Radiator caps with magnesium anodes were supplied by Rad Cap Products. for testing. Two different testing methods were used to evaluate the magnesium anode. The two techniques were electrochemistry and immersion testing.

 

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Electrochemistry

 Electrochemistry was performed on the magnesium anode supplied from Rad Cap Products. Two electrochemical techniques were used to evaluate the magnesium anode. The two techniques were galvanic corrosion and Ecorr vs Time. The test fluid used for electrochemistry test was proposed ASTM synthetic used coolant at 50% coolant at 180 F.

Galvanic corrosion was performed against the magnesium anode and the six metal specimens used for the ASTM D-1384. These six metal specimens are copper, solder, brass, steel, cast iron and cast aluminum. Six galvanic corrosions were performed and all six galvanic corrosions produced the same current of +20.8 uA.

The table below represents the data obtained from the Ecorr vs Time scans on the various metal specimens.

 

 

 

Immersion Testing

The other test method used to evaluate the magnesium anode was immersion testing. ASTM D-1384 Corrosion in Glassware was the method followed for immersion testing. The test fluid used for testing is the proposed ASTM synthetic used coolant. The testing was performed with the standard ASTM Test bundle and with the standard ASTM test bundle with the magnesium anode. The magnesium anode was placed at the front of the test bundle in front of the copper coupon separated by a brass spacer. The table below contains the weight losses for the coupons.

 

ASTM D 1384 TEST RESULTS

 

Note: * Maximum corrosion weight loss as specified in ASTM D 3306-94 specification for EG base engine coolants.

* Indicates Corrosion level at or above maximum corrosion rate specified in ASTM D 3306-94.

 

The set of coupons without the magnesium anode corroded much worse than the set of specimens with the magnesium anode. The magnesium anode does provide better protection to a cooling system with marginal coolant.

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Important note:  The above testing was performed in warm engine coolant, much like the conditions of your vehicle. It is a very very specific test to replicate real under hood conditions. Most of the other references to The Galvanic Series are measurements taken in seawater, since electrolysis and galvanic activity is a huge issue with ocean craft. While there is much galvanic test data that can be useful, the warm coolant testing above was done for the specific purpose of fighting automotive electrolysis. Specific, targeted testing. That's what we want, right?

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