This specification covers the requirements for aluminum diffusion of metals applied by pack cementation process. The three classes of aluminum diffusion coating, defined by the type of base metal, are as follows: Class I (carbon and low alloy steels); Class II (stainless steels); and Class III (nickel-based alloys). Specimens shall adhere to processing requirements such as substrate preparation, high and low activity pack mix, materials (masteralloys, activators, and inert fillers), loading, furnace cycle, post cleaning, diffusion heat treatment, post straightening, visual inspection, and marking and packaging. Specimens shall also adhere to coating requirements such as diffusion thickness, aluminum content, appearance, and mechanical properties (tensile strength, and macro- and micro-hardness).

1.1 This specification covers the requirements for aluminum diffusion of metals by the pack cementation method. Pack diffusion employs the chemical vapor deposition of a metal which is subsequently diffused into the surface of a substrate at high temperature. The material to be coated (substrate) is immersed or suspended in a powder containing aluminum (source), a halide salt (activator), and an inert diluent such as alumina (filler). When the mixture is heated, the activator reacts to produce an atmosphere of aluminum halides which transfers aluminum to the substrate for subsequent diffusion. The aluminum-rich surface enhances corrosion, thermal stability, and wear-resistant properties.

1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.