Effect of the chemical composition of slag on the corrosion of calcium zirconate material

• Published in: Materials chemistry and physics Vol. 258; p. 123844
• Main Authors: Ludwig, Maciej, Wiśniewska, Klaudia, Śnieżek, Edyta, Jastrzębska, Ilona, Prorok, Ryszard, Szczerba, Jacek
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15-01-2021; Elsevier BV
• Subjects: Aluminum; Basicity; Bulk density; Calcium aluminate; Calcium carbonate; Calcium ions; Calcium zirconate; Chemical composition; Composition effects; Corrosion; Corrosion effects; Corrosion tests; Dicalcium silicate; Diffusion layers; Disintegration; Gehlenite; Hot stage microscopy; Liquid phases; Microscopy; Pellet test; Phase composition; Porosity; Reaction time; Silicon; Slag; Synthesis; XRD; Zirconium dioxide; Slag; Pellet test; XRD; Corrosion; Calcium zirconate
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2020.123844

Corrosion of calcium zirconate material, synthesized from CaCO3 and ZrO2 powders, with slags of different basicity was investigated at 1400 °C for 5 h and 10 h of soaking time. Slags were synthesized from high purity powders. Two corrosion tests were applied – hot stage microscopy and pellet test. The phase composition of the as-synthesized and after-corrosion samples was determined by X-Ray Diffraction technique. The Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy was applied to investigate the microstructures of the corroded samples. Moreover, bulk and helium density, open porosity, and firing shrinkage were determined. The conducted research revealed that interaction of CaZrO3 with high basicity slag (2.00B) resulted in the total disintegration of the samples in consequence of γ-Ca2SiO4 formation. The slags of lower basicity (1.00B and 1.50B) induced the formation of the aggressive liquid phase which dissolved a significant amount of Zr4+. During the reaction with the most acidic slags (0.25B and 0.50B) diffusion of Ca2+ from calcium zirconate into the surrounding liquid phase was accompanied by the reversed diffusion of Si4+, and a formation of protective layers composed of new phases of gehlenite (Ca2Al[(Si,Al)2O7]) baghdadite Ca3Zr[O2|Si2O7], C3ZS2) and calcium aluminates (CaAl2O4 and CaAl4O7) was observed. The extended reaction time revealed ‘no significant impact on the reaction of CaZrO3 with 0.25B slag, while time-extended progressive corrosion was observed for slags 1.00B and 1.50B. The order of the improved resistance of CaZrO3 against the slag of different basicity was as follows: 2.00B < 1.50B < 1.00B < 0.50B and 0.25B.
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•CaZrO3 was prepared using CaCO3 and ZrO2 powders in two-stage heat treatment.•Slags of different basicities (0.25, 0.50, 1.00, 1.50 and 2.00) were applied in corrosion tests.•Slags 0.25 and 0.50 induced the diffusion of Ca2+ from CaZrO3 to the surrounding slag.•The aggressive liquid phase was formed in 1.00 and 1.50 slag, and γ-Ca2SiO4 in slag 2.00•Extended reaction time showed the increased dissolution of Zr4+ in 1.00 and 1.50 slags.