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The Effect Of Oxidation Resistance By Addition Of Calcium Hexaboride

2018-11-8      View:

In order to improve the oxidation resistance of carbon-containing refractories, some additives are often added, and appropriate antioxidant additives are selected according to different types of carbon-containing refractory substrates. For example, Mg and Al are often added to the MgO-C refractory, and SiC is often added to the Al2O3 - C refractory.


Calcium hexaboride is considered to be a good refractory antioxidant additive, especially suitable for MgO-CaO-C refractories. Although many studies have been carried out by the predecessors, the kinetics and thermodynamic behavior of calcium hexaboride to inhibit the oxidation of carbon, as well as the reaction mechanism, have yet to be further elucidated.


The appearance of the glass phase contributes to the formation of a dense oxide layer, effectively preventing the diffusion of oxygen in the environment into the interior of the refractory material, thereby improving the oxidation resistance of the refractory material.


The formation of a dense oxide layer prevents oxidation of carbon in the refractory material, and temperature is an important factor in the formation of the oxide layer. When heated to 150 °C, it was observed that there was an oxide layer between the oxidized and unoxidized regions, and its composition was mainly calcium-containing borate.


When the oxidation resistance of the MgO-CaO-C refractory is improved by adding calcium hexaboride as an antioxidant, the reasonable addition amount should not exceed 4%.