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Aluminum stays sulfur-contaminated despite ultrasonic cleaning and HNO3

2003

First step, we used ultrasonic to clean aluminum 6061-T6 coupon ,then we dipped it into HNO3 :Water (1:1) for 1 minute. Last we rinse it in hot D.I. water for 1 minute. But our customer analyzed its surface and it found sulfur that contained higher. We suspected that one of the reasons was machining lubricant. Should we use other chemical solutions to clean it or need to increase cleaning process to reduce sulfur?

Thanks!

Tony Chen
Machine Shop - Kaohsiung, Taiwan

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You may try to remove the machining fluid with immersion in Kerosene. Then add 1 to 2% (81%) Phosphoric acid to the ultrasonic unit for 2 to 5 mins.at 35 °C, Rinse in clean water and dry at 100 deg.C until dry.

Brian J Green
engineering - Geelong, Australia
2003

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Ed. note: Kerosene is dangerously flammable. It is rarely an appropriate cleaner, and only when people realize exactly what they are dealing with.