Searching for fully sintered boron nitride ceramic

[gwj0606]

TL;DR Summary

Anyone can supply slightly yellow, fully sintered boron nitride ceramic?

I understand that boron nitride has quite high sintering temperature so it is not easy and could be quite expensive to get fully sintered material. But there are something available, right? I think I saw a small smaple of lilght yellow boron nitride ceramic years ago, but I don't remember the manufacturers name. It was quite smooth and semi-transparent, like alumina(I'm quite sure it's not PBN, because it's a block of about 1" cube). I believe it should be a fully sintered one. However, the BN I recently obtained are quite white, not transparent, and can be scraped off into powder. I guess it should be semi-sintered material, not fully sintered.

My job is now working on a quite big crucible like parts, that requires about 200mm Dia. x 400mm L in size. We puchased some [Link redacted by the Mentors], as they are the only one we found that could make such big parts. The parts are acceptable but, like what I said, they are more like a semi-sintered material. I was wondering is there anyone knows who can supply the fully sintered material? And, the maximum size available?

 

[Tom.G]

from:
https://www.nature.com/articles/s41467-019-08580-9

...it is currently impossible to sinter hBN powder to a dense bulk (with a relative density of above 96%) even at 2000 °C.

(above found with:
https://www.google.com/search?hl=en&q=sintered+boron+nitride+shapes)

For more technical results, try:
https://scholar.google.com/scholar?hl=en&q=sintered+boron+nitride+shapes

You could also try a search phrase of:
strength of sintered borin nitride

Cheers,
Tom