Abstract

Alumina – Magnesia - Graphite (AMC) bricks are used in the metal zone of steel ladles in Ternium Siderar steelmaking. These bricks are based on different types of alumina aggregate, carbon in graphite form and have magnesia as an additive. When heated, the spinel is formed to ensure sufficient residual thermal expansion. This behavior closes the joints between the bricks and the slag penetration is reduced.

The wear mechanism of the lining refractory bricks for steel ladle metal line corresponds to a combination of different chemical (carbon oxidation, steel and slag attack), thermal (heating and cooling cycles) and mechanical stresses. In the current work, a post mortem study of different suppliers AMC bricks was performed through optical and electronic microscopy (SEM) and EDS analysis. By using these techniques the refractory microstructural changes were evaluated.

Also, five different grades of AMC bricks are comparatively characterized and their degree of spinel formation in –situ are determined as a temperature function. Immersion tests or "dipping test” were done in air atmosphere at 1600° C for 1 hour using steel and ladle slag. Corrosion mechanisms were analyzed.

As a result, the correlation between the laboratory test and the post mortem study defined the most important parameters to select AMC bricks for steel ladles.