Impact of cyclic CIP on the oxidation resistance and physical properties of a newly developed boron-free self-glazing Al2O3-C refractory

The impact of cyclic cold isostatic pressing (C-CIP) on the oxidation resistance and physical properties of a boron-free self-glazing Al2O3-C refractory for steel casting applications was investigated. Pulsations with amplitudes of 20, 40 and 65 MPa were thereby applied either at maximum isostatic pressure or at increasing pressure. The maximum isostatic pressures applied were 80, 100 and 150 MPa, respectively. Both cycling pressurizations improved the oxidation resistance and physical properties. Higher densities were obtained at higher cycling amplitudes, in particular when the pulsations were applied at maximum isostatic pressure. In addition, the evolution of a broader pore size distribution with peaks at pores larger than 4 μm was found. The pore size distributions of the samples pressed by C-CIP at increasing pressure were narrower, with higher peaks at smaller pore sizes in the area of 2.5 μm. It was shown that utilizing cycling pressurization enables tailoring of pore sizes in carbon-bonded refractories as well, providing a powerful tool for the material design of refractories.