Pyrolytic Boron Nitride deposition system 2

[ionsourcerer]

I need to coat and/or fabricate experimental parts with PBN (and PG), and need to build a simple
in-house reactor for doing so. Have 32 years experience developing vacuum equipment for ion implantation and plasma processing, so this is well within my technical skill-set, but I lack basic design configuration and processing methodology techniques.

Any information in this area would be _most highly_ appreciated.

IonSourcerer

 

[btrueblood]

You've of course seen the wikipedia link? It has a reference to what sounds like putting powdered elemental boron through a nitrogen plasma torch. see:

Robert T. Paine, Chaitanya K. Narula (1990). "Synthetic routes to boron nitride". Chem. Rev. 90: 73–91. doi:10.1021/cr00099a004.

 

[ionsourcerer]

Thank you for your suggestion. What I was looking for is a more detailed exposition/recipe of:

http://en.wikipedia.org/wiki/Chemical_vapor_deposition

I've been researching boron for over thirty years, and the more I learn- the more utterly strange it is.

Boron is completely unlike any other element in the Periodic Table, which is why it is sitting in the corner, and the common point for three distinct elemental groups. (Vertical, horizontal and diagonal)

My work is very similar to:

http://en.wikipedia.org/wiki/Crystal_structure_of_boron-rich_metal_borides

and

http://www.phys.mm.t.u-tokyo.ac.jp/research/IICS/index.htm

I am developing them as practical advanced engineering materials.

Keep an eye out for engineering with boron-based materials.

Thanks.

b.

 

[Ceramicguy]

It's a CVD process typically carried at at 1 torr vacuum or lower. Reactant gases are boron trichloride and ammonia. Deposition of stable PBN is on graphite mandrels heated to ~1800 C. A literature search of old patents by Union Carbide or Sylvania may help with some of the tricks to a good deposition. Some current manufacturers are Morgan Advanced Ceramics (New Hampshire facility), Momentive Performance Materials (Ohio facility) and Shin Etsu (Japan facility).

Bruce

http://www.accuratus.com

 

[cloa]

All those elements on that second row are odd elements. Flurine is an strange halogen e.g forms a weak acid for a combination of reasons.

 

[ionsourcerer]

The reason why I need PBN is because the boron cluster vapor EATS high purity _pressed BN_, and everything else for that matter.

Get back to me at >ionsourcerer@mac.com< and I can send you some of the strangest pictures you are ever likely to see.

b.

 

[ionsourcerer]

The reason why I need PBN is because the boron cluster vapor EATS high purity _pressed BN_, and everything else for that matter.

Get back to me at >ionsourcerer@mac.com< and I can send you some of the strangest pictures you are ever likely to see.

b.

 

[btrueblood]

It's weird stuff, for sure.

I knew some people at the former Rocket Research Co. (now part of Aerojet) that were using hydrazine arcjets to generate the plasma for various forms of CVD deposition, Silicon and Boron nitride were some of the stuff they were playing with, as well as diamond-like films. Not sure if anybody there is still working on it, but it might be worth a call. If you don't get anywhere, give me a holler back here, and I'll try some informal network methods.

 

[ionsourcerer]

Plasma is the fourth state of matter after solid, liquid, and gas. I've been designing ion sources for over thirty years, and plasma really is physics-based alchemy at its finest, hence my public internet handle is a horrible pun: ionsourcerer reflecting science and alchemy in one term.

I'm working on the quantum mechanics that make boron the weirdest element in the Periodic Table, because it appears to have absolutely no concern for the laws of physics.

As an experimentalist, I have seen more utterly _impossible_ things 'appear' to physically self-assemble according to some radically different set of laws than we are used to.

However, being an old fart, I'm convinced that no matter how bizarre, physical materials follow the established principles of Classical Physics..., at least at the traditionally accepted bulk atomic scale.

When you get down to the nanoscale and beyond, quantum effects start kicking in and eventually dominating physical matter in ways no one could have _possibly_ 'imagined' ten years ago.

The same rules still apply, but you can never be sure which ones apply, so you have to interpret them a bit differently and be willing to accept things which presently make no sense at all... except in the 'theoretical' models many of which can not be experimentally verified since the investigator and the experiment change everything just by being there.

It has taken me years to get to the point where I have learned enough about quantum mechanics to communicate in the 'language' everyone has been forced to invent out of sheer necessity.

I suppose it's like moving to a place where a language you have never heard before is spoken, and the local customs are a complete mystery, eventually you begin to start thinking in that language
and and assimilate the regional customs.

Of course boron refuses to be normal at this scale either, but it begins to appear more like the local 'normal' which is already pretty weird.

The less you 'know' about boron the better because you don't have any presuppositions to overcome.

Fun Time is over and I have to get back to work.

A nice discussion seems to be evolving.

Cheers,

b.

 

[Ceramicguy]

Have you tried the REALLY pure pressed BN grades? For example, HBC or HBT from Momentive or AX05 from Saint Gobain. As an aside, you can soak "ordinary" pressed BN in methanol to dissolve the low melting boric oxide. The material will be mechanically weaker but the yucky stuff will be removed and may improve the behavior of the BN in your application. The removal takes time, especially on thicker sections, as it is a diffusion process. It's a lot cheaper (in time and money) than trying to build a reactor and learn how to grow pyrolytic materials.



Bruce

http://www.accuratus.com

 

[ionsourcerer]

I always us he highest purity materials I can find to avoid reactive chemistry because an ion implanter is just a magnetic sector mass spectrometer on steroids and the reason for that is to avoid ppm contamination. The extraordinarily reactive free B* clusters react with _everything_ in the Periodic Tablebut PBN and PG because of their laminar crystal structure; even gold and _Xenon_ !!!

Contact me off line and I can send you peer reviewed scientific papers, and photographs to support this information. Very few research scientists even know these materials exist and those who do are still trying to explain everything to five decimal places whereas I'm working at the same academic level, but focussed on 'practical' commercialization across a vast spectrum of of industries and their applications, which I will plow back into basic and applied research, to form a closed loop system.

I'm fading fast so think I'll end here and crawl into bed for the night.

Cheers,

b.

 

[Ceramicguy]

email: bruce@accuratus.com

Looking forward to hearing from you further.

Bruce

http://www.accuratus.com