Original Date: 05/08/1995
Revision Date: 01/18/2007
Information : Ion Vapor Deposition
McDonnell Douglas Aerospace (MDA)-St. Louis has eliminated many cadmium plating and zinc coating processes and replaced them with the Ion Vapor Deposition (IVD) process. The IVD process deposits a uniform, dense coating of pure aluminum on steel, titanium, and aluminum alloy parts and provides outstanding corrosion protection. This process eliminates many of the environmental problems associated with vacuum- deposited cadmium, electroplated cadmium, and diffused nickel-cadmium. IVD aluminum is a ductile coating and will not affect the fatigue life of high-strength aluminum alloys. Figure 3-5 illustrates the basic parts of an IVD Rack Coater, including a steel vacuum chamber, pumping system, evaporation source, high voltage power supply, and internal racking system.
After the parts to be coated have been mounted onto racks and loaded into the chamber, the vacuum chamber is pumped down to approximately 10-4 Torr, backfilled with an inert gas, and a glow cleaning process commences. Following the cleaning process, commercially available pure aluminum wire is continuously fed into the chamber and evaporated. A portion of the aluminum is ionized and is attracted to the negatively charged part. This results in a dense, thick, adherent coating of aluminum.
This process has proven to be quite effective when used in direct contact with titanium where cadmium is prohibited, on steel parts that will be in direct contact with fuel, and on dissimilar metals that would normally create corrosion problems.
Figure 3-5. Ionic Vapor Deposition Rack Coater
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