Titanium 6al-4v ceramic coating 2

[crazylazy]

how can i surface treat the inside of a titanium alloy (6al-4v) cylinder (dimensions 3/4" diameter, 16" length) with a ceramic coating?

 

[blacksmith37]

Anodizing may give you enough.

 

[crazylazy]

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.

 

[BMKR]

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)?

 

[crazylazy]

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.

 

[crazylazy]

i have found someone who can PVD coat my tube. thanks for the help

 

[btrueblood]

Could you share that source? I've always thought diameters below 1" and l/d more than about 2 are essentially not do-able...

 

[crazylazy]

btrueblood - yes you are right, i misread some information. anything less than 1.7" isn't really possible.

so back to square one - any suggestions?

 

[BMKR]

is CVD out of the question?

 

[BMKR]

never mind then contamination might be an issue with the 6-4

 

[TVP]

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.

 

[BMKR]

TVP,

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?

 

[btrueblood]

TVP,

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...

 

[crazylazy]

has anyone any other suggestions? the dimensions cannot be altered but i need a ceramic barrier.

 

[Maui]

You might consider this:

http://www.sciencedirect.com/science/article/pii/S0257897297000078

Maui

http://www.EngineeringMetallurgy.com