TiN vs. TiAlN coating

[linamar]

I have an application, a cylindrical guiding rod that has a coil spring running along it and loading a device that slides on the rod.
It is a long spring, and due to the compression/detent there is high wear on the rod; the spring/rod interface is lubricated, but it operates mostly on a boundary layer lubrication.
Therefore, to minimise wear and friction I'm thinking of applying a TiN coating on the rod.
As an alternative, I would also consider a TiAlN coating, if it provides the same anti friction characteristic as the TiN (due to the neutral colour).
Now, I have no experience with these coatings, other than using cutting tools already coated by the vendor.
Which of the two option is better suited to my application?
And, what is the typical thickness of the coating?
Thanks for helping out.

 

[coatingengineer]

Hello, Linamar.
Though friction is a system-dependent parameter, AlTiN can offer lower friction (0.3) than TiN (0.4). In addition, the AlTiN can produce a hardness of 3300 Vickers, while TiN is approximately 2200. Regarding thickness, both add about 3 micrometer, per surface. Good luck.

William Gunnar

http://www.IndustrialCoatingsWorld.com

 

[linamar]

Thanks coatingengineer.

 

[linamar]

One more thing I forgot to ask: these are high temperature processes, and I may have a tempering problem at the end.
What is the usual temperature and duration of the deposition?
I may have to harden the rod since I'll lose hardess.
Thanks.

 

[TVP]

linamar,

There are a number of coatings besides TiN and TiAlN that are possible, and may be a better fit for your application if temperature and friction are the main considerations. Diamond-Like Coatings (DLC) deposited by PACVD processes have extremely low friction against steel and the deposition temperature is < 200 C. Take a look at some of the vendors of these coatings:

http://www.richterprecision.com/coating-technical-data.html

http://www.oerlikon.com/ecomaXL/index.php?site=BALZERS_EN_balinit_coatings

http://www.ionbond.com/dynasite.cfm?dsmid=84834