1991-10-01

Zinc Electrochemical Metallizing for Corrosion Protection of Automobile Wheel Hubs 912288

Many papers have been written for SAE on electrochemical metallizing, a modern term for “selective” or “brush” plating. These papers have dealt primarily with the aerospace industry, including the use of non-embrittling cadmium LHE® coatings for corrosion protection on aircraft. Shadowed by 30 years of successes in the aerospace industry, electrochemical metallizing corrosion protection in the automotive industry is often overlooked. Specifically, the use of selectively applied zinc coatings for corrosion protection on wheel hubs during manufacture has proven integral at several European automotive manufacturers.
In the past, environmental conditions have corroded both the hubs and wheels of automobiles. Quite often the corrosion is in the microscopic gap between the hub and the wheel, which over time causes the wheel to seize and prevents removal. This has been frustrating to both stranded motorists and shop mechanics.
The paper concludes that the use of a selectively applied sacrificial metal coating such as zinc eliminates the difficulties associated with organic coatings and greases. Because the coating will corrode sacrifically, the part will maintain a rust-free surface for extended periods of time.
By offering additional corrosion protection, electrochemically metallized zinc coatings offer quicker and easier wheel changes for motorists and shop personnel. In addition, susceptibility of car body panel corrosion can be greatly reduced. This process provides a new, practical methodology for application of sacrificial metal in automotive production. It establishes another way for the automotive engineer to improve product longevity by eliminating another of the corrosion “weak spots” in automotive design and manufacture.

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