High Vacuum Silicon Removal from Titanium

Q. I have two questions. 1) How does Titanium react with Alconox powder? And 2) How does Liquinox clean Silicon Oils? If possible, I would like to have one type of cleaning solution. If not possible, then we will use what is necessary. We clean 304 STL, OFHC Copper, Alumina Ceramic, & Titanium.

I was planning to use Alconox for the 304 Stl, Copper, & Ceramic. They can be contaminated with Silicon oil. The Titanium is a new material added to our mix for medical device cleaning. Not sure if it will be contaminated with silicon oil but still needs to be cleaned for ultra high vacuum service like the rest of our parts.

A. Thanks for the additional information.  Silicon removal is tough.  To remove silicon oils from parts clean in very hot (over 77 deg C) 2-3% (20 g/L) Alconox® detergent for 20 minutes followed by a very hot (over 77 deg C) rinse.

Alconox® Powdered Precision Cleaner is better at silicon oils than Liquinox® Critical Cleaning Liquid Detergent. The high temperature is critical to be above the softening point of the silicon oil which improves the rate of emulsifying. The very hot rinse is required to avoid breaking the emulsion and redepositing the silicon oil. For ultra high vacuum service, and extremely thorough rinse is required. A typical rinse might be to rinse two times in water followed by a final high purity water rinse.

An ultra high vacuum rinse would require immersing in 6 separate tanks of high purity water. The first tank must be over 77 deg C. After the first tank, it is acceptable to use ambient temperature rinses. If you clean the copper at the same time as the stainless steel or titanium, you run the risk of galvanic reactions that may form deposits on the copper. Ideally clean the copper parts separately.

Copper in very hot Alconox might darken depending on contact time. Possibly you can clean short enough to avoid to avoid darkening. If the copper is darkening excessively in Alconox, then I would recommend that you use a 4% Citranox solution at above 77 deg C with the same thorough very hot rinse. Citranox is not quite as good on silicon oils, but it has far less risk of attack on copper. Titanium will not be attacked by Alconox powder. If you are already using the Alconox for the other parts because of the silicon, certainly you can use it for the titanium.

In short high temperatures are your best bet for silicon oils, with an initial hot rinse.  Acidic detergents will be safer on more reactive metals like copper and aluminum.   For further information please do not hesitate to contact us.

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