# Where to buy alumina oxide powder



## Lolaralph (Feb 26, 2012)

I've been using alumina oxide powder and epoxy mixtures to pot my drivers in some of my drop ins, it seems to work well for heat transfer, and it's cheaper than some of the alternatives. I had been buying it from The Sandwich Shoppe, I ordered some items last week and apparently got the last package they had. I asked about them getting more, but got no response, does anyone have any idea where to buy more from, without ordering 25 pounds, as most places have a large min. order.


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## pavithra_uk (Feb 26, 2012)

http://www.sigmaaldrich.com/catalog/ProductDetail.do?D7=0&N5=SEARCH_CONCAT_PNO|BRAND_KEY&N4=319767|SIAL&N25=0&QS=ON&F=SPEC


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## Lolaralph (Feb 26, 2012)

pavithra uk,
Thanks for the link, unfortunately they are back ordered currently. Any other ideas anyone?


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## Drywolf (Feb 26, 2012)

Lolaralph said:


> pavithra uk,
> Thanks for the link, unfortunately they are back ordered currently. Any other ideas anyone?



How much do you need? I have one pound of Aluminum Oxide 220grit. I would be willing to sell half of my stock.


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## GeoBruin (Feb 26, 2012)

Were going to get pegged as terrorists on here. They'll think were making thermite. 

Try explaining that: "But seriously! It's for a flashlight!"


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## Drywolf (Feb 26, 2012)

GeoBruin said:


> Were going to get pegged as terrorists on here. They'll think were making thermite.
> 
> Try explaining that: "But seriously! It's for a flashlight!"



I use it for potting the driver as the OP does....


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## Drywolf (Feb 26, 2012)

How about this place?
http://www.ebay.com/sch/gregatweb/m...094816646&pt=US_Skin_Care&_trksid=p4340.l2562


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## Al Combs (Feb 26, 2012)

Try a Google for, "telescope making supplies".


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## Lolaralph (Feb 26, 2012)

Guys thanks for the opinions and info. Drywolf, thanks for the offer, do you find the 220 grit fine enough, the stuff I had was a fine powder. The big question, is aluminum oxide and alumina oxide the same. My sandwich shoppe order says alumina, the eBay items are aluminum, but Wikipedia states aluminum oxide is electrically isolative so I guess it's the same, any thoughts


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## Drywolf (Feb 26, 2012)

I went though the same stuff when I bought mine. They are the same. 220 worked fine for me, the Ebay stuff is finer......


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## Al Combs (Feb 26, 2012)

I looked at the 1st half of your eBay link. They all appear to be different quantities of the same 120 grit. Telescope making supplies carry grit in sizes smaller than commonly available elsewhere. The 12 micron size is a good compromise. That's roughly equivalent to 2000 grit. They sell a 5 micron grit but it's maybe a little too fine. It gets airborne too easily.


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## CKOD (Feb 26, 2012)

GeoBruin said:


> Were going to get pegged as terrorists on here. They'll think were making thermite.
> 
> Try explaining that: "But seriously! It's for a flashlight!"



actually, reacting thermite would leave iron and aluminum oxide, so it could be a handy source for alumina  

I'd look at ebay though, the selection there should be pretty good


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## Th232 (Feb 27, 2012)

Lolaralph said:


> Guys thanks for the opinions and info. Drywolf, thanks for the offer, do you find the 220 grit fine enough, the stuff I had was a fine powder. The big question, is aluminum oxide and alumina oxide the same. My sandwich shoppe order says alumina, the eBay items are aluminum, but Wikipedia states aluminum oxide is electrically isolative so I guess it's the same, any thoughts



Aluminium (or aluminum for you people in the US) oxide and alumina are the same thing, both are Al2O3. Alumina oxide doesn't make sense...


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## Essexman (Feb 28, 2012)

Could you use Zinc Oxide as an alternative?


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## Kestrel (Feb 28, 2012)

The thing about alumina / aluminum oxide is that it has a rather high thermal conductivity for an electrically-insulative ceramic. I have a significant quantity of ~400 mesh 99.9% Al2O3 powder available to me, if anybody wants some please PM me.

Me, I wouldn't bother with doing this (I don't that the effect will have much if any significance for our application), but hey, whatever looses your lumens. 

Edit: Looking at the data, Silicon Carbide is about twice as good as Al2O3, I have that available to me as well.
I may also have AlN powder which is ~ twice as good as SiC, I can check on that ...


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