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RE: Beryllium Oxide

Original poster: Jan Wagner <jwagner@xxxxxxxxx>

Hi list,

On Sat, 30 Dec 2006, Tesla list wrote:
Original poster: "Breneman, Chris" <brenemanc@xxxxxxxxxxxxxx>

I think that sometimes BeO is used instead of that white ceramic insulator. From the wikipedia article on "Cavity magnetron", "Some magnetrons have ceramic insulators with a bit of beryllium oxide (beryllia) added-- these ceramics often appear somewhat pink or purple-colored (see the photos above)." One of the two photos above is a picture of a microwave oven magnetron, with a pink insulator. I actually finished taking apart a microwave oven today, and its insulator is purple-ish.

I too have taken apart a few older and some quite new ones, most did have a purple-ish insulator. Also chipped one apart once to see how the entire magnetron works, quite dusty business that was (and it was prior to knowing about beryllium, argh...)

Anyone on the list have any definitive info on whether BeO is really used in microwave ovens? Before the RoHS?

At least in the ovens I disassembled there were always just the usual yellow warning stickers about HV and about a charged capacitor, no other warnings.

Never any of those "this product contains beryllium" "highly toxic" type of stickers found on RF components or equipment that contains beryllium.

With beryllium warning stickers absent, and the ovens being consumer products for preparing food, it would seem odd if there really was any beryllium used. Or?

(Could be too good material for a lawsuit in the US where too hot coffee is sufficient to start one AFAIK ;-)

OTOH on second hand components and materials like used in coiling such warning stickers can very well be missing e.g. rubbed off and so on... :-| Would be quite cautious with machining those if they have ceramics that feel cold/metalish to the touch.

 - Jan