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

• Published in: Journal of Wuhan University of Technology. Materials science edition 2020, Vol.35 (4), p.778-785
• Main Authors: Yang, Mengyao, Xiao, Guoqing, Yang, Ding’ao, Yuan, Shouqian, Zhao, Jizeng, Zhao, Wei, Gao, Song
• Format: Article
• Language: English
• Subjects: Acceleration; Aluminum oxide; Calcium oxide; Carbon; Cementitious Materials; Chemistry and Materials Science; Composite materials; Diffusion coefficient; Extensometers; High temperature; Kinetic equations; Magnesium oxide; Materials Science; Oxidation; Partial pressure; Reaction kinetics; Service life; Slag; Spinel; Stainless steels; Steel making; Vessels
• ISSN: 1000-2413; 1993-0437
• DOI: 10.1007/s11595-020-2320-7

Kinetics and mechanism of oxidation induced contraction of MgAl 2 O 4 spinel carbon composites reinforced by Al 4 C 3 in 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 MgAl 2 O 4 spinel carbon composites reinforced Al 4 C 3 in situ reaction is the common logarithm of oxidation time t and the oxygen partial pressure P inside MgAl 2 O 4 spinel carbon composites reinforced by Al 4 C 3 in situ reaction in air at 1 400 °C is as follows: P=F (−2.75×10 −4 A +2.13×10 −3 ) ln t . The nonsteady diffusion kinetic equation of O 2 at 1 400 °C inside the composites is as follows: J=D e ln t . 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 D e of O 2 (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 MgAl 2 O 4 spinel carbon composites reinforced by Al 4 C 3 in situ reaction is to increase the amount of Al. The slag erosion index of MgO-Al 2 O 3 spinel carbon composite reinforced by Al 4 C 3 in 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-Al 2 O 3 spinel carbon composite reinforced by Al 4 C 3 in 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.