Štúdium opotrebovania nísteje narážacej pece okovinami

Abstract

Using the knowledge from theoretical area, there were physical – mechanical tests and corrosion tests carried out on four grades of refractory materials. Three castables: Calde Cast LT 90 SP G8 (marked as P), Kofond FTSP 25 (marked as F), Hydra-Plus Spinel C-2 (marked as H), and one fusion cast corundum Alodur Surfacast SG 1 (marked as K). Corroding medium was the steel type Trafo and Kohal, the two steels most frequently heated in USS Košice Reheat Furnaces. Within the frame of physical tests, Thermal Cycling on Refractories was carried out and thermal expansion was determined on the tested refractory materials. The test has shown that the material with best resistance to temperature shocks was Hydra-Plus Spinel C-2 material, which didnt have any corpuscle deteriorated, the corpuscles had only small cracks. The materials with best resistance to melt corrosion were molden corundum Alodur Surfacast SG 1 and Calde Cast LT 90 SP G8 castable. These refractory materials have very low contents of iron oxides, which can be observed by chemical point microanalysis. The third part of experiments was corrosion evaluation of refractory materials using microscopic analysis. Minerals, spinel and hibonite were identified in all castables. Analysis of refractory material samples, using scanning electron microscope, shows layer cross-section of refractory material – interface – scales. This analysis showed distribution of individual elements on microstructure of refractory material – interface – scales. Aluminum oxides, with presence of calcium, magnesium, iron and silicon was confirmed. The fourth part of dissertation thesis deals with thermodynamic analysis; it analyzes generation of possible phases in contact between slab (steel) and Reheat Furnace hearth (refractory material).