Two main experiments were conducted for this study: Hot stage microscopy −Mixture: raw material : slag = 1:1 weight ratio −Shape: small cube of 3 mm side −Heating: 10°C/min up to 1500°C −Computer treatment: measure of height of sample Heat treatment of pellets −Mixture: raw material : slag = 3:1 weight ratio −Pellets: Ø20 mm, pressed at 80 MPa −Heat treatment: 5°C/min, dwell 1h at 1400°C −Observation by SEM with EDS ESR Position 04 CHARACTERISTIC TEMPERATURE DETERMINATION OF REFRACTORY RAW MATERIALS AND SLAG MIXTURES Camille REYNAERT Early Stage Researcher mail: reynaert@agh.edu.pl Advanced THermomechanical multiscale mOdelling of Refractory Linings Supervisors & University Consortium of 15 European Partners Edyta ŚNIEŻEK Authors: Camille REYNAERT, Edyta ŚNIEŻEK, Jacek SZCZERBA Address: AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Krakow, Poland Materials: Introduction: Conclusions: Steel industry is the most important consumer of refractory bricks. Refractories are commonly used as the linings of steel equipment because they can sustain very high temperature and corrosive attacks in the working environment. However due to the harsh working condition, their life span is limited. Corrosion mainly by slag is the principal phenomenon responsible for the degradation and wear of the bricks. Acknowledgments This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement no.764987 The materials used are typical powders that can be found in refractories for steel making applications and slags pick up from a steel ladle. The powder is calcium zirconate with composition given in table 1. The slags are silica rich slags. They were taken at different moment of the treatment of a batch of steel in the ladle. They composition is given in table 2 and they equilibria in a phase diagram in the figure 2. Table 2: Composition of the slags obtained by XRF. Table 1: Composition of the powder obtained by XRD. Figure 2: Curves obtain by hot stage microscopy for calcium zirconate. Jacek SZCZERBA Calcium zirconate corroded by different slags exhibit different behaviors. This is particularly noticeable between the first mixture (CaZrO3 + SiS1) and the others. This is due the major difference in composition between SiS1 and the others slags (SiS2/3/4). When using phase equilibria diagram, one can notice that SiS1 is in another equilibria zone compare to SiS2/3/4 (figure 1). MgO SiO2 SiS2/3/4 SiS1 Results: Expansion Shrinkage Initial softening Flowing CaZrO3 Start End Start End + SIS1 100 1080 1080 1380 1400 1460 + SiS2 100 960 960 1410 1410 / + SiS3 100 920 1080 1400 1420 / + SiS4 100 940 940 1400 1400 / • For SiS1, the matrix melted and grains were partly dissolved as they appear rounded. • For SiS2/3/4, only part of the slag melted but grains were not attacked: almost no rounded grains. The different characteristics temperatures for each mixture are given in table 3. The observed differences can be explained by the formation of different phases in the mixture and differences in microstructure as is observed in Fig 3a and b. CaZrO3 + SiS1 CaZrO3 + SiS2 CaZrO3 + SiS3 CaZrO3 + SiS4 Calcim zirconate - CaZrO3 Zirconium oxide - ZrO2 Spinel - Mg8Al16O32 Mn3O4 Gehlenite - Ca4Al4Si2O14 Braunite - Mn56Si8O96 Grossular - Ca24Al16Si24O96 Calcim zirconate - CaZrO3 Zirconium oxide - ZrO2 Periclase - MgO β-Ca2SiO4 – Monoclinic Oldhamite - CaS Ca16Si8F8O28 Calcim zirconate - CaZrO3 Zirconium oxide - ZrO2 Periclase - MgO β-Ca2SiO4 – Monoclinic Oldhamite - CaS Ca16Si8F8O28 Calcim zirconate - CaZrO3 Zirconium oxide - ZrO2 Periclase - MgO β-Ca2SiO4 – Monoclinic Oldhamite - CaS Ca16Si8F8O28 Pyroxene ideal - MgSiO3 The phase compositions help to understand the phenomena that took places. For the first mixtures, gehlenite melts around 1250°C which explains the sudden drop in volume which in then sustain by the dissolution of zirconate grain in the slag as can be observed