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Titanium -Ceramic Joint

Titanium -Ceramic Joint

Titanium -Ceramic Joint

(OP)
How Titanium -Alumina ceramic joints(by diffusion bonding process) are made. We do not want to use adhesives.Is there any site or any practical data available for this. What should be the temperature, pressure and intermediate material required for this making this joint.

"Knowledge is power"

RE: Titanium -Ceramic Joint

Brazing?

RE: Titanium -Ceramic Joint

(OP)
No it is not brazing. I am talking about diffusion bonding. This kind of joint is particularly useful for making Ultra High Vacuum components. Brazed joints can not be used for UHV applications.

"Knowledge is power"

RE: Titanium -Ceramic Joint

arun17,
Why do you say "Brazed joints can not be used for UHV applications."  Is not (1cc Helium/yr) leak rate at 0.00000001 mmHg partial pressure considered UHV?  I have written processing for and tested brazed joints that fulfill this requirement.

Jesus is THE life,
Leonard

RE: Titanium -Ceramic Joint

Brazed joints work in satellites just fine

RE: Titanium -Ceramic Joint

You braze titanium to alumina by placing any Ag-Cu braze alloy in between and heating in argon or vacuum to approx. 900C.

RE: Titanium -Ceramic Joint

Brazing is a very economical process. You can find good detailed references and some process parameters in the following paper:
 R.M. do Nascimento, A.E. Martinelli, A.J.A. Buschinelli, Review Article: Recent advances in metal-ceramic brazing, Source: Ceramica vol.49,(2003) 178-198. I would like to take your attention on the pages 187-190: Metallization of ceramics, where Al2O3 was metallized mechanically by Ti in order to produce a Ti film to increase a wettability of the ceramic surfaces.

If you choose brazing, take into consideration the thermal expansion coefficient mismatch between metal and ceramic, the stresses occuring during cooling in the joint interface, melting and operating temperature of the brazing filler metal. Most likely you need a furnace with inert atmosphere to avoid oxidation, depending on the size of the parts you need to join.

If you choose diffusions bonding, how effect the required higher process temperatur and pressure the quality of the joint. Which equipments you need to make the bond. Lots of questions are to be answered , to be able to make the right decision.
If you would like to read more: Check out The World Centre for Materials Joining Technology

/Ceramics - materials, joining and applications Link:  
http://www.twi.co.uk/j32k/protected/band_3/jk54.ht...

/Diffusion bonding - Ceramics and ceramic/metal joints Link:
http://www.twi.co.uk/j32k/protected/band_3/ksjaf00...

Good luck, hope its no too late and help you  further: Leonora

RE: Titanium -Ceramic Joint

(OP)
What kind of strengths could be achieved with brazed joints?

"Knowledge is power"

RE: Titanium -Ceramic Joint

Hi Arun17,
My research interest is different, not alumina, but ceramic/metal brazed joint, anyway in the literature you can find there are other material couples and technology parameters achieving different results.
My question is, which mechanical teting methode are you interested: tensile test, simmetrical or assimetrical 4 point bend test, shear test e.t.c.? What are your requirements for the joints?

Again there were reported results by Members of the Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tenn as follow:
J.P. Hammond, S.A. David, and M.L. Santella : Brazing Ceramic Oxides to Metals at Low Temperatures, Welding Research Supplement (1988) pp. 227-232, have been publishing results of joints Al2O3/TiC-Ni interface at room temperature shear strength of 233MPa, Al2O3/Nb-1Zr interface at room temperature shear strength of  125 MPa, Al2O3/Ti interface at room temperature shear strength of 78MPa

Can you access some database e.g. Cambridge Scientific Abstract, Weldasearch, Materials Research Database or Metadex, Ceramic Absracts, AWS, or Edison Welding Institute?

Do Nascimento, R.M.; Martinelli, A.E.; De Almeida Buschinelli, A.J.; Lugscheider, E.; Sigismund, E.: Microstructural evolution and mechanical strength of metal alloys brazed to alumina mechanically metallised with titanium,
Source journal: Welding and Cutting (2004) no.2, pp. 96-102
Published by German Welding Society: DVS Verlag Düsseldorf
http://www.welding-and-cutting.info/
Contact person: Carolin Hesse

I wish you good luck: Leonora

RE: Titanium -Ceramic Joint

arun17,

The joint will be stronger than the Alumina substrate.  Typical high purity Alumina has a tensile strength of about 9,000 psi.  Compressive strength of abouot 300,000 psi.

Sorry -- this post likely a wee bit late to do you much good.

RE: Titanium -Ceramic Joint

You can braze titanium to alumina by surface treating one or both materials then brazing with Ag, Cu, ZN alloy at 700C using a flux in atmosphere with induction torch, etc.   

The right alloy will also relieve the stresses from the differences in expansion of the materials.

Bond strength will be considerably in excess of the rupture strength of the materials.  

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