"Baron" wrote in message
...

Both Aluminum oxide and Beryllium oxide are extremely hard materials.
I
belive that the pink dye was used later to specifically identify
Beryllium. So its a good chance that the white insulators that you
have are Aluminum oxide. Even so its not a good idea to try to grind
them.

Beryllia is white, the same as alumina. There is no standard on coloring
beryllia insulators for use as heat transfer links. No dye is used as
the beryllia is sintered (fired) at very high temperatures. Instead a
colored inorganic metal oxide is added in small amounts. Beryllia has
about seven to ten times the thermal conductivity of alumina, so if the
links were used with high power parts, they are probably beryllia.
Beryllia has about one third better thermal conductivity than aluminum
nitride in the 25 to 300 C temperature range. Only diamond and cubic
boron nitride are better thermal conductors (but at an exceptionally high
cost).

Until you know for sure what these insulators are made of, treat them as
beryllia. I.e., do not grind or crush them.

73, Dr. Barry L. Ornitz WA4VZQ