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Using poly-methyl methacrylate as a pore-forming agent, porous β-tricalcium phosphate (β-TCP)/t-ZrO2 composites were fabricated depending on the volume percentages (vol.%) of t-ZrO2 powder. In the porous sintered bodies, hybrid pores, about 20 and 200 μm in diameter, were homogenously dispersed in the β-TCP/t-ZrO2 matrix and showed good interconnection. On the other hand, β-TCP-(t-ZrO2)/polycaprolactone (PCL) composites were fabricated by the melt infiltration process using porous β-TCP/t-ZrO2 bodies. The relative density of the β-TCP-(t-ZrO2)/PCL composites increased as the vol.% of t-ZrO2 increased and its maximum value was about 98.6%. However, the hardness, bending strength and elastic modulus of β-TCP-(t-ZrO2)/PCL composites decreased due to the low densification of porous β-TCP/t-ZrO2 bodies as the volume percentages of t-ZrO2 content increased. The values (using 20 vol.% of t-ZrO2) were 11.4 Hv, 25.5 MPa and 17.2 GPa, respectively.

Porous Al₂O₃-(m-ZrO₂) composites were fabricated by pressureless sintering, using different volume percentages (40%-60%) of poly methyl methacrylate (PMMA) powders as a pore-forming agent. The pore-forming agent was successfully removed, and the pore size and shape were well-controlled during the burn-out and sintering processes. The average pore size in the porous Al₂O₃-(m-ZrO₂) bodies was about 200 ㎛ in diameter. The values of relative density, bending strength, hardness, and elastic modulus decreased as the PMMA content increased; i.e., in the porous body (sintered at 1500℃) using 55 vol % PMMA, their values were about 50.8%, 29.8 ㎫, 266.4 Hv, and 6.4 ㎬, respectively. To make the Al₂O₃-(m-ZrO₂)/polymer hybrid composites, a bioactive polymer, such as PMMA, was infiltrated into the porous Al₂O₃-(m-ZrO₂) composites. After infiltration, most of the pores in the porous Al₂O₃-(m-ZrO₂) composites, which were made using 60 vol % PMMA additions, were infiltrated with PMMA, and their values of relative density, bending strength, hardness, and elastic modulus remarkably increased.

Synthesis and characterization of material properties of biphasic calcium phosphates (BCP)/polycaprolactone (PCL) composites, which were obtained by melt infiltration of PCL using porous BCP bodies, were investigated. Using 70 vol.% of poly methyl methacrylate (PMMA) powder as a pore-forming agent, porous BCP bodies were obtained by pressure less sintering depending on the temperature. The porous bodies obtained showed interconnected, spherical pores about 200 microm in diameter. Densification of the pore frame improved and grain growth increased remarkably as the sintering temperature increased. Molten PCL was infiltrated into porous BCP bodies to obtain the BCP/PCL composites. The material properties such as the relative density, hardness, bending strength, and elastic modulus of BCP/PCL composite, which was sintered at 1200 degrees C, were 95.7%, 11.2 Hv, 31.6 MPa and 10.2 GPa, respectively.