The treatment involves packing industrial components and specially formulated metal powders into a sealed container or a retort. The retort is placed in a furnace and heated to a specific temperature for a specified length of time. Chemical reactions create a transport mechanism by which aluminum is introduced into the surface of the component. This produces an inter-metallic alloy layer that provides protection against high-temperature corrosion, and erosive wear.
This pack cementation process is usually called calorizing, aluminizing, or alonizing.
There are many benefits of this technology. The introduction of aluminum into the surface of a base metal, seals the base metal. This process does not allow oxygen and other gases to diffuse into the micro-structure and cause corrosion.
Diffusion processing results in the formation of the desired alloy on the surface where it is the most needed. Through diffusion it is possible to get higher concentrations of the desired element in the resulting alloy than through direct alloying. This can increase the material’s resistance to corrosion.
Diffusion is not a line-of-sight technology. The protective layer can be created on the inside of pipes and on components with a complex shape that are difficult to protect using a coating process.
The alloy layer formed is not a coating. Due to the establishment of a metallurgical bond, the alloy layer cannot be chipped off. The protective layer can only be removed through machining.