Highly porous biphasic calcium phosphate (BCP) ceramics with large interconnected pores by freezing vigorously foamed BCP suspensions under reduced pressure

This article proposes a new way of producing highly porous biphasic calcium phosphate (BCP) ceramics with large interconnected pores by freezing a vigorously foamed BCP suspension under reduced pressure, which allows the air bubbles incorporated into the BCP suspension to expand extensively. All the fabricated samples produced with various degrees of expansion of the BCP suspension (0, 150, 200, and 250 vol%) showed a highly uniform porous structure with their unique microporous BCP walls. The sizes of the pores and interconnections between the pores increased remarkably from 74 ± 21 μm to 295 ± 93 μm and 22 ± 8 μm to 123 ± 60 μm, respectively, with increasing degree of expansion from 0 to 250 vol%. However, the compressive strength decreased from 1.2 ± 0.29 MPa to 0.4 ± 0.07 MPa with increasing degree of expansion from 150 to 250 vol%.