High Temperature Oxidation of Slurry Aluminized Deformable Austempered Ductile Iron (DADI)

Abstract

This work reports on the aluminization and oxidation behaviour of a new class of cast iron (Deformable Austempered Ductile Iron, DADI). The slurry aluminization resulted in uneven coatings due to the lack of wettability of molten aluminium to the graphite inclusions of the substrate. In spite of this, the isothermal tests at 650°C for 100h in air revealed a drastic reduction of oxygen uptake related to the formation of mixed Al-containing spinels compared to the very unprotective iron oxides formed in the absence of coating. It derives that deposition of thicker aluminide layers by precoating with e.g. nickel would be a promising way to protect further DADI cast iron.