Superhydrophobic CNTs/CaCO3-coated MgO-CaO powder for enhancing hydration resistance and high-temperature performance of ultralow-carbon MgO-CaO-C refractories

Low-carbon MgO-CaO-C refractories are promising for clean steel refining, but their application is limited by CaO hydration and the deterioration of high-temperature performance caused by reduced carbon content. In this work, a CNTs/CaCO 3 co-coated MgO-CaO powder (CC-MCP) was successfully fabricated via a densified micro-zone deposition process employing MgO-CaO particles, polyethylene powder, and starch as materials. The as-prepared CC-MCP were incorporated into low-carbon MgO-CaO-C refractories to achieve a “two birds with one stone” effect, simultaneously enhancing both hydration resistance and high-temperature service performance. Compared to the control sample prepared with flake graphite as carbon source, the counterpart containing CC-MCP exhibited superior hydration resistance and high-temperature performances, including a 286% improvement in water vapor resistance, an increase of up to 209% in oxidation resistance, a 36% improvement in thermal shock resistance, and a reduction in slag penetration depth from 654 μm to 435 μm. This “two birds with one stone” strategy provides an effective and scalable route for developing high-performance ultralow -carbon MgO-CaO-C refractories for clean steel production, while simultaneously offering a practical solution to the hydration challenges faced by CaO-containing refractories under harsh storage and service conditions.