You can epoxy, use active braze alloys or, sometimes, use standard braze alloys.

Tom

Actually I would like to receive the most monolytic alumina possible.

Is there a way?

Yes, it is possible to braze ceramics together with more ceramics.  Typically called "fusing".  Tends to work better (i.e. achieve closer to monolithic stress capabilities), if done on higher purity aluminas.  It can be done on fired ceramics, or on green.

What kind of material do I have to use? Where can I obtain the fusing material?

Alumina purities above 92%

Thanks in advance

I would guess that there are glass frits available for joining the aluminas/aslumina.

If you can tolerate a thin interface of a few thousandts of an inch of metal, the Moly-Manganese metalllizing process will give you as much as 9,000 psi tensile strength.  I can give most of the processing details if you are intereted.

Jesus is THE life,
Leonard

Who delivers those glass frits?

I think that is the way to get a monolytic alumina, but I'm searching for information about it.

JvdWal,

I did a word search for glass frits on this forum and came up witht this thread so I did a Google search and seletcted a few links that might lead you to something:

http://www.cyberexports.com/prodbuysell.asp?Opt=B&pname=Glass+frits+a+d%20powders&QS=(Buyers.PRCODEN+LIKE+'320740*')

http://www.glasschange.com/equip/equip_115.html

http://www.urbansky.com/usingnorthstarfrit.htm

Jesus is THE life,
Leonard

Can you describe the parts and the operating conditions (stresses, temperature, etc.)?

Yes, brazing is very doable.

Temperature goes from 20 til 300 degrees.
the joined Alumina parts have to be gas tight.

The mean point is to get monolytic material.

You can try an active metal paste from Wesgo or Lucas Milhaupt. It will be a silver-based braze with titanium added (a few percent). You paint it on the mating faces. dry them, put them together in an graphite alignment fixture and heat the assembly in vacuum or argon to 900-950C. When the parts cool down, take them out. Your parts are brazed together.

JvdWal,
1)  By monolithic, I assumed you wanted the same material throughout (Alumina in this case).  But if you simply mean one contiguous piece then JimMetalsCeramics suggstion might simplest if it provides the properties you need.

2)  The Mo-Mn process mentioned in my June 27 post, will give you leak tightness of 1 x 10^-8 cc/year leak rate of Helium.  Also note the high tensile strength attained with the Mo-Mn process.

Jesus is THE life,
Leonard

Thank you for your replies, Jimmetalsceramics and metman.

As said in your first point metman, I want the same material throughout for a semiconductor application. Metal may not be used in this application. What is possible

For an other application where leak tightness is important, sounds the Mo-Mn process interesting. I can tolerate a thin interface of a few thousandts of an inch of metal. Refering to your post June 27, wat are most of the processing details?

Mo-Mn is not necessary. You have two reasonable options;

-active metal brazing or,
-joining with a glass layer.

In either case, you apply a powder-filled ink to the joint and heat the parts together.

We brazed alot of Alumina to TZM

35/65 Copper Alloy in a Vacuum furnace

Wesgo is the company that sells brazing
alloy out of California. They also have a rep
in Milwaukee, Wisconsin.

If you need more info you can call me
at 312.777.4943

Andy