Anodizing Titanium

[bigdelicious]

Hi,

Ive searched and read a lot about anodizing titanium but I cant seem to find an answer to this question. If i anodize a piece of titanium that is threaded, will the piece no longer fit or be to tight? It seems like this would definitely be the case with HA aluminum and I think it would be for titanium because it does 'grow' a top layer on the metal. Any help is appreciated. Thank you.

 

[theslippyslug]

The threads ideally should be masked off if they are a part if the electrical path as the layer may prevent a good contact. Anodising is often used to make Ti threads smoother and prevent galling, it's so thin that is is not likely to prevent the thread engaging...

 

[jcw122]

Wow I didn't even know titanium could be anodized!

 

[precisionworks]

Type III Color Anodize typically runs .000007" up to .000025". Most thread connections have a minimum tolerance of 50X that.

Type II Gray Ano is many times thicker on titanium & is more like aluminum HAIII.

 

[darkzero]

The threads ideally should be masked off if they are a part if the electrical path as the layer may prevent a good contact. Anodising is often used to make Ti threads smoother and prevent galling, it's so thin that is is not likely to prevent the thread engaging...

Agreed. Anodizing Ti does make the threads a lot smoother in my experience. I wouldn't worry about masking off Ti threads that come in electrical contact though, for electrolyte & heat anodizing that is.

Type III Color Anodize typically runs .000007" up to .000025". Most thread connections have a minimum tolerance of 50X that.

Type II Gray Ano is many times thicker on titanium & is more like aluminum HAIII.

"Typical" Ti anodizing is much different than anodizing aluminum. Is just a very thin layer of oxidation that causes light to reflect differently which makes the eyes see the different color hues at different angles. I don't have any possible way of indicating a difference of thickness of Ti oxidation but it's much more thinner than TypeII/III anodizing on aluminum. I didn't even know you could do TypeII anodizing on Ti, guess I just never heard of it.

 

[precisionworks]

I didn't even know you could do Type II anodizing on Ti, guess I just never heard of it.

Type II (AMS2488) provides an anti-galling surface - Ti-Ti high tolerance threaded fits as well as Ti-Ti sliding fits will gall if left untreated. If even more lubricity is desired Type II is an excellent surface preparation for dry film lubricants like PTFE. If you've seen a Benchmade knife with their BK-1 coating it's similar - both the BK1 & Type II are a thick coating that retain surface oils including PTFE based products like Krytox.

Type II (AMS2488) also readily accepts solid film lubricants. Many are available & the user can spec the desired COF (coefficient of friction or µ) for predictable torque values in threaded assemblies.

 

[cummings66]

I anodize the aluminum lights I build for diving, I use Titanium clips to hold them in the acid solution so the clips will anodize during the process, they remain conductive and take on pleasing hues. The color you get is determined as I understand it by the voltage and current in use. It's quite thin from what I can tell. I can't measure it however.

 

[darkzero]

Type II (AMS2488)

Guess I misunderstood your initial post since you mentioned HAIII. The anodizing process for Al vs Ti are completely different as well as the anodized layers produced.

 

[precisionworks]

Type II Gray Ano is many times thicker on titanium & is more like aluminum HAIII.

You're right Will, different process, different layers, but both are used to produce fairly thick (measurably thick) protective coatings. Much different than Ti Type III color ano which leaves a transparent diffraction layer only a few millionths thick.