Sublimation temperature & pressure of metals

[Newbies_Kid]

I have a piece of Alumina (Al203) to be coated with metallic multilayer of Cu-Al-Ti. I choose to use evaporation method instead of Plasma sputtering because some books says Plasma sputtering PVD cause some impurities incorporated in thin coating.. So my problem is to find the phase transition diagram of those metals because i need to know the pressure and the temperature at which the solid metals start to vaporize.. Just their critical point (P-T diagram) would also be helpful.. Thanks ...

[CaptainPanic]

The weird thing is that solids already have a vapor pressure. In the case of metals, that's just incredibly low (so low that we can't measure it).

The question you must be asking is what vapor pressure you want to have, and at what temperature this is reached.

 

I googled for [vapor pressure titanium], and I got a hit. however, it was not for free, so I can't give you the answer. The information is out there.

 

I have experienced that very often a data set for vapor/liquid equilibria are described in a different paper than liquid/solid... and again in a different publication than vapor/solid.

So, to search for the entire phase diagram is maybe too ambitious. Try instead to search for the individual equilibrium lines, and construct the diagram yourself.

 

Good luck!

[John Cuthber]

Well, because there's a gadget called the "Titanium sublimation pump" the data fro titanium is sort of available

Have a look here

http://cas.web.cern.ch/cas/Baden/PDF/Vacuum.pdf

It says they run the pumps at about 1300C.

 

I also have a charming old book called "Handbook of electron tube and vacuum techniques"

It lists the temperatures for evaporating a bunch of metals (i.e. where the pressure reaches 10µ of mercury)

Al 996C

Cu 1273C

and Ti 1546C

Apart from the Ti, those temperatures are above the melting points of the metals which means you will be boiling them, rather than subliming them. I don't know if that will matter.