Why is Quantum’s Calorizing Superior to the other form of conventional calorizing?
Calorizing normally produces two different layers. The one layer is an inter-diffused layer that is the inter-metallic compound of aluminum and the substrate metal.
The other layer is an outer-growth layer, which is mostly iron aluminide and aluminum oxide at the surface.
Good practice of the calorizing process maximizes the inter-diffusion layer portion because the outer-grown layer is hard and brittle.
In general, at a higher processing temperature, a thicker inter-diffusion layer can be obtained because the substrate metal will be more receptive to aluminum.
In the process of conventional calorizing with a pure aluminum powder, the reaction inside of the retort is so active that it ends up with a huge outer-growth layer and the aluminum content in the inter-diffusion layer is too high to maintain the durability of the substrate metal. This means that not only the outer-growth layer but also the inter-diffusion layer can be damaged. To avoid this unfavorable result, the processing temperature with pure aluminum powder has to be lowered or the processing time shortened and this results in an insufficient inter-diffusion layer. Quantum’s inter-metallic compound powder contains other elements that reduce the speed of aluminum diffusion so that it will create an excellent and significant inter-diffusion layer with an optimum aluminum content.
Depending on the application, the presence of the outer-growth layer can be beneficial because it plays an active role as an additional heat barrier. However, the instability of the characteristics of this outer-growth layer may not be useful for some applications. To remove and minimize the outer-growth layer, Quantum has conducted many different trials and finally has succeeded in creating a calorized layer without the outer-growth layer on mild steel, ductile iron and cast heat resistant stainless steel base materials.