Kinetics and Mechanism of Oxidation Induced Contraction of MgAl2O4 Spinel Carbon Composites Reinforced by Al4C3in situ Reaction

Kinetics and mechanism of oxidation induced contraction of MgAl2O4 spinel carbon composites reinforced by Al4C3in situ reaction were researched in air using vertical high temperature thermal dilatometer from 25 °C to 1 400 °C. It is shown that oxidation induced contraction of MgAl2O4 spinel carbon composites reinforced Al4C3in situ reaction is the common logarithm of oxidation time t and the oxygen partial pressure P inside MgAl2O4 spinel carbon composites reinforced by Al4C3in situ reaction in air at 1 400 °C is as follows: P=F(−2.75×10−4A+2.13×10−3) lnt. The nonsteady diffusion kinetic equation of O2 at 1 400 °C inside the composites is as follows: J=De lnt. Acceleration of the total diffusional flux of oxygen inside the composites at 1 400 °C is in inverse proportion to the oxidation time. The nonsteady state effective diffusion coefficient De of O2(g) inside the composites decreases in direct proportional to the increase of the amount of metallic aluminium. The method of preventing the oxidation induced contraction of MgAl2O4 spinel carbon composites reinforced by Al4C3in situ reaction is to increase the amount of Al. The slag erosion index of MgO-Al2O3 spinel carbon composite reinforced by Al4C3in situ reaction is 0.47 times that of MgO-CaO brick used in the lining above slag line area of a VOD stainless steel-making vessel. HMOR of MgO-Al2O3 spinel carbon composite reinforced by Al4C3in situ reaction is 26.7 MPa, HMOR of the composite is 3.6 times the same as that of MgO-CaO brick used in the lining above slag line area of a VOD vessel. Its service life is two times as many as that of MgO-CaO brick.