Fabrication of Novel BPO4 Ceramic Foams Using the Combination of the Direct Foaming Method and Freeze‐drying Techniques

In this study, ammonium phosphate monobasic and boric acid were used as the primary starting materials to produce BPO4 powder by solid-state reaction. Using BPO4 powders as the main raw material, BPO4 ceramic foams were prepared for the first time using the direct foaming method and freeze-drying techniques. The effects of the additive content and solid loading on the slurry's rheological behavior were investigated, and the microstructures and properties of the as-prepared BPO4 ceramic foams were examined. The results reveal that the porosity of the BPO4 ceramic foams synthesized at 1223 K ranged from 84.2% to 90.4%, the compressive strength ranged from .12 MPa to .72 MPa, and the thermal conductivity ranged from .32 W/(m center dot K) to .74 W/(m center dot K) (298 K). The findings of this study have great significance for the development of new thermal insulation ceramic materials.