Comprehensive dissolution studies and accurate quantification of the dissolution parameters are required to design improved refractory materials with enhanced lifetime for cost and resource effectiveness. As the rotating finger-test (RFT) is a widely used tool according to state of the art for wear quantification, a contemporary RFT device with in-situ wear profile measurement by high-resolution laser was used in this study for accurate wear measurements. In general, dissolution is a diffusion-controlled process in liquid medium. Hence, the diffusivity of the dissolving component is the point of interest to quantify dissolution. Mass transfer equations could be applied to determine diffusivity. A number of mass transfer equations are reported in the literature, but most of them are not directly applicable for the typical RFT with bottom clearance. After suitable modifications, few of them may show satisfactory results. A simulation method and a Sherwood relation based on the simulation results for the typical RFT experiments are the most promising approaches for effective binary diffusivity determination. These two methods consider the actual sample geometry and flow around it, whereas samples are perfect cylinder in all other cases. Furthermore, consideration of advection in the orthogonal direction to the solid/melt interface and the effect of Stefan’s velocity on the boundary layer thickness have to be considered for accurate results. To exemplify these methods, dissolution of alumina fine ceramics in a CaO–Al2O3–SiO2 slag with a CaO/SiO2 weight ratio 0.93 was studied at 1450, 1500, and 1550 °C with 200 rpm. At each experimental temperature eight corrosion steps were carried out. The dissolution times per corrosion step at 1450 °C, 1500 °C, and 1550 °C were set to 150, 90, and 60 minutes, respectively. Dissolution parameters (i.e. corroded volume, surface area, mean radius, tip radius and immersion length) were calculated from the laser measurements to determine mass flux densities. Subsequently, effective binary diffusivities of alumina for all corrosion steps have been derived from total mass flux densities using a method based on Sherwood relations. Diffusivity of one corrosion step at each experimental temperature has been compared with results obtained from other methods. Arrhenius plot of the diffusivities was checked as a test for plausibility.
|Veröffentlicht - 4 Juli 2023
|XVIIIth Conference of the European Ceramic Society - Lyon, Frankreich
Dauer: 2 Juli 2023 → 6 Juli 2023
|XVIIIth Conference of the European Ceramic Society
|2/07/23 → 6/07/23