Abstract: To address the environmental issues caused by the accumulation of blast furnace slag,this study systematically investigated the effects of alumina silica ratio,Na2 O content,and CaO content on the phase evolution,microstructure,and prop erties of blast furnace slag-based foam ceramics using Pansteel blast furnace slag as the main raw material.The regulation mechanisms of each component on the ceramic properties were analyzed through X-ray diffraction (XRD),scanning electron microscopy (SEM),combined with mechanical property,porosity,and thermal conductivity tests.The results show that increas ing the alumina silica ratio drives the phase transformation from quartz and sphene to alumina and perovskite,significantly en hancing the density,strength,and thermal conductivity of the material.When the Na2 O content reaches 1.75%,the ceramic ex hibits a uniform pore structure,while excessive Na2 O leads to the formation of albite (NaAlSi3 O8 ).Although CaO promotes sintering,excessively high CaO content inhibits the crystallization of anorthite,resulting in deteriorated properties.Under the optimized formulation (mass ratio of blast furnace slag and boric acid of 50∶10,alumina silica ratio of 0.5,Na2 O content of 1.75%),the prepared foam insulation ceramic achieves a flexural strength of 4 MPa,thermal conductivity of 0. 079 5 W/(m·K),bulk density of 2.22 g/cm3,and water absorption of 3.7%,all of which meet the requirements of the standard "Foam Ceramic Insulation Panel for Building" (JG/T 511—2017).

Key words: blast furnace slag,foam ceramics,alumina silica ratio,thermal conductivity