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Are Sparks Normal in Alkaline Anodizing of Titanium?

Hi;

I am trying to make anti-wear coating on titanium's surface by anodizing it in highly alkaline solution.

I have prepared a solution which has got pH > 14. After passing 130V there are sparks occurring at the surface of the titanium. Sparks are very little and forming at all over the surface. when I get to 200V spark amount is increasing and I hear a buzz sound.

are those sparks are normal? for a proper coating what is the suitable voltage.

thank you very much.

Jason Talasci
student - Karlsruhe, Germany
2007

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I have not come across alkaline anodising of titanium.
My thoughts are that making titanium anodic in an alkaline solution would be a very good way of dissolving the titanium to produce (sodium/potassium) titanate.
At 200 volts, I am not surprised to see sparks! I would look very carefully at the safety of this.
I suggest that you use 10-20% sulfuric acid and consider 50 volts absolute maximum

Geoff Smith
Hampshire, England
2007

I have tried acidic solutions. I think, they don't provide any wear resistance. they are just colouring the titanium by thickening the surface oxide layer.

Jason Talasci
- Karlsruhe, Germany
2007

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You are correct, Jason. You may see AMS 2488D as a starting point.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

adv.