Etching titanium without Hydrofluoric acid

A. Try replacing the hydrofluoric acid with Ammonium Bifluoride

A. Try oxalic acid [affil links] as an alternative. It must be fairly concentrated, and used at an elevated temperature, but it does a very nice job of etching the surface of titanium. You will make titanium oxalate as a by-product, which should be disposed of as required.

A. We have successfully tried the hot sulfuric acid (temperature - 125 °C) with a spoon of ammonium persulphate during every cleaning /etching step to remove the titanium.

A. See letter 13456.

A. I recall an expired patent describing the use of hydrogen peroxide with ETDA, usually at about 50 °C. Etching is slow.

Ammonium fluoride or bifluoride is also slow since the dissociation constant of NH₄F is 5 orders lower than that of HF. Some ammonium fluoride based etchants use the addition of nitric acid -- that just bumps the fluoride ion concentration as well as providing an oxidizing agent and lowering the pH. One can argue the safety hazard of this mixture may be worse than using HF. The danger in HF is really the fluoride ions which are easily absorbed through the skin and forms insoluble fluorides of calcium. Care should also be used when handling ammonium fluoride.

A. For etching ti6al4v 10% HF, 5% HNO₃ and 92% H₂O with 10-20 sec immersion etching is the best way from my experience.

A. Try ammonium hydroxide, hydrogen peroxide, and water. Use volumes of 1:1:5. Maybe too vigorous if so then add additional water. Worked on removing titanium from evaporation systems.

Hello, Mohit. Since you are working with these acids on titanium, please briefly summarize what you are learning from your own experiments and try to phrase your questions in terms of the answers already provided. That way it is much more likely that someone will share their findings with you, and we'll have a clearer picture of what your issues are too. Thanks.

A. I have used Multi-Etch for titanium production. It's a non-acid (pH 6.8) alternative to hydrofluoric acid. I used it to etch titanium in my jewelry making facility.

A. Potassium hydroxide + hydrogen peroxide. I don't recall the concentrations. Room temp. Works slowly, depending on your need, perhaps several hours.

A. Anne-Lise,
Is blasting an option for you? I have found blasting to be very effective as a pre-treatment for Ti.

A. Are you talking about electropolishing or etching to reveal grain structure? There are some methods to etch without strong acids, but in room temperature it will take longer to remove required material.

A. Plasma cleaning under a mixture of hydrogen and argon plasma might be useful.

A. The use of Kroll's reagent is best for etching titanium alloys.

A. While I agree Krolls reagent is best for Titanium Etching, I have seen a couple of accidents using HF as an etchant.

For those who like to etch titanium without the dangers of handling HF, you can use a mix of Sodium fluoride and Natrium Fluoride. I am not sure what the correct amount should be.

This mix is also sold as multi-etch (in USA) and super-etch (in Europe).

A. I have used titanetch (brand name) for my titanium etching. It is similar to Multi-etch, and is sold in Europe. It doesn't use Hydrofluoric acid and is relatively safe in use. I've had great results using this product for some bolts on my bike!

  I was looking for an etchant for Titanium that didn't require HF acid. One of the posts recommended trying Oxalic acid. So I used a 50% Oxalic acid solution for 1 minute at 12 VDC and the grains came out fantastic.

A. I have successfully used Oxy-clean with very hot water and a decent amount of time. It doesn't etch as much as it oxidizes the titanium. I've done this then tumbled titanium for an aged effect.