i was thinking more along the lines of PVD. but this is typically applied to the outside of a given solid. whereas i need to apply an even coating on the inside within the above dimensions.
So the 6-4 is actually a tube? I am assuming corrosion isn't your concern if you are using 6-4 Ti. What exactly is going to be flowing through the tube (something hot? hint at TBC)?
i am using 6-4 because of weight/strength properties. but i need a liner to reduce friction/cracking and with good corrosion resistance, which is why i want to line the 6-4 with a ceramic.
hot gasses and a moving metal object will be passing through.
Ceramic coatings like TiN, AlN, etc. can be deposited by PVD or CVD. Most CVD processes use high temperatures (> 250 C), but some plasma-assisted techniques are now ~ 250-280 C. CVD can coat any geometry, not just line-of-sight like PVD.
With 6-4 and Ti in general aren't you worried about hydrogen contamination? Wouldn't CVD be a higher risk for that since the majority of the deposited atoms are carried by hydrogen atoms in some form or another?
Aren't there issues of flow thru a tube with CVD, and leaving an uneven coating thickness? Maybe with a hot wire cathode running down the length it might work...
I've yet to find somebody who says they can do it with the geometry the OP stated, would love to be proven wrong...
