Chem. J. Chinese Universities ›› 2026, Vol. 47 ›› Issue (6): 20250216.doi: 10.7503/cjcu20250216

• Articles: Inorganic Chemistry • Previous Articles     Next Articles

Preparation and Hydration Resistance of Carbon Nanotubes-CaCO3 co-Coated Superhydrophobic MgO-CaO Grains

WANG Xin1,2, ZHANG Ling1, ZHANG Haijun1(), WANG Junkai2   

  1. 1.State Key Laboratory of Advance Refractories,Wuhan University of Science and Technology,Wuhan 430081,China
    2.School of Materials Science and Engineering,Henan Polytechnic University,Jiaozuo 454003,China
  • Received:2025-08-01 Online:2026-06-10 Published:2025-09-18
  • Contact: ZHANG Haijun E-mail:zhanghaijun@wust.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(U23A20559)

Abstract:

Magnesia-calcia(MgO-CaO) refractories are widely used in tundish linings and continuous casting furnaces owing to their high melting point, thermal stability, resistance to slag corrosion, and effectiveness in purifying molten steel. However, their susceptibility to hydration in humid environments severely limits their practical applications. To enhance the hydration resistance of MgO-CaO materials, this study presents a novel one-step catalytic chemical vapor deposition method using soybean oil as a carbon source and cobalt(Co) as a catalyst to synthesize carbon nanotubes(CNTs) and calcium carbonate(CaCO3) co-coated superhydrophobic MgO-CaO grains. The effects of pyrolysis temperature, holding time and catalyst loading on the microstructure and hydration resistance of the modified MgO-CaO grains were systematically investigated. The results indicate that the optimal synthesis conditions for the CNTs-CaCO3 co-coated superhydrophobic MgO-CaO grains are as follows: reaction temperature of 700 ℃, 2.0%(mass ratio of the supported catalyst to MgO-CaO grains) Co catalyst loading, and holding time of 1 h. Under these conditions, the modified aggregates exhibited a water contact angle of 155°, and a minimal hydration-induced weight gain of only 0.73%(mass fraction) after exposure at 70 ℃ and 85% relative humidity for 24 h, the hydration resistance has been improved by 9.47 times compared to unmodified MgO-CaO grains, and 2.01 times to CaCO3 coated MgO-CaO grains. The synergistic protective effects of the hydrophobic CNT layer and the CaCO3 shell effectively hindered moisture ingress and subsequent hydration reactions. This study provides an facile and efficient approach for enhancing the hydration resistance of MgO-CaO refractories.

Key words: MgO-CaO grain, Hydration resistance, Carbon nanotubes-CaCO3 co-coating, Cobalt catalyst

CLC Number: 

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