Evaluation of Alternatives to Electrodeposited Cadmium for Threaded Fasteners Applications (III)
Since 2005, Alcoa Fastening Systems (AFS) and Lockheed Martin have been partnering to identify a Cadmium (Cd) plating replacement for threaded fasteners. Previously reported Phase I, II and III studies resulted in alternative coatings that indicated promise as suitable plating materials. Phase IV and V studies continued the program by testing two different fasteners (NAS1580 and NAS4452) manufactured in AFS facilities. Testing included plating material characterization such as coating thickness, torque-tension relationships, locking and breakaway torque measurements, salt spray (fog) corrosion, stress corrosion, and push-in and interference properties. Additionally, mechanical properties of the plated fasteners were tested (tensile, double shear, durability, and fatigue). Candidates included two electroplated zinc-nickel coating systems (Zn-Ni and Zn-Ni2) and an electrodeposited aluminum coating (AI).