Properties and behavior of periclase-carbon systems during the firing-process under oxidizing conditions

Conclusions

It is not advisable to introduce more than 20% graphite into the composition of the periclase-carbon refractories because, in this case, the strength of the products decreases significantly and their porosity increases.

The temperature corresponding to the beginning of carbon depletion (burn off) does not depend on its content in the body and amounts to 550–560°C.

Caustic periclase introduced for achieving additional low-temperature densification of the strucutre with reduced degree of carbon depletion did not give the expected effect: the temperature at which carbon depletion begins does not depend on its content in the body.

When fired under oxidizing conditions, a reducing atmosphere is created within the periclase-carbon products which actively reacts with periclase; at and above 1650°C, one observes reduction of MgO up to Mg vapor with its subsequent oxidation and redeposition in the form of a dense layer of secondary MgO; a relict polygonized grain structure of MgO forms in the products and is accompanied by the development of a layered texture exhibiting cyclic recurrence.