Anodizing Titanium

[oregon]

Experiment: Two raw pieces of Ti anodized in different baths @ 85VDC until amperage dropped to .10. I prepared the raw Ti in a lye bath, rinsed in well water, scrubbed with dish soap in a 3M surfaced sponge and then rinsed in warm well water (handling via stainless tweezers).

One bath: TSP, baking soda and well water.
Other bath: Well water.

I rinsed off the large Ti plate in the bath between baths but only dried off the Ti rod (connects to the target) on a towel between baths.

Result: The dirty bath quickly gave the purple anodization with lots of bubbles while the clean bath gave the gold/yellowish anodization very slowly with few bubbles. Clearly, the ingredients of the bath make a different.

Before:

After:

The setup:

oregon

 

[oregon]

Battery acid (one teaspoon from an old car battery) & well water bath, same experimental parameters as above (85VDC until amps. drop to .10).

Result: Extremely quick and fluidic color change as I turned up the voltage (several revolutions of the voltage knob with this power supply) and few but tiny bubbles. Iridescent pink. (note that amps. dropped to .10 instantly, although I need a second pair of eyes because I was shocked/mesmerized by the instantaneous color change in this bath)

After:

oregon

 

[maxspeeds]

Nice job on the purple ano. I like it :twothumbs

 

[precisionworks]

anodized titanium for the most part to be a cosmetic feature

There are commercial firms that can apply thick film anodizing, primarily to reduce Ti-to-Ti fretting and galling on sliding fits or threaded fits. I've had a few phone discussions with a sales engineer at TFC, one of the larger companies that anodizes. They recommended a (not too pretty) mechanical coating called Ti Fin 400, which they state is very thick relative to the natural oxide layer always present on raw Ti - which has a range of only 50 to 250 angstroms, what I'd call nanoscopic.

As much as I'd love to try this, I can't bring myself to send the PD-S ...

http://www.titaniumfinishing.com/page09.htm

Here's an article on the soda method (which I have not tried):

http://www.popsci.com/diy/article/2005-06/titanium-technicolor

 

[McGizmo]

Barry,
When I was into anodizing Ti in making earings, I would often anodize and then take diamond burs to break through the film so that I could then apply a lower voltage and only color that which had been freshly exposed. I found from goofing around that if I zapped the metal with a high voltage (90v I would guess) that the oxide layer didn't really have a color but did have an interesting iridescence to it and this layer was a real challange to break through. Bead blasting really didn't cut it and only the diamond burrs really were effective.

I think this may have been similar to the finish you have referenced. When there were discussions here about galling of Ti, I recall thinking that one solution would be to anodize one "side" of the threaded couple with just such a film so that you would have a hard VS soft mating. Probably even better with both threads sporting the hard film?

I qualified the anodize as strictly cosmetic even considering this exception though because at the point you get the hard and thicker film, you no longer have any real color so it is not cosmetic in the sense as the colors would be considered. I believe you can also get a hard surface from some forms of heat treating. When I used to mess around welding Ti, I would get I think it is called an Alpha film or layer on the surface and man, that had to be ground with diamond for sure! Brittle as hell too! :green: I welded up a Ti windsurfing harness hook assembly that looked really cool and weighed nothing compared to the stainless ones. While board sailing between Maui and Molokai, with it on the virgin run, I heard one weld after another snap! Fortunately the way I formed it, none of these welds breaking caused a catastrophic failure. I came to accept the fact hat my welds were cosmetic and not structural.

There is no welding involved in our lights so these issues of how easily Ti can be contaminated and compromised at elevated temperatures are not considered. For the fun of it, I would like to get a Ti light heat treated sometime. The metal color and surface is really different and unique after heat treatment and the members who talk about how soft Ti is have clearly never messed with a heat treated 6-4 piece of Ti!! (Of course the naysayers would then criticize the metal as being too brittle )

 

[oregon]

I've gotten Ti, Spyderco Salt series knife pocket clips are Ti, to show color using a strong dose of household drain cleaner and a small amount of water. Is this anodization? I don't know but I was surprised by this iridescent result.

oregon

 

[Th232]

When I used to mess around welding Ti, I would get I think it is called an Alpha film or layer on the surface and man, that had to be ground with diamond for sure! Brittle as hell too! :green: I welded up a Ti windsurfing harness hook assembly that looked really cool and weighed nothing compared to the stainless ones. While board sailing between Maui and Molokai, with it on the virgin run, I heard one weld after another snap!

Ouch! What gas (if any) were you using to shield the weld? When we were laser welding some CP Ti at work, proper gas shielding made a ridiculously big difference. Never saw any difference from a visual inspection, but the results were very obvious.

 

[McGizmo]

oregon,

I would guess you are growing an oxide film thick enough to give you some light interference and hence color.

th232,

I have a TIG set up and do and did use argon. To do it right though, you almost need a chamber that is sealed and filled with argon. The other problem I likely had was one of contaminated welding rod and surfaces on the parts being welded. I believe nitrogen embrittlement (sp) is a common problem and perhaps one I experienced.

I read a story once about some forged titanium struts used either on the shuttle or perhaps a military craft that would fail. It took some serious investigation and it turned out that in the summer time in CA, the local water supply was enhanced with additional chlorine because of evaporation. The forging process used municipal water for cooling and this chlorine reacted with the heated Ti during the forging process and compromised its physicals. If I'm not mistaken, some of the early bike frames of Ti had some unexpected and uncool weld failures. I once met a guy who was a professional welder and he told me of a job he had where he would enter an inert gas filled room wearing a closed air supply suit so he would weld titanium without compromising the welds!

 

[exodus125]

this may be a dumb question, but can you use a battery charger to do this, the type you charge car batteries with?

 

[oregon]

Try it.

The color is dependent on voltage and the make-up of the bath you use.

Take a look at the color chart, measure the output voltage of the charger and see what color range you would get. You should get some results around 10 VDC +.

Please photograph your results. Thank you.

oregon

 

[precisionworks]

you almost need a chamber that is sealed and filled with argon.

For small parts, it's pretty easy to build a "glove box" where a pair of rubber gloves are sealed to openings in the side of the box ... much like a sand blast box (which can work for bigger parts). Start argon flowing into the box with a small vent allowing shop air to discharge, until an O2 meter reads 10 ppm or less & the welding can begin.

Ti isn't the worst material in the world to weld, but it is finicky. It does, however, produce beautiful weldments

 

[McGizmo]

Barry,
For a couple years, I had just such a box. I got it surplus and it was designed for bio hazards with a vacuum setup and even a double door entry box on the side. My welds were much better using it but I never depended on any of them for structural integrity. I gave the box to a friend who was a professional welder and he was engaged in doing some serious welds for a mutual friend who was going to sail around the world, single handed.

Since argon is heavier than air, you can also do a sink type weld system where you have the part and welding tip below the surface and submersed in the argon. Obviously you need still air movement for it to be counted on. I would use a burning match to confirm the presence of the argon.

 

[exodus125]

Try it.

The color is dependent on voltage and the make-up of the bath you use.

Take a look at the color chart, measure the output voltage of the charger and see what color range you would get. You should get some results around 10 VDC +.

Please photograph your results. Thank you.

oregon

this is with a 12v car battery, the color is expected at that voltage, now to find some 9v to get a blue or purple....

 

[exodus125]

what would be a good cheap, but permanent source fora power supply that would allow you to anodize in any color? like an ac to dc converter with an adjustable knob to control the current, cant seem to find one anywhere, maybe I am getting the name wrong?

 

[precisionworks]

An adjustable output battery charger (automotive type) will be the low cost option.

Just need a transformer, two diodes, one capacitor, and a volt and amp meter:

http://www.electronicsteacher.com/c...utomotive-car-and-motorcycle-schematics/7.gif

 

[oregon]

what would be a good cheap, but permanent source fora power supply that would allow you to anodize in any color?

Here you go, this is what I use, see the pic above, and I can vouch for it (no connection to the vendor): http://www.circuitspecialists.com/prod.itml/icOid/7859

oregon

 

[McGizmo]

what would be a good cheap, but permanent source fora power supply that would allow you to anodize in any color? like an ac to dc converter with an adjustable knob to control the current, cant seem to find one anywhere, maybe I am getting the name wrong?

When I wanted such a supply, my first thought was to find an old model train transformer but in talking to some folks at the local electronics supply store, they came up with a 3 amp AC variable transformer that gave you fro 0 to 100% of the AC input voltage. I think I added a bridge rectifier to convert to DC and stuck the stuff in a project box with some banana lead sockets and away I went. I should caution that at some voltage, if you aren't isolated yourself, you will pick up a buzz!

Any metal exposed to the bath needs to be titanium for good current flow through the part being anodized. I made a couple style Ti clips for holding the part and also use some ti tweezers. Thin Ti sheet metal or straps can be used for the cathode supply to the anodize bath. You can also use ti wire or welding rod.

 

[oregon]

this is with a 12v car battery, the color is expected at that voltage, now to find some 9v to get a blue or purple....

Excellent result and photo, thx.

Add another 12V battery in series for blue/purple.

Here is the color spectrum/voltage chart for reference: http://www.bme.unc.edu/~bob/titanium-spectrum-web-2.jpg

However, you can quickly, easily and cheaply create a DC power supply by connecting 9V batteries in series, output is in increments of 9 volts, with ready-made alligator connectors from Radio Shack.

Or, you could connect the 9V batteries with these:

oregon

 

[McGizmo]

Some of you have seen the pic below but I think it is a pretty clean representation of anodizing and etching a titanium piece. The pocket clip that is:

 

[ma_sha1]

Nice clip!