Compressive strength and processing of camphene-based freeze cast calcium phosphate scaffolds with aligned pores

Porous calcium phosphate (CaP) scaffolds with aligned pores were fabricated by unidirectionally freezing a CaP/camphene slurry at 32 °C for various times (1, 2, 3 days). During this process, camphene dendrites grew preferentially from the bottom to the top of the cast body. The frozen samples were then freeze-dried to remove the solid camphene and sintered at 1200 °C for 3 h to densify the CaP walls. All of the fabricated samples showed a highly aligned pore structure with a porosity of 62-65 vol.%, regardless of the freezing time. As the freezing time was increased from 1 to 3 days, the pore size increased from 122 to 166 μm due to the continual overgrowth of camphene dendrites, while the compressive strength decreased from 9.3 ± 1.6 to 6.2 ± 1.3 MPa due to the increase in pore size. However, it should be noted that the compressive strength of the sample tested parallel to the freezing direction was much higher than that of the sample tested normal to the direction of freezing, indicating the utility of the aligned pores.