Lubricant Testing 101: Copper Corrosion by Nye Lubricants

Lubricant Testing 101: Copper Corrosion by Nye Lubricants


Nye Lubricants performs a variety of tests
in house on our lubricants. A full complement of laboratory equipment
enables us to complete qualification testing to ensure the design and
performance requirements of your application are met. This video will feature copper corrosion
testing, also known as ASTM method D-4048. A copper corrosion test is
performed to ensure that a grease will protect the metal surfaces it comes in
contact with overtime. This test is often performed for automotive companies to
determine how suitable a lubricant is for lubricating parts such as bearings that
contain copper or copper alloys because corrosion can cause premature bearing
failures. The test begins with the technician
polishing a copper strips sample. The copper strip is then completely immersed
into a tightly packed sample of grease which is heated in an oven or liquid
bath at a specified temperature for a defined period of time. Commonly used test conditions are 100 degrees Celsius, plus or minus 1 degree Celsius, for 24 hours,
plus or minus five minutes. Both the time and temperature conditions can be
adjusted according to your product application. At the end of this heating period the technician will remove the copper strip from the grease, wiping off the
excess grease, and then washing the copper coupon with acetone. The copper strip is then visually
compared to the ASTM copper strip corrosion standards. This test is
subjective as the results are determined by the eyes of the individual technician
performing the test. Nye lab technicians are highly skilled in this test and they
have conducted countless copper corrosion tests. The technician reports
the results as a number followed by a letter according to the ASTM ranges. These
ranges include: freshly polished, slightly tarnished (1a to 1b), moderately tarnished
(2a to 2e), dark tarnish (3a to 3b) and corrosion (4a to 4c). This test does not
measure the ability of the grease to inhibit copper corrosion caused by
factors other than the grease itself, nor does it measure the stability of the
grease in the presence of copper. However, it does ensure that a grease
will protect metal surface it comes in contact with over time. If you have any
further questions regarding Nye’s testing capabilities please visit our website at
Nye Lubricants dot com, or call us at 1-508-996-6721 Nye Lubricants, Technology in Motion

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