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arXiv · 2110.11632

Thermal conductivity of oxide scale and its components in the range from 0 C to 1300 C: Generalized estimates with account for movability of phase transitions

Emmanuil Beygelzimer·Yan Beygelzimer
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Abstract

The data of different authors on the thermal conductivity of wustite Fe1-xO, magnetite F3O4, hematite Fe2O3 and pure iron are systematized. The generalized values are described by piecewise smooth functions containing as varying parameters the temperatures of magnetiv and polymorphic (for iron) transformations as well as the thermodynamic stability boundary (for wustite). At polymorphic transformation a finite break of the thermal conductivity function is envisaged, at othet critical points only a break of its temperature derivative is acceptable. The proposed formulas are presented in two forms: the general form that allow varying the values of critical temperatures and the particular form corresponding to their basic values: the boundary of thermodynamic stability of wustite - 570 C, the Curie points of magnetite - 575 C, hematite - 677 C, iron - 770 C and polymorphic transformation temperature of iron - 912 C. To calculate the thermal conductivity of oxide scale as a whole, it is proposed to take into account separately metallic iron and composite matrix of iron oxides. Model computations using the proposed formulas shows that the true thermal conductivity of oxide scale (without pores), depending on the temperature may be from 3 to 6 W / (m K) in the absence of metallic iron and up to 15 W / (m K) if free iron is released in the eutectoid decay of wustite. The effective thermal conductivity of oxide scale, taking into account its real porosity, may be lower by 15-35%. The obtained dependencies are recommended for use in mathematical simulation of production and processing of steel products in the presence of oxide scale on their surface.

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Emmanuil Beygelzimer, Yan Beygelzimer. 2021-10-22. Thermal conductivity of oxide scale and its components in the range from 0 C to 1300 C: Generalized estimates with account for movability of phase transitions. https://arxiv.org/abs/2110.11632

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