Thermochemische Berechnungen und experimentelle Untersuchungen zur Lösungskorrosion feuerfester Baustoffe

Translated title of the contribution: Thermochemical calculations and experimental investigations of the melt corrosion of refractories

Viktoria Reiter

Research output: ThesisDoctoral Thesis

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Abstract

Refractories in metallurgical vessels must resist high temperatures, thermomechanical stresses and the attack of corrosive atmospheres, hot metals and slags (chemical wear). For ceramically bonded materials the melt corrosion proceeds via penetration and dissolution. The present study comprises thermochemical calculations with the software package FactSage to describe the melt corrosion of refractories by slags of the non ferrous metals industry (fayalite, calciumferrite, ferrous-calciumsilicate) and the electric arc furnace. First of all the corrosion environment in the metallurgical vessels has been described and the slags have been characterised with regard to their phase composition and melting behaviour. Afterwards the solubilities of various refractory materials have been determined to evaluate their relative corrosion resistance. The dissolution behaviour has been characterised with regard to potential reaction products formed at the interface refractory/slag, the solubility limits of the refractory components in the slags and the amount of dissolved refractory material in 100 g slag. Both indirect and direct dissolution have been considered in the investigations. Indirect dissolution involves the formation of one or more reaction products adherent to the refractory/slag interface which may act as a protective layer leading to reduced dissolution rates. In the case of direct dissolution no reaction products are formed. Post-mortem investigations of refractories reveal that direct dissolution is decisive in practice. The solubilities are lower in the case of indirect dissolution compared to the direct one. To evaluate the calculated results the dissolution behaviour of magnesia in fayalite slags has been determined experimentally as well as the results of corrosion studies of other authors have been consulted. The calculated results agree well with the results of experimental corrosion studies and thus the thermochemical approach is justified and promising for the characterisation of the melt corrosion of refractories. As shown in this study, the dissolution rate is a function of many variables including characteristics of the slag (e.g. basicity, composition) as well as prevailing process conditions (e.g. temperature, atmosphere). To reduce the wear rate of refractories emphasis must be placed on the one hand on product development and on the other hand on the metallurgical practice with regard to slag chemistry and service conditions.
Translated title of the contributionThermochemical calculations and experimental investigations of the melt corrosion of refractories
Original languageGerman
QualificationDr.mont.
Supervisors/Advisors
  • Harmuth, Harald, Assessor A (internal)
  • Preis, Wolfgang, Assessor B (internal)
Publication statusPublished - 2008

Bibliographical note

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Keywords

  • refractory
  • melt corrosion dissolution
  • thermochemical calculations
  • slags of the non ferrous metals industry
  • fayalite slag
  • calciumferrite slag
  • ferrous-calciumsilicate slag
  • electric arc furnace slag

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