Coating/bonding metal on alumina

Hi,

I am a grad student looking for a different methods to join alumina tubes to metal tubes. Currently, use metal compression fittings to make a high pressure, high temp seal on a heavy-wall alumina tube (3/8"OD) closed-ended tube and have it connect up to metal fittings (using something similar to a swagelok system). Have success most of the time.

I am looking to "bond" metal ferrule/sleeve to the ceramic tube by bonding metal to ceramic and then brazing metal sleeve to the metal coated on the ceramic.

Just how strong are the metal-to-ceramic bonds?

Is there a metal-to-metal connection technique that won't weaken the ceramic-to-metal bond?

Typically, how thick is the metal coating?

Can the coating area be controlled (I only need the outer area coated (L~2 cm), but don't want the inside of the tube coated)?

Can anyone recommend some companies for low quantities?

Any other ideas/techniques?

In the archives, I found references to electroless processes (601). I would really love to be able to search the entire archives at once-either have one big file with all the letters that I can download or have a search engine. It was a pain to search each Q's file.

Thanks for your help, Michael

Ed. note: July 2000. Hopefully our recently upgraded search engine , now referenced near the top of this page, meets your needs.