Density determination for oxide scale formed on steel plate considering non-stoichiometry of Fe_1-xO

Density of oxide scale formed on steel is essential to derive thermal conductivity, which is used for the process simulation for cooling of steel plate in hot-rolling of steelmaking. Thus, the aim of this research was to propose the density determination method for the oxide scale. The samples used were prepared by the high-temperature oxidation of iron plate, consisting of 96% Fe_1-xO and 4%Fe₃O₄, and there were voids in the Fe_1-xO layer. The density was determined by four methods based on (1) thickness and mass of oxide scale, (2) the mass balance in the sample, (3) volume balance in the sample, and (4) single crystal density and volume of voids. All of the methods considered the non-stoichiometry of Fe_1-xO because the perfect FeO has a much larger density. The density of the oxide scale was firstly determined by assuming that the oxide scale consisted only of Fe_1-xO. The methods (1) and (2) did not show reasonable density and reproducibility. The results by methods (3) and (4) showed reasonable values with good reproducibility. The density was then determined again by methods (3) and (4), taking into account the presence of Fe₃O₄. It is also discussed the effect of density revision on the thermal diffusivity/conductivity determination of the oxide scale.