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Deionized water and aluminum

2001

We are an aerospace company that deals with aluminum forgings and castings. Our problem is that we have deionized water that is staining our aluminum castings both in the clean tank area and EDM drilling unit. This has been an on-going problem for almost one year.

Does anyone know the acceptable high and low measurements for both the conductivity and PH of DI water when used with aluminum? We have the measurement equipment but I need the allowable limits.

Thanks in advance.

John Berenyi
- Ogden, Utah, USA

Could this be bi-metal corrosion? If it is the staining is caused because the coolant is too lean. I believe the pH to be 7.6 or 8. And the chloride to be 200 ppm.

Irene Bryant
- Valencia, California USA
2003