plating, anodizing, & finishing Q&As since 1989
Chrome plating on cylinder rod of wheel loader bubbled/blistered on dealer's lot
May 21, 2012
Q. Cylinder rod was coated with chrome plating. After assembly on the wheel loader, the machine has parked in the open air for almost one year in the dealer's lot without sale out.
Dealer found the chrome plating layer corroded. The strange thing is the plating layer did not corrode directly. The bubble on the surface emerged first and then the bubbles exploded -- the base metal is corroded.
Does any expert know why the bubble happened?
A. Hi Joey.
Chrome is more electrochemically noble than steel is, so if there is a pinhole or porosity, it is possible for corrosion to start in the substrate, and then cause a blister.
The hydraulic oil on a cylinder rod offers some temporary corrosion resistance, such that a loader which is operated every few days probably exhibits significantly better corrosion resistance than one where the oil was washed off, early on, and the rod sat exposed to sun and rain for months. You might check the operating manual and see if it has any comment about periodically operating the equipment, or protecting it from corrosion if unused for long periods. Best of luck with the problem.
Ted Mooney, P.E.
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finishing.com - Pine Beach, New Jersey