Functionally Gradient Material Ceramics of Hydroxyapatite and Yttria Partially Stabilized Zirconia Prepared by Spark Plasma Sintering for Biocompatibility and Mechanical Strength

Hydroxyapatite, Ca 10 (PO 4 ) 6 (OH) 2 : HA, is biocompatible with human hard tissue. Zirconia has mechanical strength and toughness. Spark plasma sintering (SPS) is a processing technique that makes it possible to prepare materials at low temperatures. Therefore, the objective of this study is to use the SPS method to prepare functionally gradient material (FGM) ceramics with the biocompatibility of HA and the strength of yttria partially stabilized zirconia (Y-PSZ). Fine powders of HA and Y-PSZ (ZrO 2 + 3 mol % Y 2 O 3 ) were poured into the graphite mold and then subjected to SPS at 1100 °C for 10 min. The outer layer has a mixing ratio of 70 wt % HA : 30 wt % Y-PSZ and the other layers are deposited by gradually changing the mixing ratio of HA and Y-PAZ. Each layer in the obtained composite (1.5 mm$\phi$ $\times$ 1.7 mm) was approximately 0.25 mm thick. The measured compressive strength of the composite prepared by SPS at 1100 °C for 10 min was 950 MPa.