Aluminum Corrosion Resistance and How to Get Consistent Results from Neutral Salt Spray Testing

corrosion resistance

Plated aluminum is notorious for its susceptibility to corrosion. When it undergoes NSS testing, aluminum plated with electroless nickel often falls short of the 100-hour MIL-SPEC standard. That’s why it’s so important that you use a high-quality electroless nickel plating bath. Here’s a look at why corrosion resistance with aluminum is difficult and how you can increase your chances of success.

HOW do finishers use neutral salt spray (NSS) testing?

Neutral salt spray (NSS) testing is a quality-assurance test for metal parts finished with a surface coating. It’s used to check the corrosion resistance of a particular finish. Surface finishers use NSS testing to evaluate the corrosion resistance of their electroplated, galvanized, and painted finishes. Typically, testing subjects parts to 96 or 120 hours of salt spray before checking how well finishes hold up to the corrosive effects of salt and water.

WHY is aluminum so difficult to plate to MIL-SPEC standards?

Achieving consistent corrosion resistance results with aluminum is notoriously difficult. Aluminum must pass a 100-hour NSS test to meet MIL-SPEC standards, which is a very high bar. Without a robust electroless nickel bath, the salt spray used in NSS testing pits and corrodes aluminum after just 36 hours of exposure.

WHAT should I look for in an electroless nickel bath for aluminum?

Look for an electroless nickel bath that is pH self-regulating and offers unique stabilizer/complexor chemistry, so the finish protects the aluminum within the salt bath. Compliance with RoHS, WEEE, and ELV standards is a plus, too.

The electroless nickel bath Seacole recommends

We recommend Metal Chem’s Meta-Plate UCB to meet corrosion resistance specifications over aluminum. No other electroless nickel bath comes close to consistently meeting the 100-hour MIL-SPEC standard for aluminum.

Meta-Plate UCB easily attains the 100-hour standard and can be used in your monthly NSS testing. It has excellent copper initiation and contains no lead or cadmium. Meta-Plate UCB consistently produces pit-free surfaces. It’s also compliant with ELV automotive, RoHS and WEEE electronics, and Green Initiative standards.

If you’re looking for an electroless nickel plating finisher that delivers consistent corrosion resistance, Seacole can help. Contact our team of experts to find the chemistries that are ideal for your process.


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