Effect of Mg/Al ratios on hydration mechanism of tabular alumina carbon composites reinforced by Al₄C₃ in situ reaction

Abstract

Hydration mechanism of tabular alumina carbon composites reinforced by Al₄C₃ in situ reaction with Mg and Al was researched in water steam using super automatic thermostatic water bath from 25 °C to 85 °C. It is shown that hydration mechanism of the composites is chemical reaction control at 44.3 °C-84 °C in H₂O(g). The hydration was controlled by diffusion from 24.7 °C to 33 °C. The ratio of added Mg/Al influences the HMOR of the composites.The mechanism of HMOR of the composites with different ratios of Mg/Al can be discovered by means of SEM analysis. The active Mg/Al powder and flake graphite inside give the composites outstanding hot strength resulting from the interlocking structure of Al₄C₃ crystals at high temperature. Besides, the matrix changes into the Al₄C₃ with high refractoriness. The method of preventing the hydration of tabular alumina carbon composites reinforced by Al₄C₃ in situ reaction was immersed in the wax at suitable temperature or storing them below 33 °C in a dry place or storing them with paraffin-coating.

Keywords

hydration mechanism / tabular alumina / carbon / Al₄C₃ / Mg/Al ratios

References

[1] Lee WE, Robert EM. Evolution of in-situ Refractories in the 20th Century[J]. J. Am. Ceram. Soc., 1998, 81(6): 1385-1410.

[2] Sadrnezhaad SK, Nemati ZA, Mahshid S, et al. Effect of Al antioxidanton the rate of oxidation of carbon in MgO-C refractory bricks[J]. J. Am. Ceram. Soc., 2007, 90(2): 509-515.

[3] Xiangchong Zh.ong. A New Generation of High Performance Refractory Ceramics[J]. Naihuo Cailiao, 2003, 1: 1-10.

[4] Yang D., Yuan S., Jiang M., et al. Anisotropy of Expansion Coefficient and Slag Resistance of Spinel Carbon Bricks[J]. J. Wuhan Univ. Technol. -Mater. Sci. Ed., 2006, 21(6): 142-145.

[5] YANG D.-a, YUAN S., JIANG M., et al. Effects of Aluminium Powder Additions on Properties of Corundum Composite[J]. Naihuo Cailiao, 2006, 40(6): 457-459.

[6] YANG D.-a, YUAN S., JIANG M., et al. Effect of Matrix Composition on Physical Properties of Al₃CON in situ Reaction Reinforced Corundum Composite[J]. J. Wuhan Univ. Technol. -Mater. Sci. Ed., 2008, 23(6): 927-931.

[7] Ding’ao Y.A.N.G.. Effect of Addition of Al and Mg on Properties of Periclase-Spinel-Carbon Brick[J]. China’S Refractories, 2000, 2: 23-28.

[8] Ding’ao Y.A.N.G., Zhiming Y.U., Liuwu F.A.N.. Al4C3 Hydration Thermochemical Analysis for Burned Carbon-containing Refractories with Al[J]. China’s Refractories, 2003, 1: 19-22.

[9] Tanezo I., Tatsuo M., Makoto G., et al. Slaking of Magnesia-Carbon Brick After Heat Treatment[J]. Taikabutsu, 1985, 6: 40-44.

[10] Watanabe A., Takahashi H., Nonobe K., et al. Test Results of Refractory Bricks for Pig Hot Metal Pretreatment Vessel[J]. Taikabutsu Overseas, 1986, 1: 22-25.

[11] Gu G., Jiang Mi.ngxue. The Process Research for the High Quality Slide Nozzle[J]. Heavy Machine Science and Technology, 2003, 2: 13-19.