Why Ceramalloying

Why is Quantum’s Calorizing superior to other forms of conventional calorizing?

Calorizing normally produces two different layers. 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. Best calorizing practice maximizes the inter-diffusion layer as the outer-growth layer is hard and brittle.

In general, at a higher processing temperature, a thicker inter-diffusion layer is created because the substrate metal is more receptive to aluminum. However, with a conventional calorizing process using pure aluminum powder, the reaction is too active and as a result an excessively thick outer-growth layer is formed. In addition, the inter-diffusion layer is also compromised as the aluminum content is too high to maintain the durability of the substrate metal. Therefore both the outer-growth and inter-diffusion layer can be damaged. To avoid this unfavourable result with pure aluminum powder, either the processing temperature or the processing time has to be reduced and this results in an insufficient inter-diffusion layer. However, Quantum’s specially formulated inter-metallic compound powder contains other elements that reduce the speed of aluminum diffusion so the resulting inter-diffusion layer has an optimum aluminum content with excellent physical properties.

Depending on the application, the outer growth layer can be beneficial because it plays an active role as an additional heat barrier. However, the unstable characteristics of the outer-growth layer may not be useful for some applications. To minimize and remove the outer-growth layer, Quantum has conducted many different trials and finally succeeded in creating a calorized layer without the outer growth layer on mild steel, ductile iron and heat resistant cast stainless steel base materials.

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