BeO

Nixie · 12th August 2006, 04:26 AM

I got some thermoconductive ceramic spacers from eBay, but I don't know the type of ceramic. How do I make sure they are not beryllium oxide, which is highly toxic and often used in such applications?

infinia · 12th August 2006, 05:25 AM

Hi
I have a very fuzzy memory about the color but they seem to look very darkish metallic or something similar to anodized aluminum. All the ceramics are white(ish). I would not worry about it unless you are going to machine them and then snort the dust. Much more things to worry about.

Nixie · 24th August 2006, 12:29 AM

The ones I have are purplish, but probably dyed.

anatech · 24th August 2006, 01:08 AM

Hi Nixie,
Look here for some hints. http://www.watlow.com/literature/pro...0insulators%22 Do not try the melting point test.

High voltage stuff again eh?

-Chris

john curl · 24th August 2006, 01:12 AM

Don't mess with them. If you are concerned, use something else, but
DON'T mess with heating, scratching, etc. White is also normal for BeO.

anatech · 24th August 2006, 01:22 AM

Yes, white or off-white.

Hi John,
I think Nixie is looking for the very high voltage breakdown rating on these. He is hoping they are BeO types.

Everyone else, get rid of them at a hazardous disposal facility. This you don't need.

-Chris

john curl · 24th August 2006, 01:25 AM

I just looked at my selection of BeO and Al TO-3 spacers. The AL spacers have AL stamped on them! BeO? No ID. IF the spacers are unknown in composition and say NOTHING on them, presume they are BeO! Go figure, you would think that they would be marked, BUT they are not.

Nixie · 24th August 2006, 04:05 AM

Quote:

Originally posted by anatech
Do not try the melting point test.

Well, I can reach that temperature, but the thing is I don't have a way to measure it.

There is no label on them, and I think they're Russian military old stock (I got them from kwtubes on eBay).

They seem a bit more powdery than the alumina and magnesia ceramic crucibles I have.

According to the article, only inhalation of the dust is a hazard. "Handling of solid shapes presents no dermatitis or skin absorption problem." I figure as long as I don't try to machine them without a mask, and avoid applying friction to them, it should be safe.

As for my high-temperature/high-voltage stuff, I'm not using ceramics but sapphire, which has a higher melting point and is much stronger (though machining it is difficult even with diamond bits under water).

anatech · 24th August 2006, 01:57 PM

Hi Nixie,
Not that you should do this, but you can rough guage the temperature by what colour a known substance glows at. Another thought, can you test the breakdown voltage reliably? That might be safer.

Hi John,

Quote:

The AL spacers have AL stamped on them! BeO? No ID.

What where they thinking? I thought they were supposed to be marked. I had some that were. I got rid of them as I never have a need for anything over mica.

-Chris

jneutron · 24th August 2006, 02:17 PM

Marking is not required on either alumina or beryllia.

Product using BeO needs an identifier.

It's perfectly safe to have and use BeO..as stated, inhalation is the only hazard. It is not toxic orally, nor topically.

Go to the Brush Wellman site, they provide a good explanation..

BTW, roughly 4% of the human population is susceptible to berylliosis. As of ten years ago, from what I recall, there was no test capable of determining susceptibility, therefore all are considered susceptible.

If I were in your position, I'd do a thermal test. BeO has themal conductivity of aluminum, alumina is 1/5th that. Mount a device, push power, alumina should be about 3 times the thermal drop.

material thermal conductivity, W /inch C

Cu 10.2

aluminum 5.3

BeO 6.3 note: actually it is (340-T)/61.7

Alumina (99%) .94

Cheers, John

12th August 2006, 04:26 AM	#1
Nixie Banned Join Date: Jan 2006 Location: Vancouver, BC	BeO I got some thermoconductive ceramic spacers from eBay, but I don't know the type of ceramic. How do I make sure they are not beryllium oxide, which is highly toxic and often used in such applications?

12th August 2006, 05:25 AM	#2
infinia diyAudio Member Join Date: May 2005 Location: Californication	Hi I have a very fuzzy memory about the color but they seem to look very darkish metallic or something similar to anodized aluminum. All the ceramics are white(ish). I would not worry about it unless you are going to machine them and then snort the dust. Much more things to worry about. __________________ like four million tons of hydrogen exploding on the sun like the whisper of the termites building castles in the dust

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24th August 2006, 12:29 AM	#3
Nixie Banned Join Date: Jan 2006 Location: Vancouver, BC	The ones I have are purplish, but probably dyed.

24th August 2006, 01:08 AM	#4
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Nixie, Look here for some hints. http://www.watlow.com/literature/pro...0insulators%22 Do not try the melting point test. High voltage stuff again eh? -Chris

24th August 2006, 01:12 AM	#5
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	Don't mess with them. If you are concerned, use something else, but DON'T mess with heating, scratching, etc. White is also normal for BeO.

24th August 2006, 01:22 AM	#6
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Yes, white or off-white. Hi John, I think Nixie is looking for the very high voltage breakdown rating on these. He is hoping they are BeO types. Everyone else, get rid of them at a hazardous disposal facility. This you don't need. -Chris

24th August 2006, 01:25 AM	#7
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	I just looked at my selection of BeO and Al TO-3 spacers. The AL spacers have AL stamped on them! BeO? No ID. IF the spacers are unknown in composition and say NOTHING on them, presume they are BeO! Go figure, you would think that they would be marked, BUT they are not.

24th August 2006, 02:17 PM	#10
jneutron diyAudio Member Join Date: Jan 2004 Location: away	Marking is not required on either alumina or beryllia. Product using BeO needs an identifier. It's perfectly safe to have and use BeO..as stated, inhalation is the only hazard. It is not toxic orally, nor topically. Go to the Brush Wellman site, they provide a good explanation.. BTW, roughly 4% of the human population is susceptible to berylliosis. As of ten years ago, from what I recall, there was no test capable of determining susceptibility, therefore all are considered susceptible. If I were in your position, I'd do a thermal test. BeO has themal conductivity of aluminum, alumina is 1/5th that. Mount a device, push power, alumina should be about 3 times the thermal drop. material thermal conductivity, W /inch C Cu 10.2 aluminum 5.3 BeO 6.3 note: actually it is (340-T)/61.7 Alumina (99%) .94 Cheers, John

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