Abstract
The corrosion resistance of spinel containing cement bonded castables has been extensively investigated in the past. However, corrosion of no-cement refractory castables (NCC) has not been widely studied since the use of NCC has been relatively limited up till now. This paper focuses on the slag resistance of NCCs, and the often-used spinel containing low cement castable (LCC) is used as the reference. Three different NCC binders were designed: (i) Al2O3 + MgO (alumina bond), in situ spinel formation; (ii) Al2O3 + SiO2 (microsilica-gel bond), mullite formation; and (iii) Al2O3 + MgO + SiO2 (MgO-SiO2 bond). Slag resistance tests were conducted using the static crucible method with ladle slag. The corrosion mechanisms were studied by means of Scanning Electron Microscopy (SEM/EDS), X-ray Diffraction (XRD), and thermodynamic simulations. The results confirmed that the mineral phases, microstructure, and liquid formation at a high temperature of the refractory materials had a strong impact on the corrosion resistance. The slag resistance was significantly improved when the cement was replaced by the cement-free binders.
Highlights
Due to the excellent corrosion resistance to basic slags and good thermo-mechanical properties, either in situ forming or pre-formed spinel (MgAl2 O4 ) containing cement bonded refractory castables (low cement castables (LCCs)) have been widely used for steel ladles [1]
Many publications have highlighted that the in-situ spinel forming LCCs exhibit better slag resistance compared to the pre-formed spinel containing LCCs due to the fine and well distributed spinel grains derived from the reaction between MgO and Al2 O3 during sintering
The objective of this paper is to examine and understand the corrosion mechanism of alternative no-cement refractory castables (NCC) binders
Summary
Due to the excellent corrosion resistance to basic slags and good thermo-mechanical properties, either in situ forming or pre-formed spinel (MgAl2 O4 ) containing cement bonded refractory castables (low cement castables (LCCs)) have been widely used for steel ladles [1]. The expansive behavior is commonly caused by: (i) MgO hydration during curing and dry-out stage and (ii) in situ spinel formation and formation of calcium hex-aluminate (CA6 ) at high temperatures. To overcome these problems, small amounts of microsilica are often added, e.g., 0.5–1.0%. Of the tested NCC binders, the two component binders, alumina bond and microsilica-gel bond, showed better corrosion resistance than the triple mix binder, MgO-SiO2 bond
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