Evaluation of aluminum-manganese as a cadmium replacement

The Department of Defense (DoD) is reducing, and will eventually eliminate its current reliance on cadmium-based coatings for defense systems due to the environmental and health hazards posed by cadmium, a toxic metal and a human carcinogen. Compliance with environmental, safety and health regulations is becoming prohibitively expensive due to cadmium's toxicity. In addition, the potential for limited operations overseas exists due to foreign restrictions regarding cadmium containing parts. As a result, non-toxic substances must be found to replace cadmium coatings. Aluminum-manganese may provide the functional performance of cadmium without its detrimental toxic properties. This effort will demonstrate the efficacy of electroplated aluminum-manganese coatings in replacing cadmium coatings. Using a molten salt bath, aluminum-manganese can be easily and inexpensively plated onto components, including internal diameters, complex geometries, and threaded applications. The salt bath is operated at 190 degrees C and is composed of aluminum chloride, sodium chloride, potassium chloride, and a small amount of manganese chloride. The goal of this effort is the implementation of a production scale molten salt electroplating system at Naval Aviation Depot (NADEP) North Wand in San Diego, California. Aluminum-manganese coatings are targeted for use in applications in which other coating technologies have been unsuccessful in replacing cadmium. The replacement of toxic cadmium coatings with non-toxic aluminum-manganese coatings will save DoD environmental compliance costs, and will provide protection to human health and the environment.