Issue link: http://metalfinishing.epubxp.com/i/49721
ALLOYS DEPOSITED BY CHEMICAL VAPOR DEPOSITION The Air Force Research Laboratory (AFRL) eval- uated aluminum coat- ings applied through Atmospheric Pressure Chemical Vapor Deposition (APCVD).9 Environmentally benign CVD processes using triethylaluminum as a precursor for producing high-quality aluminum coatings was explored. While promising, this process involves special high-cost, equipment. Considerable further development from a process standpoint would likely be neces- sary to implement this process for high-volume applications such as electrical connector shells. ALLOYS DEPOSITED BY MOLTEN SALT BATH PROCESSES Figure 1. Galvanic series, showing position of cadmium and viable alternative metals. (Circled area: materials providing sacrificial protection.) 1 An aluminum-man- ganese molten salt plat- ing process was explored under funding from the Environmental Security Technology Certification Program (ESTCP), but the process was plagued by inconsistent bath composition, visible fumes, and excessive crust formation [Ref. 10]. In addition, this process operated at a very high temperature, which is likely to affect the properties of aluminum shells. While this technology is promising, considerable further development from a process standpoint would be necessary to implement this process for electrical connec- tor shells. ALLOYS DEPOSITED BY IONIC LIQUID PROCESSES As an alternative to the molten salt bath process mentioned above, the use of ion- ic liquids as an electrolyte to plate aluminum is under investigation. 5,11 Ionic liq- 311