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In this paper structural, electrical, electrochemical and thermal (DSC) characterization of series of manganese spinel samples with manganese substituted to different degree (x = 0 – 0.5) with nickel are presented. The conductivity and thermoelectric power measurements were performed in wide temperature range also versus oxygen partial pressure and for deintercalated samples. Electrochemical studies of these cathode materials were conducted in Li / Li+ / LiyNixMn2−xO4 type cells. Substitution of manganese with nickel causes disappearance of the phase transition characteristic of LiMn2O4 spinel. Studies of electrical properties reveal that Ni ions do not participate in charge transport at low temperatures. In the charge curves of Li / Li+/ LiyNixMn2−xO4 cells there are two visible plateaux, separated with distinct potential jump (~0.5V), which position on Li content perfectly matches the Mn3+ content in the doped cathode material. The lower plateau is related to the Mn3+ → Mn4+ oxidation, while the next of higher voltage, of the dopant Ni2+ → Ni4+ oxidation. The schematic diagrams of relative Mn – Ni electronic levels alignment are proposed.

Slide gates are used to control the flow rate of molten steel in continuous casting. The properties that are important for materials for slide gate application are corrosion resistance, thermal shock resistance, abrasion resistance, and strength. However, operating conditions and in particular steel chemistries vary by shop and require development of different refractory material qualities. Alumina-carbon refractories are the prevalent family for slide gate application due to their superior thermo-mechanical properties. However, they suffer from extensive corrosion in aggressive applications. On the other hand, magnesia based refractories show promising corrosion resistance, but they are poor in terms of thermal shock and abrasion resistance. A novel approach using material based solution was employed to utilize a combination of properties of both refractory material families. This approach resulted in a material composite that jointly exhibits the thermomechanical properties and abrasion resistance of alumina based refractory and the corrosion resistance of magnesia based refractory. This paper will present the properties, key limiting factors, and results of usage at three steel plants.