silicon dioxide might be suitable.

Pyrolytic Boron Nitride (PBN) Crucible is a highly pure, crystalline form of boron nitride that is produced through a chemical vapor deposition (CVD) process. Compared with standard boron nitride ceramic, PBN crucibles offer significantly higher purity. These crucibles and other PBN products are synthesized directly on molds using the CVD process, involving BCl3 and NH3 at high temperatures and low pressures. This precise method results in PBN products with a total impurity content of less than 100 ppm, equating to a purity level exceeding 99.99%. Due to this exceptional purity, PBN crucibles are highly suitable for use in the semiconductor industry.

Common laboratory crucibles include boron nitride crucible, pyrolytic boron nitride crucible, etc. The crucible is an invaluable part of the laboratory gear, and they're expensive as well. Once you are done conducting your experiments, you need to know how to maintain crucibles effectively and without causing damage to the crucible surface so they can be used again.

How to Clean the Crucible?

Cleaning chemicals from ceramic crucibles is relatively easy. Therefore, ceramic crucibles are usually preferred for lab men. You will only need a few basic chemicals and supplies to do that.

Step 1: Gently scrape as much residue left from the materials used in your experiment from the crucible.

Step 2: Fill your ceramic crucible with fused potassium bicarbonate (solid form). You should have enough bicarbonate in the crucible to past above the line of the remaining material from your experiments. If you need to fill the entire crucible, do so.

Step 3: Place the crucible on a burner. Heat the crucible until the fused bicarbonate melts. Heat it until a layer of red potassium salt appears on the surface. Using a mixing rod, stir the melt a few times. The entire melting procedure should take about one minute.

Step 4: Remove your crucible from the flame. Pour out the melt.

Step 5: Rinse the crucible in hot water. Use a clean cloth to dry the surface. If your crucible is platinum, use alumina-impregnated nylon webbing to complete cleaning the surface. Let the crucible cool.

Conclusion

Thank you for reading our article and we hope it can help you to have a better understanding of the use of ceramic crucibles and how to clean them.

Dear Muhammad,

Boron nitride powder cannot be sintered at 1000°C, so it is natural that it remains powdery. No continuous coating of BN with good adhesion to ceramics can be obtained in this way.

However, boron nitride powder can be rubbed (brushed or fingered) into the inner surface of a corundum crucible so that a thin powder layer can act as a non-stick coating. When working in a protective environment, the same can be done with graphite powder.

I think that colloidal silicon dioxide should be applied to the corundum first, followed by boron nitride. I think the coating will be durable.

Thank you so much Mr. Garegin Zakharov , Dr. Vadim Verlotski and Dr. Paul Olaru for your fast and insightful responses.